The mass may be smaller and the velocity may be slower than desired, but the rock is rolling in the right direction.

Momentum is sometimes hard to define. In sports, it may be a crucial play that changes the outcome of the game. In business, however, it might be something as simple as a sale that leads to an unexpected customer base. Often, it may seem like a small pebble, but once it starts rolling downhill— gaining mass and velocity along the way — its impact can be significant.

Movement alone, however, is not enough. Just look at the results of our forecast studies during the last eight years, and it’s clear that not all momentum is good momentum. For example, consider the industry’s historical response to business conditions. When answering our first forecast in 2004, 84.5 percent of respondents indicated positive business results (excellent, very good, or good). For a three-year window between 2008 and 2010, however, those numbers plummeted with an all-time low in 2009 when just one in three respondents (34 percent) reported favorable business ratings. Those numbers increased slightly in 2010, but 2011 respondents gave the most favorable business ratings (43.4 percent positive) since 2007.

Another favorable indication is the accuracy demonstrated in yearly predictions and the subsequent results. With the exception of those predicting a fair year, responses from last year’s forecast results versus this year’s actual results are all within 5 percent, and most forecast discrepancies erred toward being overly pessimistic.

• Excellent: 1.6 percent forecast; 5.7 percent actual (+4.1 percent difference);

• Very Good: 12 percent forecast; 13.2 percent actual (+1.2 percent difference);

• Good: 24.8 percent forecast; 24.5 percent actual (-0.3 percent difference);

• Fair: 44.0 percent forecast; 34.9 percent actual (-9.1 percent difference); and

• Poor: 17.6 percent forecast; 21.7 percent actual (+4.1 percent difference).

From a regional perspective, producers in the Northeast were the most likely to report positive results with nearly six in 10 (58.3 percent) indicating positive business results in 2011, while approximately two-thirds (67.5 percent) of those in the South reported fair or poor results.

Small producers (under 500,000 tons per year) were the most likely to indicate positive business results, with the level of optimism diminishing in a direct correlation to increasing tonnage until hitting the large end of the spectrum with producers of more than 5 million tons per year. This group was slightly more inclined to report favorably, with one in three reporting favorable results, compared to three in four reporting fair or poor business results in the next largest production category (3 to 5 million tons per year).

In terms of operators experiencing changes in production quantities throughout 2011, an equal number said they’d increased and decreased production. It’s worth noting that, of those reporting an increase, the average increase was 25 percent higher production. Among those indicating a decrease, the average decrease was 19 percent. The largest gains were had among producers of crushed stone and sand and gravel (30.8 percent reported an increase) and among those in the North Central region (43.5 percent indicated higher production levels).

So what’s next?

While gains appear evident within pockets of the industry, several years of inertia are challenging to reverse. Looking forward in 2012, small improvements are being predicted in most categories. Comparing forecast projections from 2012 to those from 2011, 6.6 percent expect an excellent year (+5 percent), 12.3 percent expect a very good year (+0.3 percent), and 26.4 percent expect a good year (+1.6 percent). In terms of negative expectations, 35.8 percent expect a fair year (-8.2 percent), while 18.9 percent expect a poor year (+1.3 percent) in 2012.

Sand and gravel producers are the most concerned looking forward. Nearly nine in 10 (88.9 percent) expect a fair or poor year in 2012. Those working in the Northeast and North Central regions are the most optimistic with 66.6 and 52.2 percent, respectively, calling for positive business results. In terms of size, small operators are the most hopeful, with 68.4 percent of those producing up to 500,000 tons per year and 53.3 percent of those producing 500,001 to 1 million tons per year calling for positive results.

In terms of production quantities, sand and gravel producers are the most upbeat. Twice as many anticipate an increase in production compared to those who expect tonnage to decline.

Consistency is key from a regional perspective. The majority of operators in all four regions expect production quantities to remain about the same. That said, operators in the North Central region were the most optimistic with 34.8 percent anticipating an increase compared to 13.0 percent calling for a decrease. Producers in the South are still skittish on demand; they were the only region with more respondents anticipating a decline (20.9 percent) than an increase (16.3 percent).

Personnel matters

In 2011, employment levels were slightly more stable throughout much of the aggregate industry. Overall, 27.4 percent (9.6 percent fewer than in 2010) of respondents said the work force decreased throughout the year, while 20.8 percent said their work force grew.

Crushed stone and sand & gravel operators were the most likely to report having a smaller work force (41.0 percent), while sand and gravel operators were most inclined to boost their numbers (33.3 percent). Crushed stone only operators had the most stable work force segment with 58.3 percent indicating the size of their work force was about the same as during the previous year.

From a regional perspective, the South’s declining production levels were reflected in its staffing; 46.5 percent of operators there reported work force declines. The most growth was seen in the North Central region where 26.1 percent of respondents’ operations grew their numbers.

By worker category, other hourly labor was the category to experience both the highest increase (13.2 percent) and the highest decrease (27.4 percent). The number of women in the workplace grew, as it was the only category to report more work force expansion (10.4 percent) than contraction (6.6 percent).

Industry challenges

Competition for sales has dominated operator concerns during the last four years. While the number who ranked it as a major concern diminished this year (25.5 percent), nearly 60 percent more called it a minor problem. Taken as a combined total, almost 85 percent noted it as a challenge — 25 percent more than the next most widespread problem.

When asked how they were dealing with this issue, many respondents indicated that they have lowered prices to seal the deal, including break-even pricing. Some vertically integrated operators noted using package deals to streamline costs. Others say they are analyzing markets, implementing long-term strategic planning, and exploring new and growing markets. Customer service, customer contact, and a focus on quality are among the business strategies being employed to maintain customer loyalty.

Other concerns, such as regulatory compliance and aggregates availability, are increasingly important to this year’s respondents, but the dominance of competitive sales indicates that the aggregate industry — while in a better place than recent years — remains intensely focused on each job and each customer.

Improvements may be modest and regional, but they do, indeed, appear to be real. If these results and those forecast for 2012 bear out, then the aggregate industry needs to ensure that objects in motion stay in motion. From there, it’s a matter of increasing mass and velocity.

Methodology, Objectives, and Sources

The objective of the 2012 Aggregates Manager Forecast Survey was to determine business, production volume, spending, and workforce trends. In November 2011, Aggregates Manager e-mailed questionnaires to a random selection of readers in the crushed stone and sand and gravel, crushed stone-only, and sand and gravel-only industries. A total of 106 useable surveys were completed.

Better Roads editors step up and choose their “best of the best”

Buoyed by CONEXPO-CON/AGG 2011, this year brought with it a wide, innovative range of new equipment and products for the road construction and maintenance sectors. Many of these keen new introductions marched across the pages of Better Roads and www.betterroads.com . . . and rolled right into the marketplace where they will undoubtedly serve both serve contractors and agencies exceptionally well as they embrace the opportunities to come.

Upon reflection of the year that was, of the hundreds of product introductions editors reviewed and processed for our monthly New Road Products section, these are the 20 that most caught our collective eye for their industry significance, their ingenuity, their filling of a market need and/or their just plain ol’ coolness. Keeping the list to 20 is difficult. It means, for instance, not choosing some tremendous new products that are exciting and important to the construction industry.

We, the editors of Better Roads, set ourselves the goal of determining our Top 20 only; and to reach it we had to do a lot of talking, negotiating and decision-making. We had to examine and then re-examine our reasoning and our selections. Believe me, this was one intense job.

Today we proudly toast these products and the deserving companies that create, design, manufacture and market them. Moving forward, we’d like to know how you have been, are or will be able to use any of these “best of the best”. Any and all comments are not only welcome, but encouraged. Please drop us an e-mail over the coming year at mike.anderson@randallreilly.com or give us a shout at (205) 248-1310.

Arctic Snow and Ice

HD Sectional Sno-Pushers

Bergkamp

Mobile Stockpile Trailer

Case

DV207, DV210, DV213 Double-Drum Compactors

Caterpillar

CT660 On-Highway Truck

Caterpillar

 AP1000E, AP1055E Asphalt Pavers

Doosan

 Portable HP750e Electric Air Compressor

Dow

FASTRACK HE-2706 Resin

Ford

F-150 Eco-Boost Pickup Truck

GOMACO

4400 Barrier Machine

Gradall

XL 4100 IV Highway Excavator with AutoDrive

John Deere

460E Articulated Dump Truck

Maxwell Products

Novu Gap Meltable Crack Sealer

Power Pavers

SF-1700 Slipform Paver

Takeuchi

TB117e Electric Excavator

Terex

RS950B Reclaimer/Stabilizer

Terex

Hydra Platforms HPT 11/38

Vaisala

RoadDSS Value Calculator

Vogele

VR 600-2 Extending Screed

Volvo

G900B-Series Motor Graders

Volvo Trucks

VNM Daycab Natural Gas Option

BERGKAMP Less time hauling, more time paving

A single piece of equipment that will cut out the need to locate, access, secure and manage off-site material stockpiles? It may seem like a dream to some roadbuilding contractors, but it’s a reality thanks to asphalt pavement preservation equipment manufacturer Bergkamp. Debuted at CONEXPO-CON/AGG 2011, the Bergkamp Mobile Stockpile is a material-transfer and storage trailer that is pulled directly to the jobsite. There, trucks bring aggregate and emulsion from the supplier directly to the trailer, to which truck-mounted slurry seal or microsurfacing pavers can in turn connect and be fully replenished in less than 10 minutes. The main 21.5-cubic-yard hopper can either store or simultaneously transfer material via the unit’s 24-inch discharge conveyor. The use of multiple pavers on surface treatment jobs as essentially haul trucks between off-site stockpiles and the application site is eliminated, thus allowing fewer pavers to do more actual work in less time, says Bergkamp. This, too, will avoid the risk of overweight citations. The mobile stockpile trailer is compatible with most slurry seal and microsurfacing pavers on the market, the company says. For more information, visit www.bergkampinc.com

CASE

Renowned brand goes big on compaction

One of the construction equipment industry’s signature brands, Case isn’t just compact on compaction any longer. The company’s first large double-drum vibratory compactors, the DV207, DV210 and DV213 unveiled at CONEXPO-CON/AGG 2011 have drum widths of 57, 66 and 83 inches respectively. This product introduction moves the Case DV family beyond the utility class – the previous largest model had a drum width of 51.2 inches – and into product asphalt paving applications. With machine weights ranging from 16,226 to 28,726 pounds, the three new Case double-drum compactors have rear-mounted power trains that lower noise, vibration and heat for operators relishing “superior comfort for long workdays,” says Woody Ferrell, Case global product marketing manager. Dual, multi-function, directional controls on both sides of the swivel seat allow for machine operation from the left or right position in the rotating operator’s station. The Case vibratory system automatically starts when the drive lever is moved from neutral; it automatically stops when the lever is returned to neutral. For more information, visit www.casece.com/wps/portal/casece/product?product=CompactionEquipment&brandsite_brand=CaseCE&brandsite_language=en&brandsite_geo=NA

CATERPILLAR

On-highway vocational truck

The “yellow iron” customer is the Caterpillar customer, the company firmly believes. So with upwards to 30 percent of all Class 8 trucks sold being put into vocational applications, there’s no secret at where the new Caterpillar foray into the manufacturing, selling and servicing of on-highway trucks is taking dead aim. “It’s really about a company for the first time that focuses not just on a truck, but on the application of that truck in the construction business,” says George Taylor, director, Caterpillar Global On-Highway Truck Group. “How does it work with load-and-haul? How does it work with the fill operations? How does it interact with the construction machines? That’s really the direction we’re going, because we know our customers don’t use that truck by itself. Even if the construction company doesn’t own the dump trucks it uses, as often the case in paving operations, the continuity of technology may still influence the spec’ing of the trucks that will ultimately land the sub work from the project contractor, says Taylor. “It’s about trying to leverage that interaction between the two.” Beyond the Navistar-made Cat CT11 and CT13 engines available on the sleek CT660 set-back-axle model built for mixer, dump and heavy hauler uses, a 15-liter CT15 will be available in 2012, boosting engine output to the 550-horsepower range from the current maximum 475. The same engine options will be available on the set-forward-axle CT680 truck model, due out in first-quarter 2013 with the same choice of 116- and 122-inch bumper-to-back-of-cab configurations. For more information, visit www.cat.com/truck

Ford

F-150 EcoBoost: Our Light-Duty Pickup of the Year

Combine the new Ford EcoBoost engine’s prowess with the interior fit and finish, refined ride and overall handling of the venerable F-150 Crew Cab, and you have a pickup that rightly deserves to be named Better Roads’ Light-Duty Pickup of the Year. So proclaims Bruce W. Smith, editor of ProPickup, a sister Randall-Reilly publication. “I used to think there’s no substitute for cubic inches when it came to a stellar work pickup. I have been proven wrong – twin-turbo technology is a substitute,” explains industry veteran Smith. “After spending a week behind the wheel of the 2011 F-150 EcoBoost, dressed up in the Lariat trim, it’s hard to imagine any other half-ton in a contractor’s work fleet. Ford’s twin-turbo, direct-injected, 365-horsepower, 3.5-liter V-6 is more powerful than most 5-liter V8s, pulls like a diesel, and delivers class-leading fuel economy.” With a fuel capacity of 26 gallons, the six-speed-automatic F-150 EcoBoost is EPA-rated at 16 miles per gallon in the city/21 highway; Smith’s similar observations were 15.4 city/19.4 highway. Towing capacity of the truck is 5,000 pounds on the ball; 11,300 pounds with a weight-distributing hitch. For more information, visit http://www.ford.com/trucks/f150/2011/experiencef150/

JOHN DEERE

New artic truck will run like a Deere

The first all-Deere articulated dump truck (ADT) will also be the largest Deere-branded “artic” ever. “Customers who now have 40-ton artics can use the 460E to get one more full excavator bucket into the truck,” says Mark Oliver, ADT product marketing manager for John Deere Construction and Forestry. Announced at CONEXPO-CON/AGG 2011, the 46-ton-capacity truck will be the first ADT completely designed by John Deere, incorporating a Deere 13.5-liter engine, Deere wet-clutch axles and a ZF drive line. Prior John Deere articulated trucks have a Bell Equipment heritage, an alliance that will continue with some of Deere’s smaller models. The first of Deere’s E-Series models, the 460E will have automated traction controls, taking the guesswork out of when to use differential locks and allowing newer operators to get up to speed more quickly. In difficult ground conditions, the system will automatically control the axle differential locks and inter-axle differential lock. An on-board scale will let operators know when the truck is loaded to capacity, and the JDLink telematics system will allow monitoring of material moved each day. For more information, visit www.deere.com/wps/dcom/en_US/products/equipment/articulated_dump_trucks/articulated_dump_trucks.page

GOMACO

Barrier to the right, barrier to the left

As road contractors know all too well, equipment design hasn’t always been entirely conducive to placing material where it is precisely required. Well, GOMACO typically has yet another complete solution for crews working with concrete. Shown for the first time at CONEXPO-CON/AGG 2011, the GOMACO 4400 ultimate barrier paver has a new frame design for right- and left-side slipforming. To accommodate operator control and visibility to the working areas, the new Glide control console slides from side to side. When not in operation, the operator’s console locks safely away in the center position. Also new, GOMACO’s Barrier Hook-and-Go system allows barrier molds up to 39.4 inches in height to be quickly mounted on either side of the machine. The barrier molds themselves are designed for proper vibration and consolidation of material, topped off by GOMACO’s exclusive trailing stainless steel for superior finishing, the company says. A side mount is available to accommodate larger barrier. The 4400 unit has symmetric steering and proprietary G+ controls operated in multiple languages. For more information, visit http://www.gomaco.com/Resources/4400barrierpaver.html

DOOSAN PORTABLE

An electrifying compressor

Talk about clean air! At CONEXPO-CON/AGG 2011, Doosan Portable Power rolled out a portable, highway-towable compressor that can deliver 750 cubic feet per minute of free-air . . . and no emissions. As compared to the diesel engine of the established HP750 model, a three-phase electric motor powers the new HP750e, controlled by a liquid-cooled, variable-frequency drive system. Features include an intuitive full-color digital display and easy-to-use interface that can be wirelessly monitored. An optional full gauge package is customizable and has an LED backlighting system for enhanced visibility. Other options include the IQ System aftercooler for drip-free moisture control, dual-pressure regulation and up to one 2-inch and three 1.25-inch air valve additions. For more information, visit http://www.doosanportable.com/americas/products/compressors/Pages/default.aspx

TEREX

Largest reclaimer yet is ready to roll

Faster, bigger, stronger: A new Olympics motto, perhaps? Terex Roadbuilding’s newest top-of-the-line reclaimer/stabilizer, indeed! Boasting 30-percent-plus more horsepower than the next most powerful competitor, the RS950B is capable of cutting deep asphalt at unparalleled speeds. Why a 950-horsepower reclaimer/stabilizer? “It’s strictly for production,” it was explained to visitors to the massive Terex outdoor booth at CONEXPO-CON/AGG 2011. The four-wheel-drive, four-wheel-steer unit can, with its choice of high- and low-range working speeds, operate at up to 210 feet per minute. During a heavy reclamation application requiring six or even eight inches of asphalt to be cut, the RS950B is claimed to produce at twice the rate of the 600-horsepower RS600 size model, the previous largest in the active Terex reclaimer/stabilizer family. Powered by a Caterpillar C27 diesel engine, the RS950B offers a choice of four cutter speeds – 102, 131, 163 and 200 rpm – and bi-directional cutting thanks to the unique housing’s front and rear doors. Compared to hydrostatic systems, Terex’s V-belt power-band cutter drive provides up to 25-percent more efficient operation. The RS950B’s standard 8-foot-wide cutter has 218 tungsten carbide teeth capable of cutting 16 inches deep. Available rotors allow for the option of a 10-foot-wide cutter, or a 58-inch-diameter mandrel for 20-inch-deep cuts. For more information, visit http://www.terexrb.com/Content.aspx?pgID=437

DOW

A Fast response to traffic paint shortage

When a paint supply crisis hit across the nation for Departments of Transportation and highway contractors alike, Dow Coating Material’s research and development team stepped up. “As we learned again last year, shortages of traffic paint can have a direct effect on public safety, and that’s not acceptable,” explains Stan Cook, Dow traffic paint marker manager. “When the supply crisis struck, we accelerated our high-efficiency development schedule in order to help customers and DOTs meet a challenge that had become a crisis.” The result, displayed at the American Traffic Safety Services Association convention and expo in February, is the new FASTRACK HE-2706 resin with higher pigment binding efficiency, higher pigment loadings and a reduction of titanium dioxide. The product does not sacrifice drying time or properties such as “sprayability,” visibility, durability or stability. It provides a reduction of up to 30 percent in the amount of latex necessary in waterborne traffic marking paint. For more information, visit www.dow.com/products/product_detail.page?display-mode=tds&product=1120397

MAXWELL PRODUCTS

Melt away patch pack

So, you’ve got a small patch job or a depression around a drain or curb, where hot mix is impractical and crack seal is ineffective. What can you do about it, right? Well, Nuvo Gap from asphalt and concrete sealant manufacturer Maxwell Products offers a permanent, rubberized, hot-pour solution that, best of all, is packaged in a meltable container designed to absorb completely into the product upon application. With Poly-Skin, there’s no need for opening or even cutting the product packaging on site. Nuvo Gap’s combination of high-performance sealant and engineered aggregates forms a self-leveling, load-bearing, weather-resistant bond, ideal for wide cracks and other large gaps in pavement. For more information, visit http://www.nuvosealants.com/product_gap.php

VOLVO

New motor graders built to bear down

It’s difficult to argue when Volvo Construction Equipment says “what really matters” for grader productivity is blade down pressure and blade pull force. Well, with an emphasis on overall machine balance and distribution of the main grader components, the company’s new G900B-Series motor graders have the highest blade down pressure in each weight class. Using larger-displacement engines with cooled exhaust gas recirculation technology to meet Tier 4 Interim emissions requirements, each of the G930B, G940B, G960B and all-wheel-drive G946B motor grader models can be driven by either the standard HTE840 transmission with eight forward and four reverse gears or the optional HTE1160 transmission with 11 forward and six reverse gears. These Volvo transmissions boast three and eight power curves respectively, matching power output to the traction available. Each also uses the “shuttle shift” system to move between forward and reverse without the operator needing to stop the machine or use the inching pedal. The four models in the new Volvo motor grader series range 34,520 to 38,709 pounds in operating weight. For more information, visit http://www.volvoce.com/constructionequipment/na/en-us/products/motorgraders/Pages/introduction.aspx

GRADALL

Park the lowboy for this excavator

An excavator capable of reaching speeds even greater than those permitted on many local roads: If that isn’t the best definition of a highway excavator, then what is? The Gradall XL 4100 IV comes equipped with the new AutoDrive system, featuring a six-speed automatic Allison transmission. Powered by a 245-horsepower Mercedes Tier 4 Interim engine, the new XL 4100 IV telescoping excavator reaches speeds of 60 miles per hour on the highway. Once arrived at the jobsite, the AutoDrive’s new transfer case allows the wheeled excavator to be repositioned – at a maximum 5 miles per hour – from the excavation operator’s seat located in the upperstructure cab. Along with the new XL 4100 IV, available with either a 6×4 or 6×6 drivetrain, Gradall is introducing a yellow paint scheme designed to increase machine visibility. Maximum boom reach at grade is 30 feet 3 inches, maximum dig depth is 20 feet 3 inches and maximum loading height is 17 feet 2 inches. The boom crowd force is rated at 21,940 pounds and, opposite to conventional excavators, it remains constant throughout the dig cycle. For more information, visit www.gradall.com/excavator-models/en/highway_wheeled.html

POWER PAVERS

Less than full-size slipform paver

Why fire up a large piece of equipment when, frankly, the available load just doesn’t merit so? With its new compact slipform concrete paver model, Power Pavers offers an economical solution to a market issue based interestingly enough on material supply. “With the ability to pave up to 7.5 meters (24 feet 7 inches) wide, the SF-1700 was developed to react to the contractor demand for two-pass paving in many highway applications,” says Fred Hite, general manager of the Power Pavers Inc. subsidiary of Power Curbers. “In many developing countries, concrete supply is an issue, so paving in two passes is more practical than one pass.” By reducing the engine size and mainframe width of the company’s mainstream SF-2700 model, Power Pavers was able to develop the SF-1700, which comes standard with a 160-horsepower Cummins engine, 12 Wyco vibrators, and a spread auger and tamper bar. Within a month of introduction, Power Pavers had placed units in three countries, says Hite, and “we are getting great reports from our customers who have put them to work.” For more information, visit http://www.powerpavers.com/products/slipformpavers/

TAKEUCHI

Electric excavator takes center stage

One of the operational advantages to the most compact of hydraulic excavators is the ability, size wise, to be put to work indoors as well as the traditional outdoors. With Takeuchi’s introduction of a “world’s first” at CONEXPO-CON/AGG 2011, the use of a hydraulic excavator in an environmentally-sensitive enclosed space just got much less tricky. The first fully electric-powered excavator, the TB117e boasts zero exhaust emissions and reduced vibration and sound levels that will suit it for demolition, foundation and clean-up jobs in hospitals, schools and other sensitive, highly-congested areas. The undercarriage retracts from the stable full-width 51 inches to a minimum of 39 inches for passage through doorways. The TB117e has a lithium-ion battery that, when fully charged, can power up to six hours of uninterrupted performance that, says Takeuchi, is on par with its established 1.6-metric-ton TB106 excavator model. Capable of traveling at 2.9 miles per hour, the TB117e boasts bucket breakout force of 4,079 pounds, arm crowd force of 1,704 pounds and traction force of 3,801 pounds. For more information, visit http://www.takeuchi-us.com/www/blog/viewpost/43

VöGELE

Screed stretches but retains paving integrity

Going wide doesn’t have to mean losing shape for asphalt paving contractors, thanks to a new rear-mount Vögele screed introduced at CONEXPO-CON/AGG 2011. For use on Vision Series pavers from Wirtgen’s Vögele brand, the VR 600-2 extending screed offers vibration across the full paving width, up to 28 feet. The screed’s basic width is 10 feet, extending hydraulically up to 19 feet 8 inches and then, with bolt-on extensions fitted, an additional 8 feet 4 inches. The three-section telescoping tube, allowing infinitely-variable screed width control, remains rigid and robust even at maximum extension. Each individual section never extends by more than half. When sloping the extensions on jobs, only the frame of the screed extension is slanted, leaving the guide system horizontal at all times and providing maximum rigidity. A three-point suspension prevents the extensions from jamming or pinching. With ErgoPlus, the screed operator has the placement of asphalt literally at his fingertips with waterproof push bottoms enclosed in a raised ring for touch identification even when wearing gloves. Crown and extension height adjustment are set independently. For more information, visit http://www.wirtgenamerica.com/us/products/voegele/screeds/Screeds.php

ARCTIC SNOW & ICE CONTROL

A solution to the ups and downs of plowing

The fewer the number of passes a snow removal contractor requires to clear a lot or street, the quicker he’s off to his next job . . . and next paycheck. Such is the bottom-line appeal to HD Pushers, a boxed snow-removal attachment product line created by the Sectional Sno-Pusher division of Arctic Snow and Ice Control Products. The patented moldboard design features individual 32-inch-wide sections equipped with spring-loaded trip edges. Each section responds to changes in the pavement, moving up and down on its own, allowing the loader attachment to contour to uneven surfaces and reduce the amount of re-plowing required. As compared to competitive plows or pushers that have rubber or polyurethane cutting edges, AR-400 hardened-steel edges are used on each individual moldboard section. These are designed to scrape down to the pavement to remove snow and ice in a single pass. Each section of moldboard is individually mounted to the attachment’s mainframe with engineered polyurethane blocks, requiring a section only to be unbolted, removed and replaced if damaged. For more information, visit www.sectionalplow.com

CATERPILLAR

E-missions covered by asphalt pavers

Wherever the paving job is, the new Caterpillar E-Series highway-class asphalt pavers are out in front on emissions requirements. The first asphalt pavers to meet Tier 4 Interim standards, courtesy the Cat C7.1 ACERT engine, the 10-foot-class AP1055E tracked paver and the sister AP1000E wheeled model are also available with the C6.6 ACERT engine for markets where only Tier 3 is required. Both engine models deliver 225 horsepower. To meet Tier 4 Interim emissions requirements, the C7.1 engine combines the Cat NOx Reduction System and Cat Clean Emissions Module. Each paver model has a dual operating station, equipped on the left side with the Advisor Monitoring System, an interactive, text-based, multi-language interface packed with fuel-saving features. These include an engine speed control that automatically adjusts engine rpm when the propel lever moves to and from neutral, and an eco-mode that lowers engine speed to 1,650 rpm when less demanding operating conditions exist. The display provides project-planning calculators, a start-up checklist, engine operating conditions and service code information. On the tracked AP1055E paver, the Mobil-Trac undercarriage uses large oscillating bogies and hydraulic accumulators to overcome surface irregularities. For more information, visit

http://www..cat.com/equipment/paving-equipment

TEREX

Platform-mounted truck does not require CDL

Moving a formidable under-bridge access platform from jobsite to jobsite just got considerably easier, thanks to Terex Roadbuilding’s first truck-mounted cross model – matching the trailer platform with a truck chassis. Being within the 26,000-pound maximum gross vehicle weight limit, the HPT 11/38 does not require a driver/operator with a Commercial Driver’s License (CDL). The telescopic platform is 38 feet long and a maximum 42 inches wide and, upon arrival at the jobsite, is self-propelled into position by hydrostatic drive. Single-lane deployment takes a mere five minutes. Platform weight capacities of 1,000 pounds total and 500 pounds at the end are enough to securely accommodate multiple workers with tooling. Offering a maximum 16 feet of lowering depth and 180-degree rotation, the under-bridge access platform is ideal for applications ranging from bridge inspection and restoration to stripping operations and utility work. For more information, visit

 http://www.terexrb.com/Content.aspx?pgID=430

VOLVO TRUCKS

Daycab tractor can run on natural gas

The United States has plenty of natural gas . . . and truck fleets have an option to put it to good use. The Volvo VNM Daycab tractor model now comes with a factory-installed natural gas option, ideal for “localized or closed-loop operations,” says Ron Huibers, Volvo Trucks’ senior vice president, sales and marketing. Such applications “present a great opportunity for companies to utilize our nation’s abundant domestic supply of natural gas,” says Huibers. “Volvo is already delivering the cleanest trucks in the world in terms of regulated emissions, and now we’re offering an alternative fuel option to move our nation’s goods while emitting less carbon dioxide.” The tractor is powered by a 9-liter, 320-horsepower Cummins Westport ISL G engine that uses clean-burning compressed or liquefied natural gas. The heavy-duty engine, generating 1,000 foot-pounds of torque, requires only a three-way catalyst to meet EPA 2010 on-road emissions standards. For more information, visit http://www.volvotrucks.com/trucks/na/en-us/products/vn/vnm/Pages/overview.aspx

VAISALA

Weather moves

Wondering what the true benefits of a Road Weather Information System (RWIS) would be for your agency? Intelligent transportation systems manufacturer Vaisala has a free, quick way for you to find out. The RoadDSS Value Calculator in an online tool that evaluates potential cost and community savings to using various RWIS or road decision support systems. The calculator asks 12 questions about road maintenance operations. Once the user has input infrastructure and cost information, the calculator uses embedded algorithms to produce calculated savings based on referenced study findings. The report provides a breakdown of all direct and indirect savings, including such safety factors as accident reductions and environmental factors such as reductions in carbon and other pollutants. A user can adjust any of the information input to tailor the end report to reflect the agency’s needs. For more information, visit www.vaisala.com/roaddsscalc

Nanotech era draws closer

By Tom Kuennen, Contributing Editor

Nanotechnology offers long-term promise to boost performance of our highway, road and bridge infrastructure. New research is expanding and new applications are materializing. More recently, the long-term environmental impacts of nanomaterials are being studied. But implementation is going to take a long time.

The impact of nanotechnology on highway, road and bridge transportation infrastructure is just beginning. Nanotechnology involves the characterization, engineering and fabrication of matter at the molecular nanoscale, to improve existing products and to make feasible new materials and processes.

Nanoscale crystal seeds speed up concrete hardening. BASF’s X-Seed hardening accelerator makes additional heat superfluous and the concrete is particularly strong and durable. Magnification 960:1 (by 12 cm in width).

Nanotechnology embraces the nanoscale; that is, the range of dimensions from approximately 1 nanometer to 100 nanometers (1 to 100 billionths of a meter). One nanometer is 100,000 times smaller than the width of a human hair. That’s a molecular domain in which devices and systems exhibit properties that aren’t seen at larger scales. In that domain of quantum physics, clusters of atoms and molecules exhibit properties quite different from those found at larger scales. These properties have applications for pavement and bridge infrastructure.

“Nanotechnology should not be implemented in the pavement engineering arena merely because it is a new technology,” states Wynand Jacobus van der Merwe Steyn, Department of Civil Engineering, Tshwane University of Technology, Pretoria, in his paper, Development of Auto-Luminsecent Surfacings for Concrete Pavements. “[T]he application of nanotechnology should allow the engineer to deliver a better product to the client. This may, for instance, be a more cost-effective product, a more technologically suitable product or a safer product.”

Nanotechnology can focus on improving the general properties (e.g., strength, durability) of current materials, the ability to use marginal materials, or the novel application of nanotechnology to enable a safer transportation environment, Steyn says.

Nanomaterials and Construction

Nanomaterials offer significant advantages for the construction industry at large, from making more durable concrete to self-cleaning signs or windows. “The advantages of using nanomaterials in construction are enormous,” says Pedro Alvarez, chair of the Department of Civil and Environmental Engineering at Houston’s Rice University. “When you consider that 41 percent of all energy use in the U.S. is consumed by commercial and residential buildings, the potential benefits of energy-saving materials alone are vast.”

But widespread use in building materials comes with potential environmental and health risks when those materials are thrown away. Those are the conclusions of a study published by Rice University engineering researchers in the July 2010 issue of ACS Nano.

“[T]here are reasonable concerns about unintended consequences,” Alvarez says. “The time for responsible lifecycle engineering of man-made nanomaterials in the construction industry is now, before they are introduced in environmentally relevant concentrations.”

In fact, in a 2010 report, Nanomaterials in the Construction Industry: A Review of Their Applications and Environmental Health and Safety Considerations, Alvarez and co-authors Jaesang Lee, a postdoctoral researcher at Rice, and Shaily Mahendra, an assistant professor at UCLA, find that nanomaterials will likely have a greater impact on the construction industry than any other sector of the economy, following biomedical and electronics applications.

Nanomaterials, they find, can strengthen both steel and concrete, keep dirt from sticking to windows, kill bacteria on hospital walls, make materials fire-resistant, drastically improve the efficiency of solar panels, boost the efficiency of indoor lighting and even allow bridges and buildings to “feel“ the cracks, corrosion and stress that will eventually cause structural failures.

But the authors warn of potential adverse health and environmental effects of widespread use of nanomaterials. In some cases, the very properties that make the nanomaterials useful can cause potential problems if the material is not disposed of properly. For example, titanium dioxide particles exposed to ultraviolet light can generate molecules called “reactive oxygen species“ that prevent bacterial films from forming on windows or solar panels. This same property could endanger beneficial bacteria in the environment.

FHWA Coordinates Research

The Federal Highway Administration (FHWA) has been studying applications of nanotechnology to highway infrastructure for more than a decade.

In 2009, FHWA’s Exploratory Advanced Research (EAR) program hosted a workshop to identify interests and capabilities for nanoscale research that can be applied to highways. The workshop attracted experts from FHWA, university transportation research centers, federal labs and other organizations that are conducting nanoscale research.

The workshop helped shape the scope of FHWA’s further investment in nanoscale research, and supported the development of strategic roadmaps that could outline funding needs for future nanoscale research for highway infrastructure.

“We expect the nanoscale workshop to lead to an overall increase in research targeted at highway program needs,” says David Kuehn, EAR program team director at FHWA. “The workshop was an ideal opportunity to collaborate and leverage nanoscale technology that is being developed for other industries and to accelerate our ability to solve long-term highway research questions.”

“There are multiple potential nanoscale applications in highways,” FHWA says in a 2010 report on the workshop, Nanoscale Approaches for Highway Research. “For example, concrete is a material containing pores on a nanoscale, a result of the chemical reaction between cement and water. Repeated exposure to deicing chemicals causes oxidation, cracks and long-term deterioration to occur in the structure. Utilizing nanotechnology to create smart self-healing materials and structures could lead to less-frequent and faster construction, as well as to increased durability and improved performance, all helping to prevent catastrophic failure.”

Nanotechnology’s ability to produce minuscule MEMS, or microelectronic and mechanical systems, would permit stakeholders to constantly monitor materials, and also could offer improved predictive performance models. “During construction, nanotechnology can allow for embedding increasingly smaller sensors throughout a structure or pavement,” FHWA says. “These sensors could be used for long-term monitoring of corrosion and could offer an invaluable tool in monitoring bridges. By using a car-mounted data reader, information from the embedded sensors could then easily and safely be collected as the vehicle passes.”

As Alvarez, Lee and Mahendra observe, some of this research should be aimed at the environmental aspects of widespread use of nanotechnology, FHWA says. There is concern that unleashing these products on a widespread basis could have unanticipated consequences like something out of a science fiction novel.

Yet nanotechnology in transportation infrastructure also offers environmental benefits, FHWA observes. “[Nanomaterials have the] ability to monitor mobile source pollutants during construction and operations by using nanoscale devices to bind with road-based pollutants,” FHWA says. “Low-cost environmental sensors could monitor the air, water and soil quality, and the technology could allow large-scale monitoring of the operation to continually map pollution levels.”

In a new line of research, nanomaterials such as thin-film technologies may boost use of recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP), in addition to reducing alkali-silica reactivity (ASR) in concrete.

“Nanoscale research could lead to an increased use of recycled materials in pavements through a better understanding of bonding at the boundaries of different materials and the design of very thin coatings to improve the workability and durability of recycled materials, which would also help to reduce costs,” FHWA says. “Nanoscale research also could result in the development of smaller, lower-cost sensors, which would use substantially less energy. Self-powered sensors also would contribute to the efficiency and reduced environmental impact of the highway network.”

Concrete Leads Nanoresearch

By far, the most activity in nanotechnology research for pavement and bridge infrastructure has taken place in the concrete industry. There, research is aimed at optimizing concrete strength and durability using nanomaterials, and condition monitoring via MEMS imbedded in the concrete matrix.

For years, the minuscule size of a particle of microsilica admixture has benefited concrete, as the smaller the silica particle size, the greater the surface area that is presented for reaction within the curing concrete. The much smaller size of nanoparticles now makes possible a geometric increase in performance, and that’s one of the areas of research.

Research in concrete nanotechnology has been well-organized. A workshop at the University of Florida in August 2006 was attended by more than 70 participants, with more than 30 presentations, and focused on the development of a Roadmap for [Nanotechnology] Research for Concrete-Based Materials. The roadmap is destination-oriented, with clearly defined outcomes that will greatly enhance concrete technology and the uses of concrete in structures, including housing, bridges, tunnels and pavements.

That 2006 roadmap identifies research needs such as:

• development of high-performance cement and concrete materials as measured by their mechanical, durability and shrinkage properties;

• development of sustainable and safe concrete materials and structures through engineering concrete for different adverse environments, reducing energy consumption during cement production, and enhancing safety with nanoengineering of concrete materials;

• development of intelligent concrete materials through the integration of nanotechnology-based, self-sensing and self-powered materials and cyber infrastructure technologies;

• development of novel concrete materials through nanotechnology-based innovative processing of cement and cement paste; and

• development of fundamental multiscale model(s) for concrete through advanced characterization and modeling of concrete at the nano-, micro-, meso- and macroscales.

The workshop was followed with a September 2007 conference in Arlington, Va. And, in 2008. a Center for Nanotechnology in Cementitious Systems (CNCS) was created at Iowa State University. The CNCS uses nanotechnology to improve sustainability and performance of concrete roads and structures. The cross-disciplinary nature of the center opens the door to exciting research in this new area, including nano devices that could one day monitor and report on the state of hydration in a mixture and correlate that with the risk of cracking, or predict when traffic can be placed on a pavement.

Other nano-based materials or devices could be used to modify or control the rate of hydration to allow for changes in construction practices or prevent weather-related damage during construction, CNCS says.

In the future, CNCS researchers hope to support 10 graduate students through research projects. Initial projects are being developed, including analysis of the effects of shrinkage-reducing admixtures on the morphology of hydrated cement paste and the properties of air voids entrained in the mixture.

Finally, in May 2010, the First International Conference on Nanotechnology in Cement and Concrete was held in Irvine, Calif. More than 100 delegates from 17 countries and 27 states heard 37 technical papers covering nanotechology in concrete.

Concrete Nanoscale

Nanomaterials can boost strength and resistance to permeability in concrete, according to Celik Ozyildirim, P.E., Ph.D., principal research scientist, and Caroline Zegetosky, graduate research assistant, Virginia Transportation Research Center (now Virginia Center for Transportation Innovation and Research), in their paper Exploratory Investigation of Nanomaterials to Improve Strength and Permeability of Concrete.

“Concrete containing various supplementary cementitious materials (SCMs) such as silica fume, fly ash and slag has improved properties,” they write. “Nanomaterials, new SCMs with possible applications in concrete, have the smallest particle size (less than 100 nm). Nanomaterials are reactive because of the small size and large surface area of the particles, and they have great potential in improving concrete properties such as compressive strength and permeability.”

Ozyildirim and Zegetosky studied a variety of nanomaterials in concrete and compared them to conventional concrete, and concrete containing common SCMs. “The potential benefits of using nanomaterials over other SCMs are high reactivity and cost-effectiveness; in addition, smaller amounts are necessary, resulting in less cement replacement,” they write.

Concretes containing nanosilica and nanoclay were prepared in the laboratory, and compared to concretes containing conventional silica fume, fly ash, slag or only Portland cement. Specimens were tested for compressive strength and permeability. The microstructure of selected concretes with improved compressive strength and permeability was analyzed to explain the improvements.

“The results of this study indicate that some of the nanomaterials tested have potential in concrete applications,” Ozyildirim and Zegetosky write. “The microstructure of the nanosilica concrete was denser and more uniform than the conventional concrete microstructure. In addition, the nanosilica had the largest improvement in both compressive strength and permeability among the nanomaterials tested.”

Download their study from the Virginia DOT at virginiadot.org/vtrc/main/online_reports/pdf/10-r18.pdf

Nanocrystals and Concrete

The private sector has been quick to lead the way to nano-enhanced concretes. For example, a new product, X-Seed crystals from BASF, makes concrete cure faster and reduces carbon emissions.

X-Seed has innovated production of precast-concrete components by serving as a curing accelerator, which the company says not only allows precast concrete units to be produced more rapidly and in better quality, but considerably reduces energy consumption and the associated emission of carbon dioxide (CO2) greenhouse gas.

Cement is produced by pyroprocessing limestone, clay and minerals at high temperatures to produce cement clinker. Pyroprocessing consumes enormous amounts of energy, and releases large amounts of CO2 from combusting the fuel (principally coal or natural gas) and from the chemical reaction the combustion enables. Finally, the coarse-grained clinker is ground into a fine, gray cement powder that hydrates after mixing with water. Calcium silicate hydrate and other compounds crystallize out of the cement during this process to form a compact stone matrix in which aggregates and sand are embedded.

Concrete products are manufactured by placing the uncured concrete mix into forms. Only when the concrete has cured sufficiently can the mold be opened and the component removed. At ambient temperatures (68 degrees F) it can take up to 12 hours to cure, which is valuable production time, during which the formwork cannot be reused. To speed production, the mold often is heated with steam. Although this accelerates production, it also demands much additional energy. Moreover, this treatment can lead to internal thermal stresses, discolorations and a coarser surface of the finished concrete part.

“X-Seed makes heat curing, with all its disadvantages, largely superfluous,” says Dr. Michael Kompatscher, responsible for BASF’s European precast concrete component market. “With this additive, concrete hardens just as fast at 20 degrees C (68 degrees F) as it otherwise does at 60 degrees C (140 degrees F), by a adding something that’s already present in the concrete anyway – calcium silicate hydrate (CSH).”

Countless millions of tiny CSH crystals with a diameter of several nanometers are suspended in liquid in X-Seed, BASF says. Because of their nanosize, more very homogeneously distributed crystallization seeds can be accommodated in the same mass, and thereby promote faster growth. When the concrete cures, further molecules from the cement can attach themselves to these CSH “seeds.” The resulting crystals grow more densely and finally interlock to form the compact cement stone.

When conventional cement hydrates, the CSH seeds first have to form spontaneously from several molecules released from the cement, which accidentally come into contact with each other. X-Seed negates this first barrier to crystallization by providing an excess of these tiny crystal seeds. Another factor is that the CSH crystals form in a more homogeneously distributed manner.

Both these effects of the synthetic crystal seeds halve the time to formwork removal at 68 degrees F from about 12 to six hours, without any detectable differences in the final product, BASF says.

Zeolites and WMA

Warm-mix asphalt (WMA) technologies are a family of processes that produce low-energy asphalt mixes that can be placed at significantly lower temperatures than conventional hot-mix asphalt. At least one additive for warm-mix asphalt operates at the nanoscale, Aspha-Min.

Zeolites are nanoporous crystalline alumino-silicates with important attributes. A zeolite is a constituent of a group of commercially valuable minerals – metamorphosed crystals of hydrated aluminum silicates – of interest to industry for a variety of applications. Zeolites have large vacant spaces or cages in their structures that allow space for large, positively charged ions such as sodium and potassium, and even entire molecules such as water.

Aspha-Min is a synthetic zeolite compound, which releases water (H20) into the asphalt mix to improve workability at lower temperatures. Aspha-Min is available as a very fine, white-powdered form in bags or in bulk for silos. The percentage of water held by the zeolite is 21 percent by mass and is released in the temperature range of 212 to 392 degrees F.

By adding 0.3-percent Aspha-Min to the preheated mixture of sand and stone at the same time liquid asphalt is being introduced, a water-based vapor is created. The water released from the crystal causes the binder to expand to a kind of foam, permitting better workability and coating of aggregates at lower temperatures. Tests indicate that 54 degrees F reduction in temperature equates to a 30-percent reduction in fuel energy consumption.

Thanks for the MEMS

Nanotechnology for transportation infrastructure goes beyond engineered materials, into appliances manufactured at the nanoscale. These nanotechnology-driven sensors and instruments – microelectronic and mechanical systems, also called microelectromechanical systems (MEMS) – have the ability to detect motion and monitor corrosion, cracking and performance of structures and pavements under service loads and conditions.

In their 2008 paper, Applicability of Microelectronic and Mechanical Systems (MEMS) for Transportation Infrastructure Management, investigators Kelvin C.P. Wang and Qiang Li, Department of Civil Engineering, University of Arkansas-Fayetteville, describe the application of MEMS for pavements and bridges.

“With the tremendous advancement in technology, it is possible to employ devices embedded in structural members for real-time monitoring of infrastructure health,” they say. “Micro-electromechanical systems are miniature sensing or actuating devices [that] can interact with their environment to either obtain information or alter it. With remote query capability, it appears such devices can therefore be embedded in structures to monitor distresses such as cracking.”

MEMS merge the functions of sensing and actuating with computation and communication to locally control physical parameter at the micro-scale, yet cause effects at much grander scales, they observe. MEMS as devices have static or movable components with some dimensions on the scale of a micrometer, and can be either sensors, actuators or passive structures.

“Sensors are transducers that convert mechanical, thermal or other forms of energy into electrical energy; actuators do the exact opposite,” Wang and Li write. “Passive structures are devices in which no transducing occurs. A fourth classification, hybrid systems, is used for specialized applications. Micromachining and integrated circuit technologies are the foundation of sensors and actuators as well as of MEMS or microsystems.”

MEMS produce smart materials and structures technology, and their applications include structural control, condition or health monitoring, damage assessment, structural repair, integrity assessment and more recently in asset management, preservation and operation of civil infrastructure, they write. “The potential benefit here is improved system reliability, longevity, enhanced system performance, improved safety against natural hazards and vibrations, and a reduction in lifecycle cost in operating and managing the infrastructure. There is no doubt MEMS can . . . assist engineers in infrastructure management to have real-time or quasi-real-time information on the health of the infrastructure.”

In bridges, MEMS technologies are well-suited to improve the performance, size and cost of sensing systems, they say. “MEMS can be used in both monitoring and testing of transportation infrastructure systems,” they write, adding applications in bridge engineering are underway.

In pavements, MEMS have the capability of supplementing, if not replacing, nondestructive testing of pavement condition, they suggest. “Recently, vigorous efforts have been devoted into developing sensing technologies and nano-technology in infrastructure condition monitoring,” write Wang and Li. For crack monitoring purposes, a MEMS transducer has been developed for an ultrasonic flaw detection system, which can be used to detect the initiation of a crack.

Geometrically smaller size of nanoparticles increases the relative surface area available to react with cement in concrete.

Also, networks of nanosensors embedded in roadways could provide real-time information to better manage congestion and incidents, or to detect and warn drivers about fast-changing environmental conditions such as fog and ice. “In recent years, more and more attention has been paid to MEMS-based moisture sensors,” they write. It’s clear that MEMS will play a big role in the intelligent highway systems of the future.

Nanotechnology is leading to self-cleansing signs. The so-called “lotus effect” – which describes the self-cleansing surface of the lotus leaf, which takes place at the molecular level – is being replicated in lotus effect-based self-cleansing nano materials into traffic and work zone signage, and in particular traffic-control devices, which require labor-intensive periodic washing to remove road grime and enhance visibility.

Cleaner air from pavements: Titanium dioxide nanoparticles in both concrete and asphalt pavement surfaces have the ability to remove – via photocatalytic reaction – nitrogen oxides and sulfur dioxide from the atmosphere.

“On a hydrophobic, easy-clean surface, particles of dirt are just moved around by moving water, but on a lotus-effect surface, dirt and grime are collected by water drops and rinse off,” Wang and Li write. “Coatings that mimic the properties of the lotus leaf may well lead to signs that shed dirt and never need washing.”

Thin Film Technologies

Nanoscale research could lead to an increased use of recycled materials in pavements through a better understanding of bonding of different materials, and the design of very thin coatings to optimize use of reclaimed materials.

In their 2010 Transportation Research Board paper, New Possibilities and Future Pathways of Nanoporous Thin Film Technology to Improve Concrete Performance, Jose F. Muñoz of the Department of Material Science and Engineering, University of Wisconsin–Madison, and Richard C. Meininger and Jack Youtcheff of the Pavement Materials and Construction Team at FHWA’s Turner-Fairbank Highway Research Center, find that nanoporous thin films (NPTFs) may improve the interfaces between aggregate and cement paste.

“Aggregates are often considered as inexpensive inert filler material in concrete,” the authors write. “However, the mixture of the aggregate with the cement paste creates one of the most vulnerable areas of concrete, the interface of aggregate and cement paste. The judicious application of nanoporous thin films on the aggregate’s surface is an effective way to improve those interfaces.”

The most recent work on concrete shows that the use of different types of NPTF can induce changes in different properties of concrete or in an aggregate’s mineralogy, the researchers say. The observed improvements in mechanical properties such as compressive, flexural and tensile strengths, modulus of elasticity and drying shrinkage can ameliorate longitudinal and transverse cracking, corner breaks, punchouts and D-cracking, they write.

Improving Traffic Safety

Nanotechnology also has a role in improving transportation safety, according to Satish V. Ukkusuri, Ph.D., assistant professor, and Gitakrishnan Ramadurai, graduate student, Rensselaer Polytechnic Institute, in their 2009 TRB paper, A Comprehensive Review of Emerging Technologies for Congestion Reduction and Safety.

Looking ahead 20 years, the researchers identified future technologies, and focused on nanotechnology, as well as other emerging fields. “Nanosensors have potential to track bioterror agents, stress in materials and detect polluting agents in the atmosphere and tailpipes,” they say. “Nanosensors could be used in transportation to monitor pavement conditions, bridge conditions, pollution deduction, bioterror agent detection and air-quality monitoring.”

The feasibility of “cyberliths,” or “smart aggregates,” as wireless sensors embedded in concrete or soil is being studied. Researchers at Johns Hopkins University’s Applied Physics Laboratory have developed a robust wireless-embedded sensor, suitable for long-term field monitoring of corrosion in rebar, particularly in bridge decks, they say.

“Nanomaterials that are of interest in transportation include carbon fibers that are 100 times stronger than steel, nanocoating of metallic surfaces to prevent corrosion, and nano reinforcements in vehicle bodies, pavements and other transportation infrastructure,” Ukkusuri and Ramadurai write. “Automatic healing materials have potential to be used in guardrails that heal themselves, or concrete or asphalt that heal their own cracking.”

Road Science Tutorial

Nanotechnology Will Transform Infrastructure Will Impact Materials, Monitoring, Maintenance, Safety and Durability

Pavement preservation expert Larry Galehouse talks about tools and strategies that make sense for surviving the Great Recession

By Kirk Landers

“In times like these, the pavement manager’s most basic strategy is to keep sound pavements sound and keep bad pavements from becoming unsafe or unusable.”

So spoke Larry Galehouse, director of the National Center for Pavement Preservation, in an interview with Better Roads.

Indeed, Galehouse, one of the nation’s foremost experts on pavement preservation, sees the diminished road budgets of the Great Recession as a litmus test for pavement management strategies.

“The agencies that have pursued the traditional ‘worst first’ strategy, giving priority to rebuilding bad pavements, are feeling the budget shortfalls most acutely,” he notes. “Agencies that have given priority to prevention — to keep good pavements in good condition — are in much better shape.”

And that homily is Galehouse’s advice to pavement managers dealing with severely constrained budgets. “It costs a lot less to extend pavement life while the pavement is healthy than it does to rehabilitate or rebuild a pavement that has deteriorated too far,” he observes.

The key to executing a pavement preservation strategy is to bring the right prevention tool to the right pavement at the right time, he says. The challenge is to select the treatment with the greatest benefit for that particular pavement, and Galehouse notes that it takes a lot of up-front work to make that diagnosis.

“For example,” says Galehouse, “you need to identify subsurface failure spots, dig them out and repair them before applying a surface treatment.”

And Galehouse stresses that pavement preservation priorities apply to concrete and asphalt pavements alike.

Asphalt Interventions

One of the least-expensive asphalt pavement treatments that Galehouse often recommends today is the use of a rejuvenator shortly after the surface course is laid. A true rejuvenation of an asphalt surface requires the introduction of maltene fractions. Thus, rejuvenators containing maltenes – the oily, resinous component of asphalt – increase the asphalt binders’ resistance to oxidation by improving the chemistry and prolonging its flexibility.

Rejuvenator treatments can be repeated every few years to keep the surface pavement supple and weather-resistant, typically prolonging its life by two to three years. The maltene-based rejuvenator is clear and doesn’t affect paint lines.

“It’s important to get the true, maltene-based rejuvenator if a change in binder chemistry is desired,” says Galehouse, adding that there are many other products on the market. “I suggest getting references from other agencies about how the product worked on past projects,” he says.

Rejuvenators are often applied after a road pavement or airport landing strip has been retexturized, says Galehouse. “Today’s retexturizing technology is fast and inexpensive, and it improves pavement friction.”

The roughened surface accepts the rejuvenator treatment more efficiently and the process improves the tractive qualities of the aggregate. Galehouse warns that pavements with poor-quality aggregate will polish again relatively quickly, while good-quality aggregate will keep its texture for a long time.

Crack Treatments

As highway agencies have migrated to a prevention-first philosophy of road management, emphasis on crack treatment has grown. The process is inexpensive and has been shown to extend pavement life by two years and often more.

Galehouse considers crack treatment an important tool in the pavement manager’s toolbox.

“There are two approaches,” he says. “Crack sealing is a series of steps that first machines a reservoir in the crack, cleans the reservoir with compressed air, and then fills it with sealant. This approach can be very effective when used on the right pavement at the right time.” Galehouse estimates that crack sealing typically extends pavement life at least two to four years.

Crack filling, a process in which debris is blown out of the crack and the crack is filled with sealant, is used for nonworking cracks and wider cracks. Galehouse says crack filling typically adds about two years to the life of a pavement.

“Both of these processes are pothole preventers,” he says. “And the longer you can prevent potholes, the longer you can avoid more-expensive interventions like milling and overlays.”

Surface Treatments

Chip sealing has evolved as rapidly as any preservation technology over the past decade, says Galehouse, as contractors and suppliers have stepped up the quality of materials and application techniques. “It’s more of a science now,” says Galehouse, “though there are still people who don’t recognize it as such.”

Perhaps the most dramatic leap forward in chip sealing will be offered through the SHRP2 (Strategic Highway Research Project) Project R-26 in which chip seals with carefully selected aggregate and emulsion applied with precise construction technique and finished with a fog seal can be placed on high-volume roads. This will finally demonstrate that chip seals can perform excellently on high-volume roads when care is taken in design and construction, says Galehouse.

“A high-quality chip seal applied to a sound pavement prevents sunlight and water from destroying the pavement,” says Galehouse. “It also adds macro-texture to the road surface to enhance traction, and with a fog seal it provides more visibility to paint markings by improving contrast.”

Other surface treatment interventions include slurry sealing and microsurfacing. Slurry seals are a mixture of fine aggregate, emulsified asphalt, water and additives placed by special machines in a thin coat, one stone thick. The slurry seal fills hairline cracks and delays pavement oxidation, and is appropriate for urban/suburban neighborhood roads in good condition.

Microsurfacing is a slightly thicker intervention than the slurry seal, combining polymer-modified asphalt emulsion, crushed aggregate, water and other additives in a carefully specified mix design, and placed by specialized equipment. “Microsurfacing adds thickness to the pavement structure, so it can correct rutting and minor raveling, and improve friction,” says Galehouse. “It is also designed to stand up to high-traffic volumes and heavy loads.”

Overlays

The next stop on the prevention continuum for asphalt pavements is the ultra-thin overlay — typically, 3/4-inch thick or less. “This is an intervention for a sound pavement,” says Galehouse. “With the advances in mix design and placement practices, it has become a very effective tool. It protects the surface of the original asphalt, fills minor imperfections, and improves ride quality.”

Ultra-thin overlays can also be designed to deliver other benefits. Use of a rubberized asphalt binder, for example, can mitigate traffic noise with great effectiveness. An open-graded friction course design can reduce spray during rain and enhance the quality of runoff water.

Thin overlays — up to 1.5 inches in thickness — cost more, but by virtue of their thickness can smooth out deeper imperfections, and achieve greater smoothness that improves the ride quality of the pavement.

Milling is the tool when the surface pavement has deteriorated beyond the point where lesser interventions can restore its condition. Milling is also employed in metropolitan areas where a simple overlay will not align properly with gutters.

“This is the Cadillac fix in the prevention tool box,” says Galehouse. “You mill off a thickness of deteriorated pavement and overlay with new asphalt to restore the ride quality. It’s a lot cheaper than waiting until you have to do a total structural rehabilitation, but for stretching budget dollars, you want to work as far up the deterioration curve as possible.”

In-place recycling technologies can also be very effective in treating aging pavements, says Galehouse. “It’s important to make sure the project you have in mind is a good fit for the technology, whether it’s hot-in-place or cold-in-place,” says Galehouse. “The best procedure is to get a good, reputable contractor to evaluate the project in terms of its appropriateness for (either).”

When in-place recycling technologies are viable, they bring a cost advantage to the project as well as environmental advantages, such as less energy consumption, lower CO2 emissions, and a 100-percent recycling of the existing resource.

Concrete Pavement Interventions

Contractors and pavement managers have developed an elaborate toolbox for concrete pavement prevention, notes Galehouse.

Joint resealing lies at the low end of the cost spectrum, followed by diamond grinding and partial and full-depth repairs.

“Cost analysis is key, especially with the more-expensive interventions” says Galehouse. “You have to weigh the cost of repair against the cost of replacement. So, for example, if you had to replace every other panel on a stretch of road, it would probably make much more sense to just replace that stretch of road.”

In many cases, says Galehouse, concrete pavements just need diamond grinding to remove surface imperfections and improve smoothness. Over a period of time, concrete slabs can settle due to movement of the road’s subbase. Most of the imperfections occur where the panels abut.

“If you have vertical displacement – called faulting – of the slabs, you might consider retrofitting dowel bars to stabilize the joint and improve the transfer of loading between slabs,” says Galehouse. “If they are tied together, just diamond grind it and seal the joint.”

While some pavement managers aren’t convinced that joint sealing improves concrete pavement performance, Galehouse does advocate the practice.

“The important thing is to keep the incompressibles out of the joint,” he says. Incompressibles include foreign objects that can clog joints and prevent the slabs from flexing as temperatures change and cause the panels to expand and contract. “By keeping joints sealed, you keep out the material that can cause blow-ups,” says Galehouse. “Seals also help protect the pavement from water seeping into the base and creating a ‘pumping’ action that forms voids in the subbase and cause cracks and even breaks in the panel.”

Joint seals typically last 10 to 12 years before leaks appear, says Galehouse.

Does prevention pay off with concrete roads? “If we take good care of our concrete roads with the tools we have today,” says Galehouse, “they will last far beyond what we have come to expect — over 50 years for good concrete.”

Coping with Our Times

There are still pavement managers in America who give their worst pavements first priority in budgeting, Galehouse notes, and their systems are suffering the most from the diminished budgets of the Great Recession.

“In good times or bad, the strategy that makes the most sense is to first keep your good pavements good — your dollars go further and your system stays stronger,” says Galehouse. “Then you keep your marginal pavements from deteriorating any further — to minimize safety concerns and the cost of the ultimate repair. And then you rehabilitate bad pavements as dollars allow, starting with safety concerns.”

Galehouse concedes that today’s tight budgets constrict everyone, but those pursuing sound management strategies that stress prevention will outperform the others, he says.

“Agencies that follow an asset management approach will come out of this cycle in good shape,” he concludes.

Larry Galehouse

Larry Galehouse is a licensed professional engineer and a licensed professional surveyor. His experience includes tenure with an engineering consulting firm and with a large state DOT. In 2003, he helped found the National Center for Pavement Preservation located at Michigan State University in Lansing, Mich. Galehouse has been a leader in pavement preservation initiatives within AASHTO, NACE, FHWA and TRB. Contact and learn more about the National Center for Pavement Preservation at pavementpreservation.org.

Agencies looking for dollar value balanced with road quality are looking at concrete overlays

By Daniel C. Brown

This 8-inch unbonded, plain-jointed concrete overlay was placed on I-44 in 1999 in Webster County, Mo.

More than ever before, state departments of transportation (DOTs) and other roadbuilding agencies are choosing concrete overlays as a way to rehabilitate and preserve their existing pavements. Concrete overlays allow agencies to save the cost of removing an existing pavement. And significantly, concrete is generally more competitive these days with asphalt on a first-cost basis, as well as a lifecycle basis.

“Concrete overlays allow us to take the substantial equity that we have in our existing pavement system, which generations before us have invested in, and to hold onto that investment,” says Dale Harrington, P.E., principal senior engineer, Snyder & Associates, on behalf of the National Concrete Pavement Technology Center. “We can hold that investment by utilizing the strength of that existing pavement, be it in concrete or asphalt, and enhance it with a concrete overlay. That way, we bring the pavement into a whole new cycle without having to destroy the existing slab.

This bonded concrete overlay was placed 4 inches thick on asphalt and sawed into 4-foot-square panels. It’s on U.S. 60 in Neosho, Mo.

“The other major benefit of concrete overlays is sustainability,” says Harrington. “By leaving the existing pavement in place, and not wasting it, we are making the pavement even more sustainable. That is a huge plus!”

What’s more, concrete overlay technology has matured, which helps spur growth, says Leif Wathne, P.E., vice president of highways and federal affairs, American Concrete Pavement Association (ACPA). “In large parts of the country, there has been phenomenal growth over the past five years in concrete overlays,” says Wathne.

“Concrete overlays give states and other agencies an opportunity to seize a long-term solution,” says Gerald F. Voigt, P.E., ACPA president and CEO. “Most of the DOTs are operating under tight budgets these days, and we don’t have a new highway bill. A concrete overlay does not require an expenditure to tear out the existing pavement. Overlays are quite adaptable to a tighter budget scenario.”

Concrete overlays come in two primary categories: bonded and unbonded. The key difference is that with bonded overlays, the new structure depends on the underlying pavement – asphalt or concrete – to act in unison with the overlay. The new pavement is designed to count heavily on the strength of the underlying structure. Bonded overlays require that the existing pavement be in fair to good structural condition, and they are generally thinner than unbonded overlays.

Unbonded overlays treat the old pavement as a stable base for the new overlay. Unbonded concrete overlays, which are generally thicker than bonded overlays, are often placed to rehabilitate asphalt or concrete pavements that are in poor condition. Unbonded overlays do not require a bond between the new overlay and the existing pavement.

Both bonded and unbonded concrete overlays can be placed on three types of pavements: concrete, asphalt, or composite structures. Composite pavements are generally those where asphalt has been placed over concrete.

“The adoption of concrete overlays by DOTs has enabled them to introduce competition in a market segment where they traditionally have not seen much competition between the two industries,” says Wathne. “That competition enhances the ability of agencies to stretch their highway dollars.”

From 2004 to 2009, concrete overlays of 6 inches or less have grown from about 1.2 million square yards to about 5.4 million square yards, ACPA data shows. And according to bid-letting information, a total of 17 million square yards of overlays were built in 2009 and 2010 – and about half of that was composed of thinner overlays. “Most of it was built on existing asphalt pavement,” says Voigt. “So that is just a huge jump from what we have seen in the past.”

Wathne says that when you introduce the concrete pavement industry into the rehabilitation market segment, that not only lowers prices, it stimulates innovation. “You have another industry in there challenging the existing industry, and that is a good thing for the customer, which in this case is the DOT or the public sector, actually,” says Wathne.

In terms of innovation, ACPA’s Voigt points to a concrete overlay project happening this year on U.S. Highway 18 in Chickasaw and Fayette Counties in Iowa. There, contractor Manatt’s, of Brooklyn, Iowa, is building an unbonded overlay on 19 miles of two-lane roadway. This is the first such concrete overlay to be built one lane at a time, under traffic. Stringless concrete paving, by which automated machine controls guide the paver, opens up the project and allows concrete trucks access from the centerline side. A 24-hour pilot car will lead a group of vehicles first in one direction, then in the other.

The existing roadway is a 7-inch-thick concrete pavement topped by a 6-inch asphalt overlay. The asphalt overlay will be milled down by 1 to 1.5 inches, and a 4.5-inch concrete overlay will be applied, says Todd Hanson, P.E., a PCC engineer in the Materials Division of the Iowa DOT.

As evidence of the growth of concrete overlays, Voigt points to Kansas, where the DOT has recently let approximately 1.5 million square yards of concrete overlays for Interstate 70. “Those overlays are what we call a ‘6-by-6-by-6’ overlay – 6 inches thick and 6-foot-by-6-foot panels,” says Voigt.

“There is an upcoming national open house on that,” Voigt says. “It is essentially a mill-and-fill using concrete instead of asphalt. They are milling down and placing concrete to re-establish the grade that was there.”

In Missouri, MoDOT has built some 25 concrete overlay projects over the past 12 years, says John Donahue, P.E, construction and materials liaison engineer. Most of those projects have been built on Interstate highways, but some have been paved on lower-volume roads as well. Donahue says Missouri has placed several unbonded concrete overlays that use a geotextile as the bond breaker between the old concrete and the new.

“And we have done, to a lesser extent, a number of thin bonded concrete overlays,” says Donahue. “Typically those are about 4 inches thick. In that case, we actually try to get a bond with the asphalt below. We have typically used those at intersection locations where we have had historical rutting occurring on the asphalt.”

A third type of overlay in Missouri is what the state calls its “big block design.” It is an unbonded overlay – thinner than the state’s conventional concrete overlay, which is 8 inches thick. “We would construct it at 5 or 6 inches thick, and place it down on an asphalt surface, or even a concrete surface if we use the geotextile interlayer,” says Donahue. “Then we saw the pavement into 6-foot-by-6-foot panels.”

Technology transfer

ACPA and the National Concrete Pavement Technology Center (CP Tech Center) provide instructional information and provide training related to concrete overlays. ACPA’s education and training program, for example, focuses on delivering training on various aspects of design, construction and pavement rehabilitation using concrete overlays.

The CP Tech Center offers workshops to state agencies on concrete overlays through the National Concrete Consortium. The consortium is a group of 21 states that have pooled their resources and joined together to work on concrete pavement issues and solutions, Harrington says. This NC2 group meets annually to hear speakers and discuss concrete pavement issues.

The CP Tech Center, in partnership with the Federal Highway Administration (FHWA), also provides technical support to DOTs that are considering such overlays. “We have been providing technical experts to assist the DOTs with identifying suitable candidate pavements for the overlays, helping them with the specifications and assisting with construction support,” says Tom Cackler, P.E., director of the CP Tech Center.

Harrington, who works full time for the CP Tech Center and is its former director, says concrete overlay expert teams have visited 22 different sites across the nation over the past two-and-a-half years. An example comes from South Dakota, where the DOT requested an expert team’s services.

The project was constructed on South Dakota Route 50 in 2009. “It was an existing 8-inch concrete pavement with 10-inch shoulders,” says Harrington. “The South Dakota DOT placed an asphalt interlayer as a bond breaker, then a 7-inch unbonded concrete overlay.

“The Center’s team, including FHWA, completed a presentation on overlays to the South Dakota DOT and gave them a site evaluation field review of Highway 50. The team provided comments on design and specifications as they were being developed. Finally, the team provided guidance during the construction and sent the Center’s mobile laboratory to the project for a week. The lab completed testing of material properties for South Dakota DOT. The Center’s team assistance was provided at no cost. When the project was complete, we sent them a final report and evaluation.”

Harrington says when the expert team program concludes in mid-2012, the CP Tech Center will publish a report on all the sites that have been visited. FHWA has requested that the full report include lessons learned about concrete overlays during the expert team consultations. That full report will be shared with all state transportation departments, Harrington says. States visited to date include Delaware, Georgia, Illinois, Louisiana, New Mexico and Virginia. Others involved include Maryland, Minnesota, Nevada, North and South Dakota, Pennsylvania, Texas, Washington state and West Virginia.

“So far, four states have done the actual construction,” says Harrington. “Some of them, such as Virginia, are working on them right now. Virginia built one this year; the others will build projects as they get the funds to do so.”

In North Dakota, the state has completed two concrete-on-asphalt overlays, says Clayton Schumaker, an assistant materials engineer with the DOT. The most recent one was finished this summer – a 5-mile project on ND Highway 200 near Hillsboro. A portion of the existing pavement consisted of asphalt with an aggregate base, and the remainder was a composite pavement with a concrete base paved in 1948.

The roadway consists of several segments, so various overlay thicknesses were used – ranging from 5 to 7.5 inches – to account for the different existing pavements and varying traffic loadings. Two major industrial facilities bring heavy truck traffic on ND 200 in the project area – and both facilities requested concrete, based on its performance since 1948, Schumaker says.

“One consideration was cost, and our engineer’s estimate says the concrete overlay is less expensive than doing full-depth asphalt reclamation then placing an asphalt overlay,” Schumaker says. “We’re looking at concrete overlays for a number of other projects where we have high-traffic volumes and the rehabilitation strategies are limited to full-depth reclamation, total reconstruction or the concrete overlay.”

Technical summary

In addition to technical support from the expert teams, the CP Tech Center has published “A Technical Summary of the Design of Concrete Overlays Using Existing Methodologies,” dated May 2011. The document provides an overview of the concrete overlay design process and identifies some of the more sensitive variables inherent with three different software procedures: (1) the 1993 AASHTO Guide for Design of Pavement Structures; (2) the Mechanistic-Empirical Pavement Design Guide (MEPDG); and (3) the ACPA method for bonded concrete overlays on asphalt pavements (BCOA).

The first method, the 1993 AASHTO Guide, is the procedure most commonly used today for concrete overlay thickness design. The MEPDG, and more precisely, the recently released DARWin-ME program, is being implemented by numerous states. Finally, ACPA’s BCOA method is presented to address the unique behavior of thinner-bonded concrete on asphalt. The technical summary is expected to be released later this year.

As state transportation agencies and roadbuilders grapple with the persistent economic concerns, a growing number of them are increasingly turning to concrete overlays to provide high-quality, durable, sustainable and economically-viable solutions. For more information on concrete overlays, visit acpa.org.

Concrete APPS

ACPA Apps can do a lot of work for you

By Robert Rodden, P.E.

Director of Technical Service and Product Development

American Concrete Pavement Association

It is the era of technological wonders in communication. Consider, for example, how smartphones are becoming dominant features of the communication landscape.

Keeping pace with this important technology wave, the American Concrete Pavement Association (ACPA) introduced its first web-based applications last November, and has since introduced more than 40 web-based tools, or web applications, via a special web portal, http://www.apps.acpa.org. ACPA has released new iPhone and iPad applications.

The web apps are divided into several categories including some general interest apps, design apps, and construction and pavement analysis tools, as well as interfaces to design software. Although these apps are germane to concrete pavement placement, repair or preservation, many of these web-based tools are more general and will help people with broader construction interests.

One very popular web app is ACPA’s National Concrete Overlays Explorer at http://www.apps.acpa.org/apps/OverlayPass.html. The exploration begins with a map featuring push pins, and adjacent to it, a sidebar menu of project details that serve as filters. By activating a push pin or selecting from the sidebar menu, the user can view project construction details, photos, performance information and much more. The app is designed to answer questions agencies, consultants and contractors have about key project details, for example where concrete overlays have been used and how they have performed.

The general-interest apps include a database of state agency practices, a glossary of concrete pavement industry and general transportation-construction terms, a units converter with many industry-specific conversions not included in other online converters, and other useful tools that can benefit construction professionals on the grade or in the office.

Design apps include a bonded concrete overlay on asphalt thickness designer. Developed by ACPA with support of the Federal Highway Administration (FHWA), the National Concrete Pavement Technology Center (CP Tech Center) and the Illinois Center for Transportation (ICT) at the University of Illinois at Urbana-Champaign (UIUC), this application is based primarily on the results of FHWA-ICT-08-016, “Design and Concrete Material Requirements for Ultra-Thin Whitetopping.” This is the formal name of a research project conducted in cooperation with the ICT, the Illinois Department of Transportation (IDOT) and FHWA.

The online thickness designer allows pavement design professionals or others with engineering expertise to enter general design factors, existing pavement structure details, concrete material details and factors related to the concrete overlay to determine the necessary bonded concrete overlay thickness.

Among the 18 design apps are a Westergaard stress and deflection solver, a compression seal joint width calculator and an online thickness designer based on ACPA’s popular StreetPave software for conventional jointed plain concrete pavements. Also included is an online k-value calculator, as well as an equivalent single axle load (ESAL) calculator that allows users to estimate future or historic traffic counts.

Construction and pavement analysis tools include an extremely popular evaporation rate calculator; a strength converter that converts between compressive, flexural, split tensile strengths and modulus of elasticity; a pavement joint noise calculator, and a concrete temperature calculator. Users also can find highway specifications used in airport pavement applications, calculate area and volume, determine staking intervals and the maximum recommended joint spacing, and perform more than a dozen different construction and pavement analysis operations using ACPA’s web apps.

In the pavement design software section, there are interfaces to evaluation versions of ACPA’s StreetPave roadway pavement design tool, WinPAS roadway pavement thickness design and evaluation tool (based on the 1993 AASHTO Design Guide for Pavement Structures), AirPave airport pavement design tool, and the newest design tool in ACPA’s software suite, PerviousPave, a pervious concrete pavement design tool. The pavement design software section also includes links to:

• COMPASS: computer-based guidelines for job-specific optimization of paving concrete. This tool is currently under review by the FHWA and is not an official set of guidelines, yet. When accepted by FHWA, it will result in a truly performance-driven mixture design system.

• HIPERPAV III (HIgh PERformance Concrete PAVing) software, developed by the Transtec Group for the FHWA, and used to analyze the early age behavior of jointed concrete pavements continuously reinforced concrete pavements and bonded concrete overlays.

• EverFE 2.24, a 3-D finite-element analysis tool used for simulating the response of jointed plain concrete pavement (JPCP) systems to axle loads and environmental effects. EverFE was jointly developed by the Universities of Maine and Washington with funding from the Washington and California State Departments of Transportation.

• And DowelCAD 2.0, a software program created collaboratively for optimization of dowel bar design. The software also allows engineers to determine joint responses to varying dowel sizes or investigate the impact of various alternate dowel bar configurations and shapes.

Moving Ahead

Keeping pace with web-based technology also means meeting the growing demand among smartphone users. ACPA has developed a number of iPhone and iPad apps, and continues to monitor use of other platforms, including Android, with an eye on further development to meet demand. The current list of ACPA’s iPhone and iPad apps includes:

Area and Volume Calculator: An app that allows users to quickly calculate plan area and volume of material based on a pavement or subbase/subgrade layer’s thickness, width and length.

Evaporation Rate Calculator: This app uses the evaporation rate equations in Paul Uno’s ACI Materials Journal article, “Plastic Shrinkage Cracking and Evaporation Formulas,” (July/August 1998). The equations are based on the popular evaporation rate nomograph from ACI 305R, Weather Concreting. Using this tool, users can quickly calculate the evaporation rate at hourly intervals based on concrete temperature, air temperature, ambient relative humidity and wind velocity.

Concrete Mixture Proportioner: Provides a method of proportioning a concrete mixture using the absolute volume method in substantial conformance with ACI 211.1-91, “Standard Practice for Selecting Proportions for Normal, Heavyweight and Mass Concrete.”

Maximum Joint Space Calculator: Allows users to calculate joint spacing in jointed plain (unreinforced) concrete pavement.

Staking Interval Calculator: Calculates the rate of change of a vertical curve and, based on this value, provides maximum staking interval recommendations.

Subgrade Resilient Modulus Calculator: Based on the conversion factors included in NCHRP Report 128, “Evaluation of AASHTO Interim Guide for the Design of Pavement Structures,” this tool allows users to quickly estimate the Subgrade Resilient Modulus (MRSG) from either a California Bearing Ration (CBR) or Resistance Value (R-value) measurement.

Joint Noise Estimator: An app based on the work of acoustics expert Dr. Paul Donavan, Sc.D., a senior scientist at Illingworth and Rodkin. This tool allows designers to estimate the impact of various joint geometries and condition on the overall tire-pavement noise level. It may also be used to guide pavement maintenance efforts in terms of the noise-related benefits attainable from sealing joints.

These mobile applications are available in Apple’s iTunes App Store store (http://www.store.apple.com/) for a nominal fee. Users of iPhones and iPads who click on the iTunes App Store link on the ACPA App Library site will be taken directly to an application purchase site; all other users will be directed to landing pages that describe the product and include ordering information.

For additional information about the ACPA web apps and links to software programs, contact the author at 847.423.8706 or rrodden@acpa.org. v

No Gas Tax Hike

No Problem?

The Association of Equipment Manufacturers (AEM) has proposed a revenue-neutral solution to rebuild and modernize America’s Interstates.

A multi-year highway bill can be fully funded without raising the gas tax, says AEM.

The plan is straightforward enough: It’s a user fee. But Congress will almost certainly balk, because since SAFETEA-LU ran out, any suggestions that road users pay more has been stonewalled.

“With no political will by policymakers to increase the gas tax, we must look for other practical solutions that ensure the nation’s transportation needs are satisfied,” says AEM President Dennis Slater.

This proposal will provide critically needed funding, “without raising motor fuel or diesel fuel taxes and with no increase to the debt or the deficit,” says the plan’s architect, Jack Schenendorf, former vice chairman of the National Surface Transportation Policy and Revenue Study Commission, a major analyst body optimistically assembled before SAFETEA-LU expired in 2009.

The AEM proposal will inevitably run head-on into an unwillingness to use tolls, or user fees paid as if they were tolls, held by both the administration and the Republicans on the House Transportation and Infrastructure Committee – and a lot of others in Congress. The core of their opposition is that the roads were built with tax dollars and taxing the taxpayers to use them is an unfair double tax (tolling new roads is acceptable to both sides, but without an adequate Highway Trust Fund its unlikely many of those will be built in the short term). And Congress will worry mightily about privacy issues.

On the other hand, the proposal would do what no one else has been able to do without a gas tax hike – fund an adequate Highway Trust Fund (HTF) for the next five years. Alternatives to a higher gas tax have been tossed around since SAFETEA-LU expired and all through the extensions that have kept it comatose since, but none offer rapid income; they are nearly all long-term ideas with no reliable timetable.

The revenue-neutral transportation funding proposal offers two fee solutions:

A Federal Interstate User Fee

All vehicles using the Interstate Highway System would pay a user fee. The fee would be collected through an “EZ Pass”-like system, which would be entirely electronic. There would be no tollbooths.

All of the revenues generated by the fee would be deposited in a special account in the Highway Trust Fund. The revenues would be used exclusively to restore the Interstate Highway System to a state of good repair and to expand and modernize it to meet the challenges of the 21st century.

The fee structure would be set annually, by an independent group of experts, at the level necessary to reimburse the states in accordance with policies established by Congress for the federal share of these improvements. No higher, no lower. The fees would not be designed to control the level of traffic or to “price out” drivers from using the Interstate.

A Federal Motor Carrier User Fee

This fee would be imposed on commercial trucks’ usage of all roads and would be collected through GPS-like systems currently being used by many trucking companies.

Trucks would not be double-charged for miles traveled on the Interstate; rather, those miles would be recorded through the Federal Interstate User Fee program.

SAY WHAT?

“The credit, the saving, and convenience of this country all require that our great roads leading from one public place to another should be straightened and established by law … To me these things seem indispensably necessary.”

– General George Washington, 1785, realizing America’s core need to build and care for a superior road system

Fed Grants Boost State DOT Budgets

Washington has handed out $417.3 million in grants for state highway projects – seriously less than the $13 billion states had asked for in their wish lists.

Secretary of Transportation Ray LaHood says the grants will fund work ranging from Interstate maintenance to research into innovative bridge materials and construction methods.

“The demand from the states for these funds shows just how critical the need is for infrastructure investment,” he says. The Federal Highway Administration (FHWA) invited states to apply in June for federal funding from 14 discretionary grant programs and received more than 1,800 applications, totaling nearly $13 billion, which is more than 30 times the funds available.

“The list of state highway projects in need of financial help grows almost daily,” says FHWA Administrator Victor Mendez. “At a time when states are facing serious budgetary constraints, these grants will help fill a critical need. Investments like these are immediate and long-lasting and will help create jobs.”

And what did your state get? See the state-by-state list at fhwa.dot.gov/pressroom/fhwa1137/

And the Awards Go To….

The American Society of Business Publication Editors (ASBPE) has honored Randall-Reilly Publishing Co., parent company of Better Roads, with three national editorial awards, 12 regional editorial awards and three design awards in the organization’s Azbee Awards of Excellence.

This is a peer-judged contest that honors the top Business-to-Business publications.

Better Roads won four awards — two gold, one silver and one bronze.

Mud Dud

EPA has got a little mud on its tires.

The U.S. Environmental Protection Agency has decided to back off from proposed “numeric turbidity limits” on the amount of dirt the agency will allow in stormwater from construction sites.

We might call dirt in water plain ol’ mud.

The chief executive officer of the Associated General Contractors of America (AGC), Stephen E. Sandherr, reacted by saying that, “The fact that the EPA recognizes the serious flaws in the data supporting its efforts to impose a rigid, one-size-fits all, limit on the amount of dirt in rainwater leaving construction sites is encouraging. Indeed, contractors are already required to take significant measures to ensure that dirt – clean, uncontaminated dirt – does not escape from project sites. Setting a specific limit on how much dirt should be in rainwater will only force contractors to spend billions more on new dirt-busting measures that may not work, expose firms to costly lawsuits from outside groups and put them at risk of receiving tens of thousands in daily fines.”

But Sandherr is not entirely happy with the agency’s withdrawal, because he notes, “EPA is only seeking to delay imposing its new mud rule, instead of abandoning the idea all together.”

Technically, the EPA has withdrawn its 2009 proposal from the White House Office of Management and Budget. OMB clearance is the last step in the rulemaking process before a proposal (or final rule) is signed and published in the Federal Register.

The Fall Goes On

New infrastructure rankings in the World Economic Forum’s 2011-2012 Global Competitive Report are due out this month. According to a copy obtained by Reuters news agency, the U.S. ranks 16th, falling a notch as South Korea moved past us in the last twelve months.

In the forum’s 2007-2008 report, American infrastructure was ranked 6th best in the world. Take a look at the 2010-11 rankings:

WORLD INFRASTRUCTURE RANKING

1. HONG KONG

2. GERMANY

3. UNITED ARAB EMIRATES

4. FRANCE

5. SINGAPORE

6. SWITZERLAND

7. NETHERLANDS

8. UNITED KINGDOM

9. CANADA

10. SWEDEN

11. JAPAN

12. ICELAND

13. DENMARK

14. SPAIN

15. UNITED STATES

Source: World Economic Forum, “The Global Competitiveness Report 2010-11,” Table 6.

Thin Open-Graded Surfacings Drive Market

By Tom Kuennen, Contributing Editor

Now, more than ever, thin open-graded friction courses (OGFCs) are driving the market for drainable, high-friction, noise-attenuating asphalt mixes.

A thin crumb, rubber-modified, open-graded wearing course is placed on California Highway 1 near Fort Bragg; the mix incorporated a warm-mix additive to ensure workability, following the two-hour drive to the Pacific Coast from the plant.

This new generation of OGFCs is being bolstered by the advent of high-performance “spray” pavers that place thin, polymer-modified OGFCs quickly and with great consistency, and by new materials that halt the potential “draindown” of liquid asphalt within an open-graded mix.

The use of these new OGFCs also is expanding as a result of the general trend toward pavement preservation, as cash-strapped road agencies realize that it’s a lot cheaper to extend pavement life by spending limited funds on preservation techniques at the right time, rather than allow a road to deteriorate to the point of failure, with costly reconstruction the only option.

A conventional OGFC is a layer of asphalt that incorporates a skeleton of uniform aggregate size with a minimum of fines. It features an open aggregate structure in which larger-sized aggregate is held in place by polymer-modified and fiber-modified Superpave performance-graded liquid asphalts. Most OGFCs are 3/4-inch thick, and never thicker than 2 inches.

The OGFC’s open structure of 15 percent or more voids allows water to drain right through the driving or friction course to an impervious intermediate course below, and out into roadside ditches. The result is the near-complete elimination of tire spray and hydroplaning, making a safer pavement and saving lives. It also results in a quieter pavement as noise is attenuated within the gaps between the aggregate. OGFCs should be elevated above the shoulder, as the water drains onto the shoulder and hence to a roadside ditch.

A Variety of Names

Today’s spray-applied OGFCs are known by a variety of names. Oklahoma DOT has expanded the use of what it calls spray-applied ultra-thin bonded wearing courses. In Nevada, they’re known as ultra-thin asphalt concrete surfacings (UTACS, pronounced “you-tacks”), which are gap-graded wearing courses, bonded to the surface by a warm polymer-modified membrane, followed immediately by the hot, gap-graded, ultra-thin asphalt concrete friction layer.

UTACS are similar to Caltrans’ bonded wearing course, “a gap- or open-graded, ultra-thin hot-mix asphalt mixture applied over a thick polymer-modified asphalt emulsion membrane,” to quote the agency. “The emulsion membrane seals the existing surface and produces high binder content at the interface of the existing roadway surface and the gap- or open-graded mix, all in one pass.” Recently, Caltrans has been increasing its use of crumb rubber-modified emulsion for these OGFCs in lieu of polymer modifier.

Such bonded wearing courses are primarily used in high-traffic areas as a surface treatment over hot-mix asphalt or Portland cement concrete pavements. They are placed over structurally-sound pavements as a maintenance treatment, but may also be used in new construction and rehabilitation projects as the final wearing course.

In a bonded-wearing course such as those specified by Caltrans, a polymer-modified asphalt emulsion membrane seals the existing pavement while bonding the gap-graded or open-graded mix to the surface. The thicker nature of the membrane allows it to wick upwards into the mix, filling voids in the aggregate and creating an interlayer of high cohesion that does not delaminate or bleed, if applied correctly.

A predecessor of today’s thin, open-graded wearing course designs is NovaChip, an ultra-thin, bonded, gap-graded wearing course placed by a specialized paver in one pass. This exclusive pavement process applies an ultra-thin hot-mix wearing course over a polymer-rich asphalt emulsion. The process rapidly secures the lift to the existing surface and allows for minimal traffic delays. Originally developed by a French contractor, the patent for NovaChip is currently owned by Colas S.A. and is licensed for use in the United States by Road Science LLC of Tulsa.

But what’s not happening today is an increase in deeper-lift OGFCs. While most states that use them place OGFCs as thin asphalt lifts at 3/4-inch depth or less, the Oregon DOT has been placing 3/4-inch open-graded mixes in structural layers of 2 inches or more for about 30 years, reports Dr. Steve Muench, et. al., at the University of Washington-Seattle, in a June 2011 report for the Oregon DOT. He adds the Washington State DOT has used similar mixes since the early 1990s, although more sparingly. Due in part to the damage done to OGFCs by studded tires used in Oregon, the report recommends that use of 3/4-inch OGFCs be discontinued in the state (see below).

OGFCs for Cold Weather?

Typically, OGFCs tend to be confined to states without severe winters, as it’s perceived that water trapped within the drainable layer can expand and cause the open-graded layer to ravel, or create dangerous icing, leading to accidents.

One cold weather state, Wisconsin, recently looked at OGFCs as used and discontinued by northern-tier states and provinces, and received a recommendation that it not proceed.

“OGFC has historically not been used in Wisconsin due to concerns about its performance in a climate with a large number of freeze-thaw cycles,” says Richard E. Root, P.E., Root Pavement Technology, in his 2009 Wisconsin Highway Research Program report, Investigation of the use of Open-Graded Friction Courses in Wisconsin. “Questions also exist about the cost/benefit of these mixtures.”

The study’s primary objectives were to determine if the OGFC mixture could be successfully used in the Wisconsin climate. After a literature review that listed many northern-tier states that had started “new generation” OGFCs, but had since discontinued them, Root concluded that Wisconsin should avoid them.

“While the use of OGFC mixtures in warm southern climates has been successful, this pavement has not proven to have the same successes in the northern freeze/thaw environment,” Root says. “None of the states or Canadian provinces with climates that duplicate Wisconsin’s use OGFC mixtures. On a routine basis, it is recommended that Wisconsin should not currently build pavements with an OGFC surface.”

This summer, Oregon had reason to abandon OGFCs altogether. In June, a technical report – Open-Graded Wearing Courses in the Pacific Northwest: Final Report by Stephen T. Muench, Ph.D.; Craig Weiland; Joshua Hatfield and Logan K. Wallace of the Department of Civil and Environmental Engineering, University of Washington – suggested that use of the 3/4-inch open-graded hot-mix asphalt (previously referred to as “F-Mix”) be curtailed.

“The best estimated service life of [Oregon] DOT 3/4-inch open-graded HMA ranges from 14 years (< 5,000 ADT) down to seven years (> 100,000 ADT), which is less than comparable dense-graded mixes,” Muench and researchers wrote in June. “The primary mode of distress is raveling and studded tire wear. Reduced service life, along with uncertain and unquantified safety benefits and a possible greater risk of early failure lead to a recommendation to discontinue use of 3/4-inch open-graded HMA in Oregon as a standard surface mix.”

Open-graded wearing courses used elsewhere in this country are not likely suited for use by Oregon DOT, due to their susceptibility to studded tire wear, they say, and the writers don’t recommend their adoption. “If 3/4-inch open-graded HMA does continue in use,” the writers say, “recommendations are [to] quantify its benefits, restrict its use to low-traffic routes (< 30,000 ADT), recalibrate the state’s pavement management system’s expected life to be more in line with observed historical life, and require the use of a windrow pick-up machine or end-dump transfer machine when paving OGFCs.”

Download the new research at http://ntl.bts.gov/lib/41000/41300/41329/SPR680.pdf

Binder Modification Key

Open-graded friction courses have been used since 1950 in the United States to improve the frictional resistance of asphalt pavements, promote drainage of water from pavement and thus reduce tire spray, and reduce noise from the tire/pavement interface.

Spaces within the “open-graded” or “gap-graded” mix — and amounting to as much as 20 percent of the mix or more in some European mixes — help drain water and attenuate tire noise.

OGFCs are attaining a new popularity as states take a look at refined mix designs incorporating additives like polymer modifiers, rubber asphalt, fibers and hydrated lime. But it wasn’t always this way.

Prithvi S. “Ken” Kandhal and Rajib B. Mallick of the National Center for Asphalt Technology (NCAT) at Auburn University published a 1998 survey, Open-Graded Asphalt Friction Course: State of the Practice. The survey showed that, when these pavements were introduced in the 1950s, some states had problems with them. Improvements in OGFCs have made a vast difference. “These improvements have been achieved with the help of good design and construction practices,” they write.

The secret is modification of the asphalt binder. “A vast majority of agencies report good experience using modified asphalt binders,” Kandhal and Mallick say.

Georgia’s experience reflects the OGFC survey. “Early mixes used were very susceptible to premature failure due to weathering,” state Georgia DOT researchers in the DOT’s Progress in Open-Graded Friction Course Development, presented at the Transportation Research Board annual meeting in 1998.

Because of early problems, Georgia put a moratorium on OGFCs in 1982. Likewise, Washington State DOT tried smaller stone-sized (3/8-inch) mixes as thin (0.15-foot) wearing courses in the 1980s and early 1990s, but discontinued their use because of excessive studded tire wear problems.

Porous asphalt pavement is similar to open-graded friction courses (OGFC) but is meant for static loads and environmentally-sustainable stormwater drainage. A mix for the parade ground at U.S. Marine Corps Recruit Depot at Parris Island, S.C., contained Evotherm warm-mix additive instead of fibers.

But in the 1990s, Georgia developed a mix that incorporates a high degree of single-sized coarse aggregate, polymer-modified asphalt binder, stabilizing fibers and hydrated lime.

“This mix has been used extensively statewide since 1993,” the DOT reports. Now Georgia, pleased with its success, is urging other state DOTs to reassess OGFCs. “[Agencies] should reconsider the possibility of using this modified OGFC on high-volume-traffic facilities,” they say. “It is now Georgia DOT policy to use modified OGFC as the final ride surface on all Interstates and on state route projects that have daily traffic volumes exceeding 20,000 and are not in a reduced speed zone area.”

Modified vs. Standard Binders

After Georgia, use of polymer-modified — and more recently, rubber-modified — binders for OGFCs has become common. But the use of polymer or crumb rubber modifiers in OGFC binder may come at a cost: the ability of the pavement to drain water, at least in 4.75-mm nominal maximum aggregate size (NMAS) mixes.

That’s what Qing Lu, assistant professor, Department of Civil and Environmental Engineering, University of South Florida, and John T. Harvey, professor, Department of Civil and Environmental Engineering, University of California-Davis, say in their 2011 Transportation Research Board paper, Laboratory Evaluation of Open-Graded Asphalt Mixes with Small Aggregates and Various Binders and Additives.

Their paper is part of ongoing research to develop alternative asphalt surface mixtures that are quieter and durable without much sacrifice of safety, they say.

Five binder types (PG 64-16, PG 58-34PM, PG 76-22PM, asphalt rubber and PG 76-22TR) and two additives (hydrated lime and cellulose fiber) were selected for a 4.75-mm NMAS gradation, they write. A series of laboratory tests were conducted to evaluate their pavement surface performance-related properties, including acoustic absorption, texture, resistance to raveling, moisture sensitivity, permeability, friction, resistance to permanent deformation and resistance to reflective cracking.

“Results show that using polymer-modified or rubberized binders instead of unmodified binder in the 4.75-mm NMAS open-graded mixture reduces permeability,” they write, “but increases acoustic absorption, with the mixture containing asphalt rubber binder showing the most acoustic absorption improvement.”

Using asphalt rubber also can enhance the mix’s resistance to moisture damage or premature failure, raveling, rutting and potential resistance to reflective cracking. “There are also preliminary indications of friction improvement by replacement of conventional binder with asphalt rubber binder in the small-size aggregate open-graded asphalt mix,” Lu and Harvey say.

Rubber-Modified OGFC Binders

Rubber-modified binders for OGFCs now are seen on the west coast (California) and the east coast (South Carolina), as well as in the epicenter in Arizona.

On Napa Valley’s Silverado Trail, a specialized paver places tack coat at the rate of 0.17 to 0.20 gallons per square yard in advance of rubber-modified open-graded friction course.

Modified asphalt cement binder is required in OGFCs to prevent draindown of the binder and achieve the necessary level of adhesion and mix stability, reports the Asphalt Rubber Technology Service (ARTS) at Clemson University. “Although typically a polymer is used as the modifying additive to the asphalt cement binder, crumb rubber made from scrap tires may also be used as an alternative modifier,” according to the university.

The South Carolina rubber-modified open-graded friction course is placed 3/4- to 1-inch deep, with a crumb rubber content of 12 percent by weight of the liquid asphalt, or 0.85 percent by weight of the mix.

There, OGFC can be placed on either asphalt or concrete pavements, and it consists of roughly 93-percent crushed stone, 7-percent modified asphalt binder and a small amount of stabilizing fibers, Clemson’s ARTS says.

A next-generation polymer-modified open-graded friction course is placed on a Clark County, Nev., street.

“Rubber-modified open-graded friction course has all the same advantages as polymer-modified OGFC,” ARTS says. “Compared to concrete and standard asphalt dense-graded pavements, it has significantly lower noise levels, it has less surface water in wet weather, and it is generally safer in wet weather due to the better visibility and decreased hydroplaning, resulting from the lack of surface water on the pavement surface.”

In addition to sharing all the advantages of OGFC with its polymer-modified counterpart, rubber-modified OGFC also costs slightly less than conventional polymer-modified OGFC, ARTS says, adding when used in OGFC, scrap tires can be used at a rate of approximately 1,000 tires per mile of two-lane pavement.

Fighting Draindown with Fibers

While modifiers will help keep liquid asphalt binder from moving within an open-graded mix, it still may puddle at the bottom of a haul truck, or settle lower in the lift of mix just placed. This “draindown” of asphalt seriously compromises the durability of OGFCs.

The problem of draindown of liquid asphalt is solved by use of fibers – typically cellulose, but also mineral filler – which are used to hold the binder in place.

Tack coat eliminated: Movable bars spray polymer-modified emulsion tack coat in advance of thin-lift open-graded UTACS friction course in Clark County, Nev.

While cellulose fibers are most often used, new research indicates that polyethylene fibers may do the same thing in OGFCs. In the technical paper Characterization of OGFC Mixtures Containing Reclaimed Polyethylene Fibers written by V.S. Punith, of the Asphalt Rubber Technology Service at Clemson University, and A. Veeraragavan, Department of Civil Engineering, Indian Institute of Technology, Madras, and published last year in the Journal of Materials in Civil Engineering, it was reported that polyethylene fibers derived from recycled low-density polyethylene (LDPE) tote bags performed in OGFC mixes.

Polyethylene fibers recycled from LDPE bags collected from domestic waste improved OGFC mixes without fibers, they say. “Draindown test results indicated that OGFC mixtures with polyethylene fibers can be effectively used to retard draindown of the binder and mineral filler,” they write. “[T]est results indicated that OGFC mixtures with reclaimed PE fibers showed improvement in tensile strength and improved resistance to permanent deformation, fatigue-induced damage, and moisture susceptibility, when compared with mixtures without fibers.”

Draindown in Porous Mixes

While porous asphalt pavements are open-graded to encourage water drainage, they differ from open-graded friction or wearing courses by structure and function. Yet, they pose many of the same challenges as OGFCs, including binder draindown.

Porous asphalt pavement is an environmentally-sustainable infrastructure design that helps property owners manage stormwater effectively and inexpensively. They are specified for static traffic areas such as parking lots, and aren’t suitable for wearing courses.

Typically, a porous asphalt pavement will be composed of, from the bottom, an uncompacted soil subgrade that will optimize infiltration of water into the aquifer; a geotextile fabric that will permit water to pass but preclude movement of fines up into the structure; a stone recharge bed with same-sized aggregate and 40 percent voids; an optional stabilizing or “choker” course of single-size crushed stone smaller than that in the recharge bed; and an open-graded asphalt surface with 20-percent voids that permit stormwater to flow through the pavement into the stone recharge bed.

While OGFCs shoot for voids of 15 percent to control spray and noise, porous asphalt pavements let water drain directly into a recharge layer below, and the air-void target is 20 percent. The porous asphalt “green grinder,” or parade ground, constructed at the U.S. Marine Corps Recruit Depot at Parris Island, S.C., in May 2011 was not intended to reduce spray, hydroplaning or noise, but simply to provide the most efficient means of draining water from the paved surface and into the soil, while avoiding conventional detention ponds.

While fibers conventionally are used to stabilize porous asphalt mixes, an innovative warm-mix asphalt design for Parris Island saved money by eliminating fibers required for stability of the open-graded mix. The porous asphalt design also eliminated the expense of creating a detention pond and associated environmental requirements.

The elimination of fibers from the Parris Island mix was achieved by use of a warm-mix asphalt additive, Evotherm 3G from MWV Asphalt Innovations, which adds lubricity to individual microscopic asphalt particles, permitting production of asphalt at significantly lower temperatures than conventional mixes.

Evotherm stops the draindown of liquid asphalt by virtue of the lower mixing temperature it enables. “We were able to make the mix at 285 degrees F, instead of 350 degrees, which completely eliminates the problem of draindown,” says Dean Frailey, business development manager, MWV Asphalt Innovations. The mix was emerging from the truck at approximately 275 degrees and from the screed at about 245 degrees. No liquid asphalt was visible in the truck bed as mix was fed to a material transfer vehicle ahead of the paver.

CRM Binder in California

Crumb rubber-modified binder was used recently for an ultra-thin, open-graded wearing course in California’s Napa Valley. In the town of Napa, a 10-year-old asphalt overlay on the Silverado Trail was showing signs of wear over a 2.9-mile section. There was minor cracking, some raveling and a few areas required full-depth asphalt patching. But for the most part, the road was in good shape; it was structurally sound.

To preserve the road and extend its life, Caltrans turned to an ultra-thin bonded wearing course. In this process, a Roadtec SP-200 paver sprays a tack coat down just in front of the spreading augers, and the screed levels off a 3/4- to 1-inch-thick layer of open-graded hot mix.

On California Highway 50 between Placerville and South Lake Tahoe, an ultra-thin bonded wearing course lasted seven years, says Brian D. Toepfer, maintenance engineer, Caltrans. “I think it [performs] better than a mill-and-fill, and it is a lot less expensive.”

On the Silverado Trail, the Construction Division of Telfer Oil, Martinez, Calif., used the specially-equipped paver to spray down a heavily polymer-modified emulsion at a rate of 0.17 to 0.20 gallons per square yard. “The emulsion is similar to a PMCRS-2H emulsion, which is a standard chip sealing emulsion,” says Karl Meyers, general manager of Telfer’s Construction Division.

The paver immediately followed the emulsion with a 7/8-inch-thick layer of open-graded hot mix made with PG 64-16 liquid asphalt that was modified with crumb rubber. The target value for binder content was 8.5 percent, and the top-size aggregate in the mix was 3/8 inch. It also contained a small amount of sand.

Static compaction with two double-drum rollers followed the paver. “You have to run two rollers because you need to hit the temperature range on compaction, which is 180 to 280 degrees,” Meyers says. “That thin lift behind the screed is cooling fast, and you want to release the road to traffic quickly. Plus, the paver is moving at 70 to 100 feet per minute, so you need to run two rollers behind.”

The process has a number of advantages, Meyers says. “You are not getting any tack coat dragged around the city, you get an outstanding bond with the hot mix, you are forming a waterproof membrane, there is no water splash, and you can release the road quickly to traffic,” he says.

Polymer-Modified UTACS

In the meantime, a specialized paver has given a Las Vegas asphalt contractor entry into the growing market of ultra-thin asphalt concrete surfacings in Nevada and throughout the Southwest.

However, to correctly place UTACS or other bonded wearing courses, the right kind of paver is needed: One that has the ability to spray asphalt emulsion onto a pavement, and then immediately place a thin overlay on top. Las Vegas Paving found the Super 1800-2 with optional SprayJet module from Vögele fit the bill.

With its new Super 1800-2 SprayJet paver, Las Vegas Paving now is able to undertake pavement preservation contracts as agencies like Clark County, Nev., use available funds to prolong the life of pavement structures in its desert locale.

Las Vegas Paving acquired its Super 1800-2 SprayJet in early 2010, and has been using it for UTACS ever since. “We were the new kids on the block with this process,” says Clark Webster, general superintendent. “2010 was our first year paving UTACS, and we were concerned that interest would not last, but agencies are still interested.”

Late in 2010, Las Vegas Paving was applying a UTACS to busy Jones Avenue between Tropicana Avenue and Russell Road for the Clark County Department of Public Works. This 2,700-ton job involved three lanes each way, including shoulders and turn pockets. “Jones Avenue is a piece of a larger contract we have with the county, with each piece being anywhere from 15,000 to 20,000 square yards of UTACS,” Webster says. “Jones was a 1-inch deep UTACS, with almost 100-percent passing 1/2-inch with some fines.”

On Jones, warm polymer-modified emulsion was being sprayed directly ahead of the screed via spray bars on each side of the Super 1800-2 SprayJet at a rate of 13/100-gallon per square yard. “It’s not unlike a prime or tack coat, but it provides much more coverage,” Webster says. “And no one can run on it. The Super 1800-2 places the coat behind the wheels but ahead of the material, so cars or our haul vehicles can’t drive over it and pick up the sticky, polymer-modified emulsion. It gives us the best of both worlds – we are able to use a polymer-modified emulsion without having the mess of tires tracking it everywhere.”

Talks to Editor-in-Chief John Latta

The chairman and chief executive officer of Caterpillar joined the giant company in 1975. He held posts in finance and planning positions in South America and Japan, and was elected a vice president in 1995, serving as chief financial officer. In 1998, he became vice president with responsibility for the Engine Products Division. Oberhelman was elected a group president and member of Caterpillar’s executive office in 2002. In October 2009, he became vice chairman and CEO-elect, leading a team that developed the company’s future strategic plan. He was elected CEO and a board member in July 2010, and chairman November 1, 2010.

If you assess the economy-infrastructure connection, what do you see today and tomorrow?

The underlying problem is the amount of unfunded liability the government has racked up over the past 20 years. That pressure, as it manifests itself in the next 10 years, will mean pressure on discretionary government spending – primarily entitlements, which are going to have to be curtailed greatly before it’s all over with. But the pressure on everything else, in the meantime, really is going to force a hard look at what little money is left for this country to invest in infrastructure. The amount of funding for all of that [infrastructure] . . . is going to get squeezed greatly. So what it will do is pressure the political people to rally priorities around infrastructure.

Meanwhile – and I’ve spent a lot of time talking to Congresspeople about this – while we are constricting our infrastructure investment in this country, actually making us less competitive, the major trading forces in the world are increasing their investment in infrastructure like we used to do years ago when we were strong. And it’s not just China; it’s India, it’s Brazil, it’s just about everywhere where there is money and debt available. They’re making themselves more competitive. That worries me for American manufacturing jobs. Part of the reason we had such a long run as an economic superpower was because every part of our economy was competitive, from states to companies to the country, the whole works. And we’re going backwards while others are going forward. I’ve been trying to really sound that alarm in Washington, but what you get there is, “Doug, you’re here in Washington and you want us to spend money on infrastructure, but yet in the next breath you tell me to cut the deficit.” Correct! Because I remember when we got it all done. We prioritized infrastructure strongly enough and paid people unemployment and Social Security and stuff, and did everything else that you do to make your country competitive. What’s happened is that we’ve skewed the spending so badly in the past 25 years that there’s nothing left to make us competitive.

So America doesn’t think big enough any more?

I’ll give you an example. I was just in Amsterdam … the Dutch have decided they are going to increase the size of their harbors, so they are dredging an eight-mile-long, deep canal to harbor ships bringing trade out of Europe because they see that as a core business of Holland … they want to be the most competitive port in Europe. That’s the comparison I’m talking about. Nobody here is thinking that big.

Are we on course for a Japanese economic model?

No. No. I don’t think so, or a European model. The unbelievable wonder about the American economy and the system is its dynamism. The 2010 election was a first step in a massive changeover in how this country thinks about itself and thus elected political leaders in a way that made big changes. If we are in this debate in the next year going into the 2012 election, this country will do it again. This is not the worse crisis we’ve had in this country and we’ve always flourished afterwards … I’m convinced we’ll do it this time. The problem is – there are several problems – one is that we have had a 25-year tailwind in interest rates and a 25-year-plus period on a tailwind of government spending via debt … going forward we are not going to have that big structural drop in interest rates that we’ve seen since the early ‘80s and we’re going to have government debt to pay back.

Are we on course for a new industry economic model for transportation infrastructure industries?

It’s a different period coming up, but it doesn’t mean that this country can’t be strong. What does all this mean for better roads? I mean my better roads, not yours. It’s going to be tough, but I am convinced that with the industry that is left after this, whether it is one year or five years, we’re going to see the most competitive set of roadbuilders and infrastructure suppliers that this world has ever seen. And we’re going to see the ability to do whatever the metrics are – miles per day or tons per mile – in numbers we’ve never seen before … this prolonged recession for this contractor base is forcing them to really be efficient and to consolidate, and those that come through this will really be good. There is a tremendous pull from today’s contractor base on sustainability. Hot mix to warm mix, warm mix to cold mix, jobsite management of fleets, everything to reduce fuel and to reduce the CO2 footprint … reducing fuel reduces owning and operating [costs], which is a huge piece of the contractor’s cost structure, and they are going to force it back on us.

If you owned a construction company, how you would you proceed today?

You know, I’ve had more contractor and customer calls who have asked me that question than you can imagine. I have been surprised, and my advice is sort of consistent with what we’ve done here: cost, cost, cost; growth, growth, growth. And that usually means consolidation in the case of growth … the contractor base can consolidate and handle cost and get growth, but you can’t leave any fat on the bone; it’s all got to be lean muscle, which is similar to what we’ve done and are trying to do here at Caterpillar. I really believe the contractors who come through this will be lean and mean, and it will be good for our industry.

You are suggesting governments will have to change the way they approach infrastructure management.

The great good that is coming out of this fiscal mess where there just aren’t funds is that government at all levels is going to be forced to be efficient … never would have had that if we are not in crisis. The longer that crisis goes on, the more efficient government is going to be. Shut the funding off, and there are smart people at all levels of government, they’ll figure out ways to be efficient but there hasn’t been that hot torch on government until now to force them to do it. Change … is coming.

Infrastructure doesn’t seem high enough on the public or political agenda.

It’s hard to say. I can see one path out … the U.S. does decide that infrastructure is a priority and we put investment back into it and things happen pretty quickly and that’s kind of the traditional approach. But it will be a lot more selective, I think. If there is one thing that killed the reputation of infrastructure, it was the “bridge to nowhere.” That has done more to harm our industry than anything else. That leads right into a discussion on earmarks and are those jobs, those projects, really necessary. I have been very surprised in my role here when I talk to political leaders how, in many cases, infrastructure has gotten such a bad name because of the bridge to nowhere and because of pork barrel projects that don’t reach the national priority … one of the nice things about this fiscal situation is that it will weed that stuff out, too, because there’s just not money to do it. But the bridge to nowhere in its broadest – not just the bridge in Alaska, necessarily – but the concept of the bridge to nowhere really hurt this industry. Our industry was the innocent bystander victim of that … it was the politicians who brought us these kinds of things and funded them without the cost benefit and really without the national priority or investment priority they needed.

So we need more public awareness, more public support?

Yes. When I was a kid, a lot of the projects had a sign saying, “Your tax dollars at work.” I remember them, it was a positive image, and you felt good about your tax dollars at work. Everybody felt good about it, because you were getting a new road or a new curb or a new this or that. Well, we just saw a year ago your Stimulus dollars at work and the country came apart over it. Now, it was a ridiculous thing. So what has happened in that 30-year period? I don’t know, but something has.

As an OEM, what do you see immediately ahead in equipment?

The next horizon is the very efficient use of technology at the jobsite level. My favorite example is a 25-acre parking lot. With a grade, without a grade, with bumps, without bumps, whatever. One pass being very fine GPS setting, one pass being very fine gradations at the ground engagement point. Imagine doing that in one pass with a bulldozer, a motor grader. Can we do that in one pass with technology? It’s being done … not every day, but it’s out there. Imagine the fuel economy and CO2 footprint with that kind of efficiency, compared to the old days of cut-and-fill with stakes. Or you take 2 or 3 inches at a time and resurvey. Imagine doing it with one pass on that parking lot. That’s an easy kind of over-simplified example, but I think it makes my point that the technology we are about to embark on will be a breakthrough, and it isn’t so much centered around what the machine can do as what you have to have incorporated at the jobsite. The pull from customers for this is huge.

Efficiency will improve, dramatically?

Yes. You can’t go back to the $1 million a mile, or whatever, we want it at $700,000 a mile, or whatever … because this is all there’s going to be, so figure it out. And we will all do that collectively.

It sounds as though it’s not new technology alone that we need, but better ways to employ what we have on the jobsite?

Even broader. Let’s take another example … let’s use a simple one, say a new country road cut through to two small communities, where the county specs come out only digitally; the latitude, longitude and altitude are already provided in there to the millimeter. So you bid the job that way, you enter it into your machine and you stand back and watch it go. Think about the fuel efficiency and CO2 footprint on something like that. That is happening today. We are on the edge of this. But when you multiply it out, think what can happen. Here’s another message for contractors: Imagine the early adopters of this – they’ll blow everybody away because you won’t be able to compete with them when you’re cutting three times. There’s a tremendous pull for this and we are spending a lot of time and money on it; we are on the verge of it and using it already on some jobsites today. This is coming, and it’s sooner rather than later.

How physically damaged is the infrastructure that we have?

I am not one who believes our infrastructure is past the point of no return. I do believe our infrastructure is too antiquated to be competitive in many cases and most ports are in that category, most airports are in that category, our river system is certainly in that category. The Interstate highway system is, while probably not adequate for the amount of traffic we have, not as bad. Having said that, I don’t think that matters, because if we want jobs in this country, we’ve got to look at our competition … because if we are not upgrading and competing, it’s not going to matter if you are one lane behind or two. In this competitive world, if you are not going to lead, you are in trouble.

Will transportation infrastructure still be a job-intensive industry?

Oh yeah, definitely. We will get fewer labor hours per mile. That’s been a long-term trend, but it’s still a fairly intensive industry. When you go upstream in the supply chain to aggregate producers and cement producers and steel producers, it’s a pretty labor-intensive industry. It will be more efficient, but it will still have a lot of labor content.

You are an optimistic thinker about our future?

I am. I’ve got to be in this job.

A war is being waged on noise generated by pavements and highways.

By Tom Kuennen, Contributing Editor

Today, highway noise is considered an undesirable emission, just as if it were a noxious gas out of the tailpipe. But road designs can do much to attenuate highway noise.

These include active methods to quell noise created at the pavement-tire interface, such as variable transverse groove patterns on concrete and the new Next Generation Concrete Surface (NGCS), and thin and thick open-graded or porous asphalt friction courses.

But they also include passive methods, such as sound walls, vegetation screens, earth berms, recessed pavements, or combinations of the foregoing.

And even as the techniques of active and passive highway noise suppression are refined, methods used to measure noise are getting more sophisticated amid a political climate of less tolerance for highway noise in our cities and neighborhoods.

Keeping it Down

New solutions are coming in to play to control noise from America’s Interstate highways, primary highways and arterial streets. Road agencies are spending more on noise mitigation. On new or capacity improvement projects, sound walls that were once considered an extravagance are now standard procedure.

Engineers are finding that the best solution to highway noise is a combination of sound wall, appropriate vegetation and a quieter pavement surface. Any combination of the three elements will help, because noise barriers can cost an average of $3.9 million per mile, according to current estimates by the Washington State DOT, with lower costs for rural barriers, and higher for urban.

Producing a low-noise diamond ground surface – the NGSC – requires creating uniform and consistent negative-land profiles

Highway noise barriers can be of many configurations, including recycled plastic, wood, evergreens, gabion walls and precast concrete panels. Trees — such as stands of thick evergreens — have the potential to replace noise barriers, and are aesthetically pleasing, but are effective only in deep stands, requiring additional strips of right-of-way, as much as 100 feet wide.

Efforts to limit highway noise have focused on barriers. But because most of the noise originates at the tire-pavement interface, use of “quiet pavements” to quell noise there makes sense.

For portland cement concrete pavements, texture is added to improve friction and driver control, but done incorrectly it can add to pavement noise. Tine or groove depth, width, spacing and orientation are all major factors affecting tire-pavement noise. Transverse tinings with uniformly spaced tines a half inch or greater have been found to produce an objectionable tone, with pressure spikes at specific frequencies, that users interpret as a tire “whine.” Randomly varying the transverse tine spacing, or skewing it, can reduce the tonal-quality problems.

Sophisticated asphalt pavement designs – such as polymer-modified, open-graded friction courses (OGFCs) – offer greater tire-pavement noise reduction than conventional asphalt mixes. Also, their porous nature also allows fast drainage of water and eliminates the problems of tire spray, glare and hydroplaning.

Even as the industry improves noise suppression practice, a new rule from the Federal Highway Administration takes effect this month (July 13). Articulated last year, the final rulemaking for 23 CFR 772, Procedures for Abatement of Highway Traffic Noise and Construction Noise, fine-tunes expectations for highway noise reduction and describes a three-part approach to highway noise:

• Noise-Compatible Planning. Local governments should regulate land uses to restrict noise-sensitive uses adjacent to highways.

• Source Control. EPA noise regulations set the maximum noise level 50 feet from the centerline of travel at 80 A-weighted decibels.

• Highway Project Noise Mitigation. FHWA sets a five-step process for transportation agencies managing highway project planning and design to identify and abate highway noise impacts.

Download a summary of the new rules at environment.fhwa.dot.gov/strmlng/newsletters/sep10nl.pdf The complete final rule may be accessed at]edocket.access.gpo.gov/2010/2010-15848.htm

A recap of current federal and state initiatives in noise suppression – including a look at sound-absorbing noise walls – appears in the December 2010 ROAD SCIENCE (see Gaining Influence in 2011, December 2010, pp. 9-17).

Next-Generation Concrete Surface

This year, the concrete industry launched a portland cement concrete surface that will suppress noise from concrete pavements while enhancing friction and smoothness. A refinement of the pavement diamond-grinding process, the Next Generation Concrete Surface (NGCS) is being promoted by the International Grooving & Grinding Association and its allies, the American Concrete Pavement Association, Portland Cement Association and Purdue University.

New-generation sound wall on Windsor-Essex Parkway in Ontario boasts aesthetic pattern and clear, transparent panels which obviate ‘Berlin Wall’ look

When this innovative surface was used on an urban highway in Duluth, the response was overwhelming, IGGA reports. “Residents have called in asking how the roads became so quiet and it has even made the front page in the local newspapers,” says IGGA Executive Director John Roberts.

The best way to understand the difference in the sound level with NGCS is to experience it; a high-traffic freeway with 240 vehicles will now sound comparable to only 120 vehicles of traffic, a substantial reduction in sound, IGGA reports. This is a considerable decrease for areas with a greater need for quieter roads, such as urban or residential areas.

The NGCS is a diamond saw-cut surface designed to provide a consistent profile absent of positive or upward texture, resulting in a uniform land profile design with a predominantly negative texture. NGCS is a hybrid texture that resembles a combination of diamond grinding and longitudinal grooving.

On-Board Sound Intensity measurement processing of sound at tire-pavement interface creates graphic – integrated with Google Earth image – reporting existing highway noise performance.

The texture is most easily constructed in a two-pass operation using diamond-tipped saw blades mounted on conventional diamond-grinding and grooving equipment. Testing has shown that these textures can be used for both new construction and rehabilitation of existing surfaces.

The construction method has two separate operations, reports the Washington State DOT in its April 2011 report, Evaluation of Long-Term Pavement Performance and Noise Characteristics of the Next Generation Concrete Surface. The first operation creates a flush ground surface and eliminates the joint or crack faults while providing lateral drainage by maintaining a constant cross-slope between grinding extremities in each lane.

The second operation provides the longitudinal grooves, Washington DOT reports. The longitudinal grooves are 0.125 inches wide, and 0.125 to 0.375 inches deep. The longitudinal grooves are spaced approximately 0.5 inches center-to-center. The grooves are constructed parallel to the centerline.

The NGCS is being promoted following three years of research at the Minnesota Road Research Project (MnROAD), the world’s largest and most comprehensive outdoor pavement laboratory.

In early 2011, new NGCS test sections were constructed at the Virginia Tech Transportation Institute’s Smart Road test facility near Blacksburg, Va. In January 2011, three test strips situated on two test areas were constructed, including a conventionally diamond-ground section, and an area that was conventional followed by longitudinal grooving of each half of the lane using two different groove spacings of 0.5 and 0.75 inches.

New Texturing Guide Specs

Also this spring, two new approaches were articulated for guide specifications for reducing tire-pavement noise on PCC pavements.

In the May 2011 publication, Concrete Pavement Specifications for Reducing Tire-Pavement Noise, – developed by the Concrete Pavement Surface Characteristics Program (CPSCP) and published by the National Concrete Pavement Technology Center (CPTC) at Iowa State University – authors Robert Otto Rasmussen and Richard Sohaney of The Transtec Group, and Paul Wiegand of the Institute for Transportation at Iowa State, describe method-based (prescriptive) specs and end-result specs for suppressing PCC pavement-generated noise.

For the methods-based specs, four guide specifications (GS-1 through GS-4) have been developed. “[They] correspond to the four most commonly used concrete pavement textures: diamond grinding, drag (artificial turf), longitudinal tining and transverse tining,” the authors write. “The practices described in the specifications have been demonstrated to increase the likelihood of constructing a durable, quieter concrete surface. Central to the specification is guidance for texturing the concrete surface, given that texture geometry has a paramount effect on tire-pavement noise. Guidance is also provided for curing to improve strength and durability of the surface, and thereby improve texture durability.”

For the end-result specs, a recommended practice (PP-1) has been developed that includes guidance and sample specification language for owner agencies to evaluate tire-pavement noise of new concrete pavement surfaces. “The overall sound intensity level measured with the onboard sound intensity (OBSI) test method is designated as the quality characteristic,” the authors write.

The authors single out transverse tining technique as a major culprit in PCC pavement noise. “Both longitudinal and transverse tining are routinely used by owner-agencies, particularly for high-speed facilities,” Rasmussen, Sohaney and Wiegand wrote in May. “Achieving a quieter concrete surface is possible, but requires additional control, particularly for transverse tining, which is often associated with some of the loudest concrete pavements.”

When using tined textures, grooves are imparted in the surface of a pavement while the concrete is plastic, they say. For best results, application of a drag pre-texture should be followed by subsequent tining.

“For longitudinal tining,” the authors write, “the nominal spacing of the tines is 3/4 inch. For transverse tining, nominal spacing of 1/2 inch is specified. The nominal depth of the tined grooves in the plastic concrete is 1/8 inch.”

The Tech Brief may be downloaded from the CPTC at cptechcenter.org/publications/surface_char_specs_tech_brief.pdf and the individual guide specs can be found at cptechcenter.org/projects/surface-characteristics/index.cfm

New Ways to Measure Noise

Integral to concrete’s new attack on noise is a shift from measuring sound pressure remotely, to sound intensity directly at the source, the tire-pavement interface.

The key recommendations developed by the Concrete Pavement Surface Characteristics Center are largely based on tire-pavement noise tests conducted worldwide using microphones right at the tire moving on the pavement, write Rasmussen, Sohaney and Wiegand in a companion Tech Brief issued in May, Measuring and Reporting Tire-Pavement Noise Using On-Board Sound Intensity (OBSI).

“OBSI measures tire-pavement noise at the source using microphones in a sound-intensity probe configuration mounted to the outside of a vehicle, near the tire-pavement interface,” they say. “Measurements are performed while the test vehicle drives across the pavement of interest.”

Sound and noise can be a relative experience. A rock concert produces sound levels at about 110 decibels. A quiet night actually produces some 30 decibels of sound. But only levels above 85 to 90 decibels are thought to pose health risks.

Sound levels are measured exponentially. One expert describes it this way: Assuming two planes with the same individual sound level (3 decibels) are added for every double. If a plane taking off creates 100 decibels of noise, two planes would make 103 decibels, four planes 106 decibels, and eight 109. Highways, roads and streets routinely produce decibel readings of from 65 to 85 decibels.

When a sound level (such as 90 dBA) is reported, it is most often a measure of the amplitude of sound pressure changes, the authors add. “Sound intensity is different from sound pressure in that it has both amplitude and an associated direction,” they write, making it a more meaningful criterion for analyzing noise emissions.

Benefits of OBSI include:

• The directional characteristic of the probe makes it better-suited for measuring a specific noise source, while attenuating sounds from other sources in other directions (such as engine or exhaust noise);

• Sound intensity is much less contaminated by “random” noise, such as wind noise generated as the vehicle is moving; and

• Because sound intensity measures the acoustic energy propagating away from the source to the roadside, it correlates well with sound measured at the roadside (known as pass-by or wayside measurements).

The new Tech Brief may be downloaded atcptechcenter.org/publications/surface_char_specs_tech_brief.pdf

OGFCs Quell Noise at Surface

Open-graded friction courses offer state DOTs a better-performing, driver-friendly pavement. These new-design OGFC pavements feature an “open” aggregate structure (without fines) in which larger-sized aggregate is held in place by polymer-modified and fiber-modified Superpave performance-graded liquid asphalts.

This open structure of 15 percent or more voids allows water to drain right through the driving or friction course to an impervious intermediate course below, and out the side and into edge drains or roadside ditches. The result is the near-complete elimination of tire spray and hydroplaning, making a safer pavement.

Also, because noise generated at the tire/pavement interface is attenuated within the spaces between the aggregate, they are significantly quieter pavements. The noise reduction can be on the order of 3 to 5 decibels.

An OGFC describes a layer of asphalt that incorporates a skeleton of uniform aggregate size with a minimum of fines. Typically, OGFCs in the past have a void content as low as 12 percent and as high as 15 or 16 percent. But the new generation of OGFCs that are being built in Europe have considerably higher air void contents, up in the range of 17 to 22 percent. They are more open, with more voids.

Most OGFCs are 3/4-inch thick, and never thicker than 2 inches. The OGFC should be elevated above the shoulder, as the water drains onto the shoulder and hence to a roadside ditch. Open-graded, proprietary thin surfacings such as Novachip and its clones qualify as OGFCs.

In dense-graded asphalt mixtures, reports The Asphalt Institute, a thin film of asphalt plus compaction effort – are required to keep the mix glued together. In short, the final density of dense-graded mixes is a direct measure of the strength and durability of the mix. But the OGFC mix, according to the AI, uses a grading of mostly 3/8-inch stone, the idea being to build up a thick film of asphalt on the stone without the mixture draining or flushing. The asphalt film thickness is usually four to six times that of a dense-graded mix.

“If properly designed, the asphalt in an OGFC does two jobs,” AI says. “First, it acts as a binder or glue. Second, since the mix is open to water and air, it acts as a waterproofing agent and protective coating to resist oxidation and rapid aging of the asphalt cement itself.”

Today’s OGFCs are polymer-modified and include spun mineral or cellulose fibers to preclude drain-down of asphalt binder during transport and placement. Use of polymer modifier or fiber does not preclude the other; instead, each complement the other in the liquid asphalt. The fibers disperse evenly, and despite their tiny size, overlap and form a mat, which keeps the liquid asphalt from draining from the top to the bottom of the layer before it cools, not unlike the action of gauze in keeping a wound from seeping.

But an application in May 2011 in South Carolina showed that fibers can be eliminated from an open-graded porous asphalt pavement. Use of Evotherm warm-mix asphalt additive permitted an open-graded mix that did not require addition of mineral or cellulose fibers to prevent draindown, a substantial savings. It also permitted elimination of lime as an adhesion promoter resulting in substantial savings.

Sound Walls Go Mainstream

From a start as an extravagance decades ago, sound walls now have gone mainstream, as they are seen more and more on new urban and suburban expressway projects, and as retrofits on existing highways.

The FHWA requires DOTs to complete a sound study any time it plans to add through lanes to an existing highway or change the location of a road. “Sound walls can help lessen the noise impacts of the roadway improvement and provides noticeable sound reduction for houses closest to the highway,” says the Missouri DOT.

A sound wall can reduce noise levels from 5 to 10 decibels. In Missouri, communities are eligible for a sound wall only if noise levels are at 66 decibels or above. According to the Washington State DOT, 66 decibels was chosen as the impact threshold because researchers have shown that above this level, conversation between two people standing 3 feet apart and speaking in a normal voice is impaired.

Missouri criteria for construction of a sound wall includes:

• the sound wall must reduce noise levels by at least 5 decibels for all benefited homeowners,

• the sound wall must benefit more than one homeowner,

• the sound wall must be 18 feet or less in height,

• the sound wall must not pose a traffic safety hazard, and

• the majority of the benefited residents must agree that a sound wall is desired.

Sometimes state and local agencies will cooperate in construction of sound walls for existing freeways. For example, Missouri will conduct a sound study to review the need for sound mitigation near existing highways when cities and counties participate in the cost of the design and the construction of the wall. The local government agency must provide 50 percent of the design and construction cost. MoDOT will provide the 50 percent matching funds. If the construction cost of the sound wall project exceeds $30,000 per benefited resident, the local government agency must pay 100 percent of the cost above $30,000.

Sound walls can be a costly undertaking. In Washington State, the DOT estimates current construction costs are averaging $53 per square foot. “This translates into a 14-foot-high wall costing about $3.9 million per mile,” the DOT says. “Construction costs for rural barriers may be lower and urban barriers may be much higher. The higher urban costs are associated with the existence of other infrastructure – like retaining walls or water pipes – that may need to be retrofitted or moved to allow the placement of barrier.”

A Choice of Materials

Precast concrete panels – due to their quick erection capability in the field – constitute the bulk of sound walls today. Precast panels also permit aesthetic textures to be integrated into a project. They can be as bland as an imitation of hewn concrete block, or as attractive as a motif incorporating Native American designs, as seen often in the American Southwest.

Concrete panels and block are muscling out competing materials like wood, steel and plastic on a national basis, but in doing so quite often are going up against each other in bids. In 2000, concrete and block represented almost two-thirds of total material usage, according to a spokesman for the FHWA Office of Environment and Planning.

Because of the growth in sound wall applications, and the fact that highway noise barriers can be so expensive, barrier design must as efficient and cost-effective as possible. That’s why FHWA released, in March 1998, a state-of-the-art model for predicting noise impacts in the vicinity of highways, the FHWA Traffic Noise Model.

The current Version 2.5 was released in April 2004. The FHWA TNM is a computer program that incorporates advances in personal computer hardware and software to improve upon the accuracy and ease of modeling highway noise, including the design of effective, cost-efficient highway noise barriers. For more information, visit fhwa.dot.gov/environment/noise/traffic_noise_model

Although precast concrete and masonry are the leading materials for sound walls, wood often is thought of first for sound walls. Other competing materials include steel, plastic and recycled products. The concrete products industry is fighting against lower-priced materials by promoting lifecycle costing versus competing materials.

Wood has declined in usage because of durability problems compared to concrete, difficulties in cleaning of graffiti, and the disfavor of use of imported wood from tropical rain forests, which had been the prime source. Wood also suffers because preservatives such as creosote emit volatile organic compounds to the atmosphere.

Use of alternate materials may have been boosted with the January 1999 Transportation Research Board-sponsored publication of Noise Barriers Using Recycled-Plastic Lumber (Hag-Elsafi, Elwell, Glath and Hiris).

This paper, out of the New York State DOT, described use of “lumber” fashioned from recycled plastic extruded into classic lumber sizes, and placed in wood or steel frames. They mentioned then-competitive costs per square meter of $161-194 for plastic lumber with wood frames, and $226-269 with steel frames.

Playing The Cards You’re Dealt

(when they’re not very good)

How some city road managers cope with diminishing budgets

By Kirk Landers

With Stimulus money slowing to a trickle and local tax revenues still sagging, Better Roads interviewed a cross-section of city road managers to find out what they are doing with the funds they have available.

With the federal transportation program foundering, and state and local tax revenues locked in the throes of the Great Recession, road managers all over the country are struggling to maintain the integrity of pavements and bridges. While major interstates and high-volume freeways get funding priority in times like these, thousands of lane-miles of surface streets in metropolitan areas carry high volumes of traffic and are an essential part of area commerce and lifestyle. And beyond those high-volume roads are residential streets that, though low on the triage scale, have safety, environmental and political implications.

Given the sobering reality in rural communities where some paved roads are being returned to gravel due to inadequate funds (See “Weighing the Options,” Better Roads, April 2011), we wondered how their counterparts in urban/suburban America were being managed. To gather some idea of today’s urban road realities, we engaged a random assortment of city road managers in a series of informal conversations.

Our informal, unscientific conversational poll turned up both good news and bad news.

The bad news is what we expected: funds for roads are becoming desperately inadequate in many places, and there is an air of uncertainty almost everywhere due to the absence of a long-term federal program and chronic weakness in tax revenues at all levels of government.

The good news is that it’s not all bad news. Some city governments are finding reason — and resources — to pursue aggressive road programs. And even in cities where road funds have atrophied badly, road managers are employing new strategies and tactics to protect the public’s investment in road infrastructure until the Great Recession gives way to the Great Recovery.

Bridge Watch

Bridge repair and replacement can overwhelm any municipal road budget, even in the best of times, and in times like these, managers are scrambling to prevent the need for expensive interventions.

Liong So, a senior project manager in the City of Dallas (Texas) Public Works Department, says her agency keeps the city’s bridges in good condition by responding quickly to repair and maintenance needs. “One area we especially monitor is scouring on bridge columns,” she says. The agency’s strategy for bridge deck repairs now emphasizes longer-lasting interventions, she adds. “We still want to intervene quickly, but now, instead of a quick fix, we’ll do a full-depth repair, if the conditions warrant it.”

Rock Miller, a principal of Stantec, one of North America’s major highway and bridge consulting engineering firms, notes that bridge replacement has become an especially dicey proposition. “We are in an era of dwindling resources,” he observes. “We have to do more with less, but in many areas, the available funds aren’t even enough to cover maintenance expenses because funding has declined and maintenance costs have gone up.

“There have been a lot of innovations in pavement and bridge technology, but we don’t have the ability to fund them,” he notes.

Of course, when bridges become dangerously near the end of their service lives, communities often have to do something. That something, says Miller, may be tolling. He cites as an example a floating bridge in Seattle, which will sink in a few years. “The price tag for replacing that bridge is the entire budget capability of the region,” says Miller. “The best option they have is to rebuild it as a toll bridge, and we may see a lot of that sort of thing as time goes on.”

Miller notes that tolling projects are bondable. “That may be the only way to raise $300 million for a bridge for some agencies,” he says.

Miller adds that Illinois and Indiana are two states that have gotten money from the bond market with toll roads and bridges, while states like Texas and Florida are considering such projects and California leaders are discussing tolls for solo drivers in carpool lanes as a way of raising funds for roads and bridges.

Best Outcome Solutions

Every manager we interview emphasizes longer-lasting solutions as part of their agency’s urban road strategy today, though the tactics employed by each agency varied according to local needs and priorities.

For Ron Ditmars in Overland Park, Kan., the single most cost-effective pavement intervention is crack sealing. Ditmars is supervisor of public works maintenance for the city, which is part of the greater Kansas City metropolitan area and has a population of about 173,000.

“With revenue trends like they are, we’re focusing on maintenance technologies that cost the least and give the most return,” says Ditmars. The city’s maintenance priorities, he says, are crack sealing, milling and paving patches, and repairing base failures. In-house crews tend to the crack sealing and patching, and some of the base failures, while larger base repairs and milling and paving work are contracted out.

“We’re still evaluating which surface treatments give us the best return,” says Ditmars. The city has employed a variety of preventive maintenance interventions over the past decade, including microsurfacing, some chip seal and some slurry seals, in addition to conventional overlays. “We’ve been using a combination of overlays on a 28-year cycle with surface treatments every seven years,” says Ditmars. “If funds get really tight, we might have to push some of the surface treatments to eight years.”

Overland Park classifies its roads in three categories: residential, collectors and thoroughfares. The thoroughfares, says Ditmars, get milling and overlay interventions on a shorter cycle – 10 years or more – with microsurfacing treatments following five or six years later. Chip seals are not used on thoroughfares.

The city has been experimenting with several surface treatment options. A rejuvenating oil to treat aging surface asphalt has gotten negative public reception due to material being tracked into homes. The city is using different stone and oil combinations for its microsurfacing mixes, and officials there are looking at options like crumb rubber, river rock and hadite to either lower costs or extend service, or both.

Ditmars says the city also gives high priority to drainage for its streets, because water in the pavement can create expensive damage and safety problems. “One of our most important missions is to keep the underdrains open on some of our thoroughfares so the medians can drain properly,” says Ditmars. Similarly, when city crews repair failed bases, water is often the source of the problem, so they install underdrains as part of the repair.

Ground Failure Before Pavement Failure

For Mike Coffey, Alaska DOT maintenance and operations engineer, and his Fairbanks counterpart, Steve Potter, their state presents a set of road management problems that range from the unique to the nearly bizarre, but they have one thing in common with road managers everywhere: “We face higher expectations from the public every year,” says Coffey.

“The public wants a higher level of service and we try to provide that from a budget that generally doesn’t grow as fast as expectations.”

Because Alaska is a massive state with a small population, its transportation structure is different than other states. It derives a higher percentage of its road budget from federal funds, and the state DOT works more directly with city and local roads than in other states.

“We’re doing more with less, like everyone else,” says Coffey, of Alaska DOT. “In the old days we might have had three trucks and a grader on a job, now it’s one truck and a grader. All the trucks have attachments like front plows, belly blades, and sanders so they can do multiple tasks.”

Coffey says the agency has reduced its inventory of specialized equipment, in some cases by renting, and in other by replacing specialized machines with multi-use units.

As in other places, safety problems trump all other priorities, even in this tight budget era. In the Fairbanks area, the state has recently invested in a salt-brining system to deal with a changing climate that makes the fall to winter transition longer, with more freeze-thaw cycles. Coffey says the transition begins in October and often includes heavy and freezing rains, in addition to traditional winter weather.

“We were exhausting our supply of brine that was based on a more traditional, shorter transition to winter,” says Coffey, “and that is dangerous.” The new system has five stations that produce an enhanced brine that includes sodium chloride and an organic ingredient.

In trying to stretch pavement life, Alaska’s road professionals face some unique problems. In the southeastern part of the state, cities like Anchorage and Juneau face the twin curse of soft local aggregate and a long season of studded tires that includes periods of clear streets. The result is premature rutting. To achieve a longer-lasting, more cost-effective solution, the DOT is importing harder aggregate from British Columbia for its surface asphalt mixes.

In Fairbanks and the northern part of the state, the most severe and unique road problems stem from the fact that roads are built on permafrost, which becomes a weak, unstable base when it thaws in the spring. “We can build a 20- to 25-year pavement,” says Coffey, “but the ground fails before the pavement does.”

Northern Alaska’s extreme weather and soil combination can produce awe-inspiring effects in the spring, including roller-coaster-like undulations and long horizontal cracks in the pavement. “The horizontal cracks stem from the fact that the roadway fill is thicker at the centerline and gets thinner as you move out,” explains Coffey. “If the road has a 2:1 slope, there may be 6 feet of fill under the center line tapering to 4 feet of fill just beyond the edge of the pavement. This means the center is more insulated than the shoulders from the cold and heat, and that causes the differential warming of the permafrost under the road and the damage that follows.”

As a result, Alaska reclaims a lot of surface pavement each summer in the north and invests less in traditional pavement maintenance interventions used in the lower 48 states.

The DOT has also worked to reduce the destructive effects of the pavement/permafrost temperature differentiation by developing its own snow plowing tactics. “We’re in the refrigeration business,” laughs Coffey. “To reduce the effects of differential heating, we’ve been experimenting with plowing the road shoulders when we clear the streets. If the snow is piled on the shoulder, it insulates that ground and increases the temperature differential between the pavement and the ground next to it, which causes cracking.” The shoulder-plowing technique has been an effective tactic in reducing that problem.

For Fairbanks’ maintenance supervisor Potter, the plowing solution is an important one. “We can’t use chemicals in much of the winter because our temperatures are too low,” he says. And winters are much longer in Fairbanks than elsewhere in the U.S. — “our temperatures go below zero F by the end of October and ground temperatures remain below zero F well into April.”

Potter’s road management interventions include prolific use of foamed asphalt and cold recycling, as well as warm-mix asphalt and some testing of open-graded asphalt.

Cities Taking Action

Paul Klope and the city of Eugene, Ore., serve to remind us that local governments find the means to do what must be done. Eugene, a city of 138,000 in west-central Oregon, passed a five-year, $36-million bond measure in 2008 to repair the city’s long-neglected roads. This, combined with a city gas tax, federal STP-U (Surface Transportation Program–Urban) funds, some recent state and county funding and a chunk of Stimulus money ramped up the funds to provide what Klope calls “an amazingly robust” pavement program. These funding levels will continue for at least another couple of years.

“The investment was long overdue and the timing was a blessing for everyone,” says Klope. “We’re getting great bid prices because of the competition for work, but it’s good for the contractors, too, because we’re able to pave even more streets.”

The size of the city’s program has given Eugene’s pavement managers an opportunity to invest in several pavement technologies that are projected to yield higher cost-benefit performance than the pavements they replace.

One area of special emphasis is employing recycled asphalt shingles (RAS) as part of the city’s asphalt mixes. “The Oregon spec allows us to use 30-percent reclaimed asphalt pavement (RAP), or 20-percent RAP and 5-percent RAS,” says Klope.

“We won’t know if there’s any financial savings until we’ve done it, but using RAS helps us achieve city council goals for environmental stewardship,” says Klope. “The process is new to local contractors, so we’ll see what happens when we build more projects where RAS is allowed.”

Eugene changed its design policies in 2008, shifting from thin pavements over thick rock bases to full-depth asphalt to reduce the long-term costs of its road program. Research shows that the city’s 30- and 40-year-old full-depth pavements are in much better structural condition than traditional thin asphalt streets and much less expensive to rehabilitate.

The city began using full-depth reclamation (FDR) in the reconstruction of selected streets in 2009. “We have poor soils here, so we use FDR with a portland cement additive to create a strong platform,” explains Klope. “We started with three local streets and it went so well that we added more local streets and an arterial last year. Because of local soil conditions, Klope says the city’s FDR process digs deeper into the soil than typical reclamation practices and can use a much higher mix of portland cement — up to 8 percent.

Eugene is also testing whitetopping as a solution for an intersection that has a high volume of heavy trucks. The city milled 6 inches of the old asphalt pavement and placed 6 inches of concrete on top of it. It is the city’s first use of whitetopping on a street, though the technology has commonly been used for bike paths in Eugene.

Eugene is also making a major commitment to warm-mix asphalt, using it for almost all of its paving projects since 2009 – a total of more than 120,000 tons so far. The city adopted warm mix for environmental reasons and in hopes of some slight gain in lifecycle cost efficiency. “We like the higher-effect asphalt content,” says Klope, “and we hope that translates into longer life. Meanwhile, it meets our community’s environmental goals and it’s good for workers.”

Klope says Eugene contractors have found warm mix a little easier and faster to compact than hot mix, but they don’t like raking it; therefore, small, irregular areas are often done with hot mix.

Life Goes On

While the specter of inadequate budgets hangs over many state and local road agencies today, most road agencies are trying to maintain current levels of pavement and bridge condition until the economy recovers and budgets return to normal levels.

“Metro government has put a lot of its efforts into maintenance activities, with potholing, overlays and crack sealing to extend our pavement life with more cost-effective measures,” says Jeremy Raney, executive administrator in the Louisville, Ky., Department of Public Works and Assets. “Most of our efforts are currently focused on maintenance of existing structures and replacing those that have more severe deterioration.”

Like many other road departments, Louisville was able to use Stimulus funds for critical upgrades, but now faces a much tighter budget and more limited capabilities.

Still, says Raney, Louisville is using its asset management system to establish priorities for bridge and pavement rehabilitation, and the city’s maintenance department is focused on critical preservation activities, including replacement of deteriorated cross drains and shoulder repairs.

Ironically, our conversation with Raney was delayed and truncated by severe weather and flooding in the Louisville area last spring, a reminder to us all in this period of taut budgets and growing needs that all strategies and tactics are subject to the whims of natural events.

Working a Watershed in Winter

Recession or not, the environment needs help

Even in the dark shadows of the Great Recession, the need to develop road designs with sounder environmental attributes is a driving force in many areas.

In the Twin Cities suburb of Robbinsdale, a partnership of road and watershed management agencies is working with the Minnesota Asphalt Pavement Association and the consulting firm of Wenck Associates on a three-year study to see if the use of porous asphalt can reduce the need for road salt in an environmentally sensitive watershed area.

The Shingle Creek Paired Intersection Project was launched in 2009 with a $282,000 research grant and the construction of 150-foot test sections of porous asphalt and conventional asphalt on a Robbinsdale residential street with a sandy subgrade. A second test site was built in 2010 on a clay/loam subgrade.

“We will monitor these sections for three years,” says Ed Matthiesen, a consultant with Wenck Associates. “We want to estimate the effectiveness of porous asphalt in reducing the need for salt as a de-icer and determine whether porous asphalt can stand up to the rigors of residential street use.” In addition, the study will determine short-term maintenance requirements and project long-term requirements, and the team will measure the water quality and quantity performance of porous asphalt.

Though the study won’t be completed until 2013, the intermediate results have been promising. “The control sections with salt tend to melt faster than the unsalted porous asphalt sections, but there is less refreezing of melted snow and ice on the porous pavement,” says Matthiesen. “And it appears to work just as well as salted pavement at clearing ice buildup.”

After two winters for one section, and one winter for the other, Matthiesen says the porous pavements are holding up well with no visible signs of distress from traffic, plows or weather.

The porous test sections include 1.5 to 2.5 inches of asphalt with 40-percent void, a choker layer of 0.5 to 1.0 inches, and a 0.25- to 0.75-inch layer of porous aggregate. Cellulose fiber and mineral filler were added to the binder to achieve a draindown of less than 0.3 percent.

Temperature sensors have shown the porous asphalt has insulating properties; the test sections are warmer than the control sections an inch below the surface. In addition, the porous sections have been more responsive to solar radiation, producing a faster melt and more bare pavement on sunny days compared to the control sections.