Our exclusive annual research into bridge conditions in the United States.

Over regulated, underfunded and disheartening.”

That’s how Brian Olson, bridge replacement engineer with the South Dakota Department of Transportation, describes the past 12 months for his department in terms of work and funding.

There is no avoiding the obvious – our economy and spending on transportation infrastructure are both weak and showing precious little signs of a sudden, strong and prolonged revival. But despite the doom and gloom that’s been cast on U.S. infrastructure, the state of the nation’s bridges could be said to be a little bit encouraging.

A Five-Year Look at America’s Bridge Inventory

Better Roads’ annual Bridge Inventory reveals that the total number of structurally deficient (SD) and functionally obsolete (FO) bridges (combined) has dropped from 23.3 percent last year to 22.7 percent this year. That means 136,816 of the total 602,091 bridges surveyed are SD/FO (combined) this year. Last year, 600,513 bridges were surveyed and 139,620 of them were SD/FO (combined).

Of the nation’s 292,085 total interstate and state bridges, 59,250, or 20.3 percent, are SD/FO (combined). In 2010, Better Roads reported 61,149, or 21 percent, of the 291,034 total interstate and state bridges were SD/FO (combined).

Highest Percentage of SD/FO State/Interstate bridges

There are 310,006 total city/county/township bridges in the United States, and 77,566 – or 25 percent – are SD/FO (combined). In 2010, of the 309,479 reported total city/county/township bridges, 78,471 (25 percent) were considered SD/FO (combined).

There has been steady decline in the number of overall SD/FO combined bridges in the United States, as well as the number of SD/FO combined bridges at the interstate and state level and at the city/county/township level since Better Roads first began archiving its Bridge Inventory in 1985. In fact, there has been a 19.8-percent decline in overall total SD/FO combined bridges. In 1985, 42.5 percent of the total 586,241 bridges surveyed in the nation were SD/FO combined. (The survey was started in 1979, but the data were not archived until 1985, the year the survey received responses from all 50 states and the District of Columbia.) Ten years later, 591,205 total bridges were surveyed and 187,504, or 31.7 percent, were reported as SD/FO (combined). In 2005, the Bridge Inventory’s total number of surveyed bridges grew to 595,625, but only 25 percent, or 149,126 were SD/FO (combined). From 2006 to 2011, there has been a 1.8-percent drop – from 24.5 percent to the current 22.7 percent – in the number of SD/FO combined bridges.

The top states with the most city/county/township SD/FO bridges

Looking at the numbers state-by-state, the majority of jurisdictions have slightly, decreased the number of SD/FO (combined) bridges. It may be baby steps, but it’s a move in the right direction.

But one exception with a significant rise in percentage was Washington, D.C., which has jumped from 41 percent in 2007 to a current rate of 61 percent.

Wyoming moved from 12 percent in 2007 to 14 percent in 2011; Illinois from 18 percent in 2007 to 16 percent in 2010 but back up to 17 percent this year; Georgia with a 1-percent decrease and increase – 20 percent in 2007, 19 percent from 2008 to 2009, 20 percent in 2010, and back down to 19 percent this year. Delaware has slowly increased, from 18 percent in 2007 to the current 20 percent. Connecticut was at 33 percent in 2007 and has been at 36 percent since 2008. Arizona had 6 percent of its total bridges SD/FO (combined) in 2007, but jumped to 10 percent in 2008 and then 11 percent in 2009, only to drop down a percentage point again in 2010 and remain there this year.

Alaska, California and Colorado also experienced increases of a percentage point between 2007 and 2010, but are now back down to the lowest percentage in five years. Alaska was at 22 percent in 2007, went up to 23 percent from 2008 to 2010, but went back down to 22 percent this year. California went from 18 percent in 2007 to 19 percent in 2008, but returned to 18 percent last year and has kept the status quo. Colorado had the same pattern. The Rocky Mountain State had 13 percent of its total bridges classified as SD/FO (combined) in 2007 and that increased to 14 percent in 2008, then dropped back down to 13 percent in 2010 and has stayed at this percentage.

Texas has the most bridges in the nation, 51,808 including a combination of interstate and state and city/county/township bridges, and just 8,949, or 17 percent, are considered SD/FO combined. The Longhorn State has seen a 3-percent improvement in the number of overall SD/FO combined bridges during the past five years, down from 20 percent to the current 17 percent. Breaking down this year’s numbers, 7,480 (14 percent) are SD and 1,469 (3 percent) are FO.

The D.C. Conundrum

It is the nation’s capital that has the highest percentage of combined SD/FO bridges. But the numbers come with some explanations – and perhaps more importantly a disagreement about definitions – from the District of Columbia’s DOT (DDOT).

Of the 199 total interstate and state bridges in the District of Columbia, 122 (61 percent) are SD/FO. (The designation for city/county/township bridges is not applicable because the entire city of Washington, D.C., is treated as a state.) Last year, 123, or 62 percent, of the District’s bridges were considered SD or FO, 7 percent more than in 2009, but down 1 percent of total SD/FO interstate and state bridges from 2010 to 2011.

Availability of funding remains one of the biggest challenges in reducing the rate of SD bridges, notes DDOT’s Don Cooney. Cooney noted this in his survey response to Better Roads in 2010 and repeated this sentiment again in this year’s survey. However, in a follow-up interview with DDOT after the Better Roads Bridge Inventory surveys were tabulated, Ronaldo Nicholson, chief engineer of DDOT, says the percentages don’t always tell the full story. Technically, the bridges in D.C. classified as FO don’t meet current American Association of State Highway and Transportation Officials (AASHTO) standards. “We are talking primarily the national highway system to meet the definition of FO,” Nicholson says. “That definition is in conflict with what the District is trying to do in terms of mobility. Our goal is to provide multimodal transportation.”

One problem is that D.C. is an urban area. Nicholson says DDOT doesn’t have the ability to widen some of the bridges and bring them up to the current AASHTO standards, and for that reason they are being classified as FO. The real estate isn’t available, he says. “I have to decrease lane width to have more access for bikes and pedestrians or for a shared pathway,” Nicholson points out. “So we are meeting our multimodal efforts, but we are still falling technically within the definition of functionally obsolete.”

But reducing the number of FO bridges will always be problematic. “Addressing FO bridges is a bigger problem because of our limited right-of-way,” Nicholson says. “Being functionally obsolete doesn’t mean that the bridges are less safe or functional. They just are not being used the way [for which] they were originally intended. Because we are in an urban environment, we do want people to slow down.”

This is just part of a much larger problem, Nicholson says. He suggests that the Federal Highway Administration (FHWA) and/or AASHTO need to relook at the definition of FO. “As a standing member for the committee of Bridges and Structures for AASHTO,” Nicholson says, “it’s time the states and DOTs relook at the definitions because they give a false perception to the general public about the health of our bridges.”

Nicholson says that, of the 12 percent of SD bridges in D.C., the agency is replacing about half of those. “Seven of our bridges will be coming off the SD list,” he says. “This year, we have already addressed five of those bridges, and two more are planned by the end of the year. We are not Texas or California. We only have 199 bridges. If I take 10 bridges off of the list, it takes the number of SD bridges down significantly.”

The rest of the rankings

Rhode Island is next in the highest percentage of reported SD/FO combined bridges. Taking the No. 2 spot – as it did last year – 371, or 49 percent, of the East Coast state’s total 751 bridges are SD/FO combined. This is a slight drop from last year. In 2010, Rhode Island reported that 417, or 53 percent of 789 total bridges were SD or FO. This year, the state reported that 296, or 49 percent, of its 607 total interstate and state bridges are SD/FO (combined). On a local level, 75 of 144 total city/county/township bridges, that’s 52 percent, are SD/FO combined.

So, there is some improvement from last year when Rhode Island reported 54 percent – 341 – of its 634 total interstate and state bridges in FO or SD condition – and 49 percent – 76 of 155 – of total city/county/township bridges in SD or FO condition.

The Aloha State ranks third for combined overall FO/SD bridges. Last year, Hawaii shared this ranking with Pennsylvania. This year, the State of Hawaii reported that it has 1,176 total bridges, and 449, or 38 percent, are SD/FO (combined). The state now has 773 total interstate and state bridges, and 301 – 39 percent – of them are combined SD/FO. Both of these percentages remain unchanged from 2010. On the municipal level, 37 percent, or 148 of Hawaii’s 403 total city/county/township bridges meet the classification for SD/FO (combined). This is a 1-percent increase from 2010, when 147 of the state’s municipal bridges met this definition.

New York State holds down the fourth-place spot for the highest percentage of total combined SD/FO bridges. At 37 percent, 6,405 of the Empire State’s 17,421 total bridges are considered SD/FO combined. In 2010, 37 percent of the state’s then total 17,405 bridges were SD/FO combined.

Breaking down the numbers, 39 percent, or 3,227 of the states total 8,344 interstate and state bridges are SD/FO (combined). This percentage is also the same as last year when New York had 8,335 total interstate and state bridges, nine fewer than this year, and 3,215 of the bridges met the combined SD/FO classification. In terms of city/county/township bridges, 35 percent, or 3,178 of the total 9,077 city/county/township bridges are SD/FO. Last year, 36 percent – 3,230 – of New York’s total city/county/township bridges were SD/FO (combined).

The fifth-highest percentage of overall combined SD/FO combined bridges is a tie between Connecticut and Pennsylvania, with both states reporting 36 percent of their total bridges in SD/FO condition. Last year, Connecticut was tied with West Virginia for the sixth-highest percentage of overall SD/FO bridges, with 36 percent of both state’s total bridges in SD/FO condition. West Virginia does make one list, though. It has the highest total of city/count/township bridges – 68 percent — in combined SD/FO condition.

In Connecticut, 1,502 of the state’s total 4,184 bridges were considered SD/FO (combined). For Pennsylvania, of the state’s 23,587 total bridges, 8,524 are a SD/FO combined. Despite the same overall SD/FO percentage for total number of bridges, the similarities end there. Connecticut has 37 percent – 1,079 – of its total 2,941 state and interstate bridges considered as a combined SD/FO. When ranking the states by the highest percentage of total interstate/state bridges, Connecticut comes in fourth. Total city/county/township bridges considered SD/FO (combined) are 34 percent, specifically 423 of the 1,243 total city/county/township bridges. These numbers do not put Connecticut on the short list of highest percentage of total city/county/township bridges.

Pennsylvania has 32 percent – 5,335 – of its total 16,729 total interstate and state bridges considered SD/FO. However, nearly one-half – 47 percent – of the 6,858 total city/county/township bridges are SD/FO combined.

Fixes and Wish Lists

If I could change just one thing . . .

It’s a poignant question that we asked agencies: If you could change any one aspect about your department to improve your bridges, what would it be?

Douglas E. Finney, bridge management engineer for the Delaware Department of Transportation, says he’d like to see more of an emphasis placed on maintenance, “to correct more problems before the bridge becomes deficient.” Despite hopes for a greater stress on preventive maintenance, the state has still managed to reduce its number of overall SD/FO bridges (combined). Delaware has reduced its total SD/FO (combined) interstate and state bridges from 171 in 2010 to 167 this year, also bringing its combined total number of SD/FO combined city/county/township bridges from 175 in 2010 to 171 this year.

Georgia Department of Transportation State Bridge Maintenance Engineer Mike Clements would also like to see a stronger maintenance focus. “Add more bridge maintenance positions and increase bridge maintenance funding,” Clements proposes. “Both of these have been decreasing over the last 10 years.” But he also boldly suggests that “bridge maintenance funding should increase and new roadway funding [should be] decreased.”

Washington, D.C.’s Cooney advocates that “a greater emphasis on preventive maintenance” is one of the major overhauls that is needed to the system of planning, building and maintaining bridges in the United States at the federal, state and local levels.

Bridge engineers at the Virginia Department of Transportation (VDOT) agree. Not only is “more funding needed at national, state and local levels to address bridge needs,” but greater emphasis needs to be placed on system preservation and preventive maintenance, “to maintain structures in good condition and to slow the downward trend of structures moving into the deficient category, while at the same time addressing the deficient bridge population,” say Claude Napier and Adam Matteo, VDOT engineers responsible for bridge safety inspection and bridge maintenance, respectively.

Matteo and Napier suggest that states use high-performance concrete, high-performance steel, corrosion-resistant reinforcing steel and other high-performance material to “extend the service life of new structures as well as those that are being rehabilitated.” They also say agencies should consider jointless construction for new construction of integral or semi-integral and continuous spans, as well as the elimination of deck joints on existing bridges. “Leaking joints are a major cause of deterioration to superstructure and substructure elements beneath leaking deck expansion joints,” Napier and Matteo explain. “The use of accelerated bridge construction techniques and prefabricated bridge elements should be considered and used to minimize the impact on the traveling public.”

Additionally, they say, a systematic approach should be used for addressing bridge needs through preventive maintenance, restorative maintenance, rehabilitation and replacement, which are funded through maintenance funding and dedicated bridge funding. “A new emphasis is [also] being placed on rural bridges and culverts using Stimulus funds,” say Napier and Matteo.

Harvey L. Coffman, bridge preservation engineer for the Washington (State) Department of Transportation, proposes that the “use of preventive maintenance funds should be allowed for structurally deficient bridges.” W. Kyle Stollings, director of West Virginia Department of Transportation’s Maintenance Division, adds that complete designer control of quality assurance/quality control and serviceability is needed in contract documents. “Serviceability/lifecycle costs [are] compromised due to first cost issues.”

Alex Bardow, bridge engineer for the Massachusetts Department of Transportation, says that “streamlining environmental process, public participation and ensuring dedicated bridge preservation funding” is also greatly needed.

When it comes to financing and repairing/replacing bridges in the United States, a one-size-fits-all approach shouldn’t be used, says South Dakota DOT’s Olson. “I live in a rural state, and sometimes we’re just following procedures because it’s regulatory everywhere.” This means, he says, that just because the federal government adheres to a certain procedure, it wants everywhere else to follow it, but it doesn’t always make sense financially or isn’t necessary. The funds used to follow the procedures could be better spent elsewhere, such as repairing or replacing bridges, Olson says.

John Clark, senior bridge maintenance and repair engineer for the Florida Department of Transportation, calls situations such as Olson’s “unfunded mandates.” Clark says the primary responsibility at the federal level is the interstate system. However, because funding starts at this level and because of organizations such as AASHTO, sometimes mandates trickle down to the states and even local bridges off the interstate system.

“They hold captive funding for the interstate by saying, ‘We’d like you to do something this way,’ but it’s essentially an unfunded mandate,” Clark explains. “We then have to do certain things we weren’t expecting to do and we’re not being funded for it. Their [federal] vision is from a national standpoint, which may or may not align with the state’s vision for the transportation system.” When the visions do differ, Clark says, “it can cause us to spend money that we think is not helpful or is unnecessary. As long as the DOT management accepts it, though, it’s what we go along with. But it is something I would look at.”

Keeping this in mind, it’s notable that Florida makes the short list of states with the lowest percentage (No. 7, 17 percent) of SD/FO combined bridges. “We have a statute in Florida that if a bridge becomes structurally deficient or ‘posted,’ it must be repaired or replaced within six years to remove the deficiency,” Clark points out. “We don’t have a lot of mandates, but that is one of them. That is one reason we have a low number of SD bridges. The government has decided that transportation is a key element of our economy, so it puts resources there.”

Jeff C. Vigil, P.E., state bridge management engineer for New Mexico’s Department of Transportation’s Bridge Maintenance Unit, says that states need “stable funding sources” to remove the uncertainty that is currently dealt with when planning for the future. At his department, design and construction funding levels for FY 2011 were up slightly to about $500 million. “This amount is expected to drop by about 30 percent for FY 2012,” he says.

Utah’s Department of Transportation (UDOT) says it hopes to be able to lower its rate of deficient bridges in the coming year, but it all depends on funding. To what extent will insufficient funding restrict important work for UDOT in the coming year? “This remains to be seen,” says Daniel Page, UDOT bridge design and operations manager.

Bruce Johnson, bridge engineer with the Oregon Department of Transportation, believes that insufficient funding will restrict important work next year to “a great extent.” Although the agency expects to lower its rate of SD/FO bridges in the coming year through a bonding program, the bridge program “is decreasing due to a reduction in funding.”

The Kansas Department of Transportation also expects to lower its rate of deficient bridges in the coming year, “through continued funding of the T-works program [a comprehensive transportation bill that was passed in the 2010 state legislative session] and a focus on preservation of our current system,” says Calvin Reed, bridge management engineer for KDOT Bureau of Transportation Planning. “State funding is fairly secure, [but] federal funding is up in the air. If federal funding drops, some work will have to be postponed.” Modifying the current system of receiving federal funding would help with this problem. “The sufficiency formula is outdated.”

The Mississippi Department of Transportation’s bridge replacement program has benefited from an infusion of 100-percent state funds, which the agency says will help it reduce SD/FO bridges. “This has allowed us to continue to lower the number of deficient bridges,” MissDOT’s Carr explains. That being said, Carr notes “once the temporary infusion of state funds has been expended, we will once again only have our normal level of federal bridge replacement funds.” Right now, Carr says, “the most urgent need is increasing the level of federal bridge replacement funding. Federal bridge replacement funding has remained generally the same for over 20 years. In that same time, construction costs have more than doubled. Increased federal funding is imperative.”

Q&A:

Describe the past 12 months for your department in terms of work and funding.

“Work needs have increased while funding has decreased.” –Eric J. Christie, assistant state maintenance engineer for bridges, Alabama Department of Transportation

“We have performed a significant amount of work on culverts that are too small to be included in the [Better Roads] National Bridge Inventory.”—Douglas E. Finney, bridge manager engineer, Delaware Department of Transportation

Q&A:

To what extent will insufficient funding restrict important work in the coming year?

“Federal funding uncertainties may result in withholding projects.” –Harvey L. Coffman, P.E., bridge preservation engineer, Washington (State) Department of Transportation

“Projects [may be] deferred due to flat revenues.” – W. Kyle Stollings, director of Maintenance Division, West Virginia Department of Transportation

What We Do

The Bridge Inventory is an annual survey begun in 1979. Bridge engineers from each state and Washington, D.C., are sent a survey with both qualitative and quantitative questions.

How deficient and obsolete bridges break out in 2011 -- States and the District of Columbia have provided separate counts for the latest numbers on the breakdown of their structurally deficient (SD) and functionally obsolete (FO) bridges. For the FHWA’s explanation of what makes a bridge structurally deficient and how a bridge becomes functionally obsolete, go to http://www.fhwa.dot.gov/policy/2008cpr/chap3.htm#7. Better Roads’ editorial staff would like to thank all the state highway engineers for their continuing cooperation and special effort to provide current data. The data was collected through November 2011.

Q&A:

Do environmental restrictions affect how well you can replace or repair deficient bridges?

Yes

Jeff C. Vigil, P.E., state bridge management engineer, New Mexico Department of Transportation: “Yes. Environmental restrictions and restrictions due to historical classification of bridges cause delays to our bridge projects.”

Benjamin W. Foster, assistant bridge maintenance engineer, Maine Department of Transportation: “Yes. [It] increases construction costs.”

Mike Clements, state bridge engineer, Georgia Department of Transportation: “Yes. Environmental documents increase the time from concept to letting.”

Thomas Martin, bridge maintenance engineer of Minnesota Bridges and Structures: “Yes. Project time span and costs are increased due to environmental restrictions and compliance.”

Bruce Johnson, bridge engineer, Oregon Department of Transportation: “Yes. [It] adds cost and delays.”

Steve Andersen, Nebraska Department of Roads, Bridge Division: “Yes. The environmental process has become so lengthy, it takes three years to get a project through to a letting.”

Michael B. Johnson, office chief, California Department of Transportation: “Yes. Some permits are difficult to get in a timely manner.”

NO

Claude Napier, bridge safety inspection, Virginia Department of Transportation (VDOT), and Adam Matteo, bridge maintenance, VDOT: “No. We are able to work through environmental challenges (in-stream restrictions, endangered species, wetlands and any hazard materials) through proper planning and early coordination. Environmental restrictions may affect project durations, but does not affect the quality of the project.”

Charles P. Brand, bridge engineer, Arkansas State Highway Transportation Department: “No.”

Eric J. Christie, assistant maintenance engineer – bridges, Alabama Department of Transportation: “No. Not generally, but [it’s] becoming more of an issue.”

Travis McDaniel, bridge engineer, Wisconsin Department of Transportation: “No.”

Ray Mumphrey, bridge engineer manager, Louisiana Department of Transportation; ‘No. [It restricts] progress.”

When a historical bridge in Maine had to be demolished and rebuilt, the question was how to do it and still preserve a landmark

By Tina Grady Barbaccia

When the historical bridge in Norridgewock, Maine, had deteriorated to a point where it had to be either demolished or rehabilitated, a delicate situation presented itself. The “concrete bridge” as the locals called it was part of the community’s character and charm — and part of the town’s emblem. No one wanted to see it razed, but the bridge needed to provide a safe and efficient river crossing. This made for a very sensitive situation, but one that was able to be worked out. The bridge opened to traffic this summer.

The design needed to be “both contemporary and fitting for the setting and the history of the site,” according to Wayne Frankhauser, project manager for the covered project. The challenge was clear: A bridge had to be designed in a way that was similar to the existing structure but incorporating as many modern design and construction techniques as possible.

The new Norridgewock bridge in Maine is the first modern concrete tied-arch bridge built on the East Coast in 50 years.

Complicating plans further was the fact that the bridge would be built with federal and state money. The Federal Highway Administration (FHWA) and Maine Department of Transportation (MaineDOT) would have to agree on a plan. Because of the historic significance of the bridge and historic buildings close to it, federal law requires that the Maine Historic Preservation Commission also had to be in agreement, according to MaineDOT. After conducting a study from 1998 to 2004 to evaluate four crossings — both east and west of the current covered bridge — MaineDOT and FHWA came to the conclusion that although rehabilitating the bridge was an option, it was recommended that the current bridge be removed “due to its poor condition, narrow width and outdated height.” A new bridge would be built on the site.

Creating a Worthy Landmark

In 2004, the FHWA, MaineDOT and the Maine Historic Preservation Commission came to an agreement on the bridge’s design plan in a document known as a Section 4F statement. (See “Norridgewock Bridge Project Unique Stipulations” sidebar.)

The Kennebec River Bridge prior to demolition. It was an eight-span bridge that included four 100-foot tied-arch spans.

After all the stakeholders in the project had come to an agreement on the bridge design selected, they engaged the community with both a public meeting and an informal survey. When asked their preference about the two design options, the response was divided, with neither design being a clear winner.

The plans began to move forward. “Though we know [the] decision won’t please everyone, it’s time to move forward with construction plans,” Frankhauser said after the selection of the bridge design. Earle G. Shettleworth Jr., director of the Maine State Historic Preservation, fully supports the design decision.

He notes that the covered bridge in the current condition is “a bold statement of the modern age . . . one of Maine’s most significant 20th-century bridges.” However, with the two options that met the project’s purpose and need, “one embellishes what is otherwise a fairly standard girder bridge,” Shettleworth says. “The second uses a 300-foot center-arch span employing the latest design concepts. I firmly believe that the arch option is the only one that will result in a bridge [with a] design both functional and noteworthy, creating in the process a 21st-century engineering landmark worthy of this historic crossing.”

Combining Yesterday, Today and Tomorrow

When the bridge was first constructed in 1870, it was built as a 538-foot-long bridge with an arched portal and a gambrel roof. Laminated wooden trusses were later added to the inside of the bridge to increase the capacity. The 1870 bridge was lost to a flood and replaced in 1928. The 1928 structure was an eight-span, 600-foot-long bridge with four 100-foot concrete tied-arch spans and four concrete T-beam approach spans, considered one of the most advanced designs of the time.

The contractor is placing the concrete for the arch rib for the new bridge. Note the two in-water piers and the NEBT approach span that have already been completed along with the falsework.

Now, the historic structure is again incorporating some of the latest in bridge design technology. A 300-foot concrete tied-arch with New England Bulb Tee (NEBT) approach spans was chosen for the design as the preferred alternative, to minimize substructure cost while mitigating for the loss of the existing historic concrete tied-arch structure.

The concrete tied-arch for the new $21-million bridge is the first modern concrete tied-arch — to the best of all the stakeholders involved in the bridge’s knowledge – built on the East Coast in the past 50 years, says Keith Wood, P.E., senior project engineer for Kleinfelder|SEA, the consultant to MaineDOT on the project and the firm that conducted the preliminary study and the final design on the chosen bridge site.

“The overall depth of the girder bridges is constrained at the site due to the impacts they create on the surrounding historic properties,” Wood says. “The use of the tied-arch structure allows us to increase the span without increasing the depth of the superstructures, compared to the conventional beam option. We minimized the cost by reducing the number of piers required from four for a conventional beam girder bridge to two with the use of the long-span tied arch.”

Building a Better Bridge

In a traditional arch structure, Wood says, the bedrock supporting the foundation resists both vertical load and horizontal thrusts from the arch. As with the original bridge in Norridgewock, because bedrock is about 25 to 50 feet below the riverbed, a tied-arch structure was used to transfer only vertical loads to substructure units.

The contractor places the concrete for the tie girder, the member that holds the ends of the arch together.

The tie girder, which uses conventional post-tensioning technology, ties both ends of the arch together, counteracting the thrust forces from the arch, Wood explains. At each end of the tie girder, a large concrete section serves as an anchorage block for the post-tensioning system and to connect the tie girder to the arch rib. Within the tie girder, eight post-tensioning ducts each carry 27 post-tensioning strands. The strands in the post-tensioning ducts are stressed and grouted — as is required in the specified construction sequence — to resist the thrust of the arch rib, Wood says.

The construction sequence itself is quite unique. Because of the bridge location, the construction team had to expedite the bridge building process so it was complete in one construction season. “The bridge is over the Kennebec River, which is known to have severe ice conditions, especially during the spring melt,” Wood points out. “We didn’t have a lot of time due to the ice conditions, so we had to develop a construction sequence for one construction season.”

Because a tied-arch structure cannot act as a fully-functional bridge until it is essentially complete, a construction sequence was developed to allow the arch to function prior to completion, Wood explains. “The use of precast floor beams, a staged post tensioning sequence, and placement of the diaphragms and deck after the removal of falsework were used to reduce the construction time,” he says. “We had to be able to build the bridge in a year.”

The project began in late summer 2008, when a temporary bridge structure was built parallel to the existing bridge. After completion of the substructures and the two approach spans in the spring of 2010, six temporary piers were put on each side of the actual bridge to hold it up. Falsework was placed on top of it, and then the floor beams, which were precast offsite, were laid out in place. “By pre-casting the floor beams offsite as opposed to casting onsite, it reduces the construction time tremendously” Wood explains.

Both the temporary falsework supporting the girder and the precast floor beams were part of the innovative construction sequence to allow the bridge to be built in one year.

Following the installation of floor beams, the construction team cast the end beams, arch-end connections and the tie girder, and the first phase of post-tensioning was put in place. Additional falsework was constructed and then the arches and transverse struts were built. After the removal of the falswork for the arch ribs and the transverse struts, hangers were installed, and the tie girder falsework was lowered place, which then allowed the bridge to operate as an actual structure.

The bridge had just opened to traffic. Full completion of paving and the finishing touches on the arches are to be done this fall.

At-a-Glance

Total length: 567 feet

Spans: 300-foot tied-arch span in center with two 128.5 New England Bulb Tee (NEBT) spans on either end

Arch: 60-feet high at the center

Hangers: 18 sets of hangers — nine per side, two at each location

Travel lanes and use: Carries two 12-foot travel lanes with a 6-foot shoulder and 5-foot sidewalk on one side of the road; on the other side is a 4-foot shoulder and 7-foot multi-use lane for snowmobiles in the winter and horses, bicycles, etc., in the summer

Norridgewock Bridge Project Unique Stipulations

Due to the historical nature of the Norridgewock Bridge Project, the bridge’s design had the following unique stipulations that had to be met, according to MaineDOT:

• Document the covered bridge in accordance with Historic American Engineering Record standards.

• Incorporate design features that are appropriate to the setting, through continued consultation with Maine Historic Preservations Commission.

• Design the replacement bridge in a collaborative process that includes Federal Highway Administration, MaineDOT, Maine Historic Preservation Commission and the town of Norridgewock. This team is called the “Signatories Committee.”

• Produce a design that is both contemporary and fitting for the setting and the history of the site, by seeking ways to:

° visually enhance the setting,

° reflect its history,

° maintain compatibility with the character of adjacent historic properties, and

° prudently use transportation funds.

• Erect a plaque and/or interpretive panel(s) depicting the covered bridge, its history and its significance at a location near the site of the bridge.

• Produce a model/diorama depicting the history of river crossings in Norridgewock.

• Publish an illustrated booklet documenting the transportation history of the Norridgewock area.

Source: MaineDOT

Buy a Border Bridge!

No Money Down

Cash-squeezed Michigan plans a new Detroit River crossing to Canada with ‘no risk’ to its weary taxpayers

By Mike Anderson

Officially, the long-running project to eventually build a new cross-border bridge in southeast Michigan is identified as the Detroit River International Crossing – or DRIC.

For those truckers who have idled for hours on or in front of the venerable Ambassador Bridge, deadlines running out for their just-in-time loads of new auto components, the experiences at the Detroit-Windsor crossing are more like DRIP… DRIP… DRIP – as in, “Friend, you aren’t going anywhere fast.”

For the past decade, through the ups and downs of public meetings, environmental reviews, funding dilemmas and political grandstanding (all times two since what happens on one side of the river must essentially be replicated on the other), it’s that one fact – the wait – that prevails.

Well, wait not too much longer, if the new State of Michigan Administration under Republican Gov. Rick Snyder has its way. “We’re looking at the overall need to create an environment in Michigan conducive to job growth,” explains Lt. Gov. Brian Calley. “There really is just a critical need to make that freeway-to-freeway connection. We think that southeast Michigan, this particular corridor, has an opportunity to be a major international intermodal transportation hub.”

The rail crossing is in place, as is a major international airport a little further west, he says, but the key to future prosperity is relieving the ground transportation bottleneck via a new downriver crossing, directly linking to Interstate 75 south of Detroit and Highway 401 across the creek in Windsor, Ontario., providing additional access to not only Michigan’s major trading partner, but to Canadian ports positioned to relieve the overcrowding at U.S. docks. The Ambassador Bridge, first opened in 1929, is today the busiest North American border crossing and yet traffic flow often remains a mere trickle, damming the heavy flow of cross-border trade that is reflective of the continent’s modern-day manufacturing structure.

Most of the $43 billion in trade between Michigan and Ontario travels over this privately-owned bridge; the nearby Detroit-Windsor Tunnel is jointly owned by the two cities and is for local core-to-core traffic, mostly cars. The recent Gateway Project on the U.S. side has, as Lt. Governor Calley admits, somewhat improved flow from the Ambassador Bridge to I-75; the Canadian side remains an urban tangle, in which all vehicles to and from the bridge must drive along a city street, in front of homes and businesses, for about 8 miles.

The Snyder Administration, with Calley, also the State Senate President, as its lead on the border file, is pushing a Michigan bill that would set in place a structure under which “private-sector” construction and management would proceed on what would be an additional bridge owned bilaterally by the neighboring nations. “Previous attempts have essentially ignored the project itself and instead authorized an administrative department to enter into any public-private partnership that didn’t require a state appropriation – very, very broad authority that the previous administration tried to award the Department of Transportation. That’s not the sort of thing that the folks over in the legislature would normally be interested in accommodating,” Calley says during a face-to-face interview with Better Roads in his downtown Lansing office, acknowledging the imposing Italianate State Capitol building over his shoulder.

“What we’re proposing is authorization to go forward with ‘A’ project in ‘A’ location – a specific legislative authority.”

How Would It Work?

Under Governor Snyder’s proposal, Michigan would establish a new governmental authority for international trade crossings, not unlike the intra-state authority that operates the majestic, suspension Mackinac Bridge linking Michigan’s Lower and Upper Peninsula, says Calley. The new international crossings authority would form a joint venture with its Canadian equivalent that would not actually build the new $1-billion Detroit River bridge, but rather draft a concessionaire agreement that would lay out specifications for both the bridge’s construction phase and its ongoing management for a period of up to 50 years. The international joint venture would put the project out to bid, and then choose a private partner to secure financing to design, build and operate the crossing that would remain owned, as is the norm, 50-50 by the U.S. and Canadian authorities.

“It is a true private-sector project,” says Calley, challenging the criticisms of Ambassador Bridge owner Manuel “Matty” Moroun, whose Detroit International Bridge Company would like to build a second span at its site and has waged a public-relations campaign against Governor Snyder’s proposal (and a preceding legal fight against governments on both sides of the border). “The difference between this and the other, hypothetical alternative is that the hypothetical alternative, the twinning of the Ambassador Bridge, essentially grants a monopoly in a no-bid situation,” says Calley. “We’re interested in putting the power of the market behind this project. We’d be happy for the Ambassador Bridge folks to bid on this project – they’d be free to do so like everybody else – but they wouldn’t get a government-endorsed monopoly. It would be something they’d have to compete for and win.”

Bridge revenues moving forward would provide the security for the new crossing’s developer, says Calley. “The State of Michigan would not be required to either directly take on debt or indirectly guarantee any debt,” he says. “This is purely a private-sector risk, and the private sector will have to make a determination on its own: ‘Is the risk worth it?’ That’s an excellent check-and-balance in the proposal.” Interested private-sector parties would still have to conclude whether traffic patterns and international trade growth potential could support the project, “but trends make it a pretty easy answer to say, ‘Yes.”’

History Repeats . . . Sort Of

But what good is a new bridge, even one paid for by someone else, if the budget-strained State of Michigan can’t come up with the dollars for the construction necessary to accommodate the bridge? Without an I-75 interchange and border plaza, even the greatest structure known to mankind would be rendered useless.

Well, thankfully for the folks at the State Capitol in Lansing, there’s a rainbow that extends a couple of hours east into Canada. Authorities in the neighboring country will loan up to $550 million for the Michigan-side improvements, “to the joint venture itself, not to the state,” says Calley.

“And this is not without precedent. Back when the first Bluewater Bridge was built (at the mouth of Lake Huron, linking Port Huron to Sarnia), the roles were reversed. Michigan was interested in having a crossing at that location, the Canadians didn’t have the money to do it, and so Michigan fronted the money. And the tolls from the Bluewater paid back Michigan.

“It would be the same thing this time: The tolls after the developer is paid go to pay Canada for the Michigan-side improvements to connect the bridge.”

Calley emphatically challenges the suggestion that this arrangement would provide an unfair advantage to any new competitor in the Detroit-Windsor crossing market. “We, the taxpayers of the State of Michigan, spent hundreds of millions of dollars on an I-75 rebuild, redesign and interchange for the Ambassador Bridge,” he says. “The only difference between our project and their project is that the Michigan taxpayers subsidized the Ambassador Bridge owners to connect their bridge and Michigan taxpayers won’t have to subsidize the new bridge.”

Despite the freshness of the Snyder Administration, elected this past November and inaugurated on New Year’s Day, there’s clearly murky water under the bridge when it comes to the feelings about the Ambassador and its staunch 84-year-old owner, Moroun, who bought the iconic structure in the late 1970s. The Detroit-Windsor Bridge is the only privately-owned border crossing between the U.S. and Canada. Even that shiny new Michigan-side Gateway Project has left controversy, “because the bridge company contracted by the state reneged on the contract and put a gas station in the middle of the plaza, creating a new bottleneck,” says Lt. Governor Calley. That will, he says, be rectified through court action. “In the meantime, Michigan employers suffer yet again at the hands of the bridge company owners.”

Pay It Forward?

If and when Governor Snyder’s plan receives authorization from the Michigan legislature – “and people across the street have been willing to look at this proposal with a fresh set of eyes,” says Calley – obtaining the Presidential Permit for the border crossing should not pose a problem. “The Obama Administration has made it clear that expanding exports over the next 10 years is a priority.”

The go-ahead won’t, says Calley, be the only benefit coming out of The District for Michigan. The Great Lakes State’s gas tax revenue is declining to the point that, he says, next year the state is projected to leave federal matching dollars on the table. However, when the proposed joint venture with the Canadian authority spends the funds required for the Michigan-side interchange and plaza projects to accommodate a new border crossing, it will count as the state spending on federal-qualified roads, securing the federal match moving forward and drawing down about $2.2 billion for road-and-bridge projects throughout the state. “With the gas tax, we have been a donor state forever,” says Calley, “and now is the time to close that gap.”

On the Michigan side, construction jobs during the actual bridge project would total about 10,000, he says, but the longer-term effect of an expanded international logistics hub is exactly the type of foundational restructuring the region needs. “It makes a statement about southeast Michigan, and Detroit in particular. Our goal is to set Detroit on a different path, a path to success. We believe in the future of this state and we believe in the future of Detroit with the proper leadership,” he says, “and this project will be a real boost.”

Beyond there, “I’m truly excited about the prospect of Michigan actually taking a piece of the benefits from global trade. Over the years, we have been more of a victim than a beneficiary of such things,” says Calley. “This really gives us an opportunity to profit from, to benefit from, to grow jobs from international trade, reversing this trend that we’d seen in the last generation.”

A bridge to the future, if you like.

Crossing Over:

Little Time to Wait

Michigan Lt. Gov. Brian Calley talks passionately about the global opportunities a new Detroit River International Crossing (DRIC) could create for his state. But, he is quick to remind, this is also a local issue.

Indeed, to truly comprehend what border crossings mean to the immediate populace is to understand that people on one side of a river will line up every single day just to head off to work, to shop, to socialize, to even just go to a ball game on the other side. They may be from different countries, with different cultures, but there is a common community for folks on both sides.

In southeast Michigan, for instance, there is such a nursing shortage that hundreds of nurses drive across from the Windsor side every single day, says Calley. A massive snowstorm last winter shut down Highway 402, the Canadian freeway that runs to the Bluewater Bridge at Sarnia-Port Huron, shifting even more truck traffic than normal further south to the Ambassador Bridge and thus heavily backlogging the crossings in the Detroit-Windsor area. Hospitals in Michigan depending on the 24-hour care provided by nurses were left in a near-crisis situation as many of those nurses sat snarled in traffic.

The same storm caused a U.S. auto plant to temporarily shut down – its production parts stuck at the border. “That’s a big deal,” says Calley. “The impact of these crossings is far and wide. Our economies are so intertwined that as far as I’m concerned there’s not an interest for Michigan that is substantively different than the interest Windsor and really that whole side of the bridge has. Our destinies are tied together.”

One in eight jobs in the immediate southeast Michigan region depends on trade with Canada, and incredibly that rate jumps to one in seven a few hours away in western Michigan. A new bridge will not only secure future growth by removing a trade barrier, says Calley, but will protect the 230,000 current jobs in the state that depend on cross-border trade. “We’re in a very risky situation where we have one bridge that handles so much of that now. If there was anything that even for a short period of time shuts down the Ambassador Bridge, there would be a catastrophic economic collapse.

“I don’t think you could overstate how dramatic the impact would be on the Michigan economy.”

A sharp decline in bat numbers prompts Oregon’s Department of Transporation to build habitats into bridges.

By Tina Grady Barbaccia

Build a bridge, save a bat.

That’s what the Oregon Department of Transportation (ODOT) has done as part of its Oregon Transportation Investment Act (OTIA III) State Bridge Delivery Program, a 10-year, $1.3-billion program that is repairing and replacing hundreds of bridges across the state.

Colonies of Townsend’s big-eared bats such as these are exactly the sort of residents the Oregon Department of Transportation hopes to lure to its newly rebuilt Curtis Creek Bridge.

Knowing that bat numbers in the United States have fallen sharply since the 1960s, ODOT proactively incorporated bat habitats on bridge projects to promote roosting. Included in these measures was the development of an outcome-based Bat Habitat Enhancement environmental performance standard (EPS).

Aware of what a laborious process it could be to obtain permits for each bridge separately, ODOT initiated a program — environmental programmatic permitting — that incorporated both state and federal partners, which served as the process that brought together myriad agencies under one permit. This captured regulatory commitments on a program level versus a project level. The state and federal partners together formed the Programmatic Agreements Reporting and Implementation Team, or PARIT. The team met regularly to resolve any challenges and discuss common goals. This not only sped up the bridge permitting process, but it allowed the team to develop other innovations under the same programmatic such as wildlife passages and the Fluvial Performance Standard (go to www.obdp.org/partner/environmental/performance/ for more information) — enhancements that may have been otherwise overlooked.

This photo was taken looking up toward the cave-type habitat on the Curtis Creek Bridge, constructed between two girders near the diaphragm on top of the supporting piles and pile cap. The bottom flange of the girders supports the floor of the bat habitat and a cutoff wall is constructed on top of this floor to create the cave. Access to inspect the pile cap and diaphragm is created on the opposite end of the cutoff wall.

The normal standalone project delivery process includes a biological opinion, and then an assessment that must be processed through each agency. “It can be a complicated, time-consuming process just to get everything lined up for one site,” says Geoff Crook, environmental manager for the OTIA III Bridge Delivery Unit. “Regulations are often prescriptive and define what you can and cannot do in a quantitative way. However, instead of having many permits with many agencies, a programmatic batches everything together. Our solution was to take a collaborative approach to deliver the program. Focusing on areas of mutual agreement — e.g., safety, economic development, efficiency and environmental stewardship — we developed a single set of environmental performance standards that meets the intent of all the contributing agencies’ regulations while allowing contractors maximum flexibility in how they achieved them.”

This allowed the biological opinion to be batched together to make everything eligible under one permit. The formation of a multi-agency PARIT team also allowed ODOT quick access to decision makers, which allows for quicker responses times and flexibility during design and construction.

Two cave-type habitats for bats can be seen in the center and far left of this photo.

“That is efficiency in and of itself,” Crook says. The streamlined process was also cost-effective. In a cost-benefit analysis of the return on investment for programmatic permitting in terms of cost avoided, return on investment (ROI) was $3.19 for every $1 spent, according to Crook. Using a traditional permitting approach, the ROI was 75 cents for every $1 spent. What’s more, the efficiency of putting together a programmatic permitting process enabled ODOT to wrap up the environmental portion of the 10-year bridge program this past fall. Originally set for completion in 2013, the environmental programmatic permitting team wrapped up its work in only seven years. By some estimates, it would have taken 50 years to permit all the bridges — nearly as long as the 75-year expected lifespan for the structures themselves — if the traditional permitting process was used.

One program, multiple agencies

In the development of environmental programmatic permitting, performance standards of multiple regulatory agencies were synthesized to satisfy multiple requirements under one permit.

The floor of a bat habitat and the bottom of the cutoff wall can be seen.

Included in the programmatic permit were standards for bat habitats. “We’d like to do something for the uplift of the species,” Crook says.

Bats are not a regulated species in Oregon, although in some states they are “endangered” or “threatened.” But bat numbers have been declining, so when the programmatic permit was being developed, ODOT worked with the Oregon Department of Fish and Wildlife and the U.S. Department of Fish and Wildlife to develop standards that could be rolled into the programmatic. The standard outlines a goal — to maintain, replace or improve roosting on bridges over waterways. This standard was only developed for bridges over waterways because this is where bats’ primary food source is.

ODOT wants to keep bridges bat-friendly because of the integral role the mammals play in the environment. In a single night, one bat may eat thousands of insects, including mosquitoes, which could carry West Nile virus, Crook says. Some bat species also serve as pollinators whose eating habits can help farmers reduce pesticide use, he adds.

“The Oregon Department of Transportation wants to keep bridges bat-friendly because of this beneficial role in the ‘web of life,’” Crook points out.

However, contemporary precast concrete structures lack the texture and crevices bats need to be able to roost, so ODOT biologists worked with their counterparts from the Oregon Department of Fish and Wildlife and the U.S. Forest Service to develop guidelines that help engineers design bridges with bats in mind. Instead of forcing existing populations of bats to relocate, ODOT integrates habitats into the bridge structures when they are rebuilt or adds them on in the form of bat boxes when a bridge is being repaired instead of being replaced.

“We developed plans to actually build bat habitats into the bridges,” Crook says. “As bridge designers are looking at bridge constraints and what kind of structure or material to use, they will consider incorporating a bat habitat. An integrated bat habitat is highly beneficial because it doesn’t need maintenance like wood does.”

The performance standard provides clear guidance to bridge designers about how to replace, maintain or improve suitable roosting habitats on bridge program projects, according to ODOT.

ODOT worked with regulatory agencies to identify which bats may or may not be on the bridge at the time of the bridge assessments by looking for current habitat use and whether the bridge could be used with slight additions or alterations. Biologists went out into the field with a flashlight at night to check the bridges for bat use and to identify which species were using the bridges, because this would impact the type of structure that would have to be incorporated into the bridge design or rehabilitation plans. “We developed plans to build bat habitats into the bridges themselves,” Crook says. “This walks the designer through what to consider. We are essentially building habitats for different bat species.”

A place to call home

At Better Roads press time, 88 bridges in the program were in compliance with bat habitation environmental performance standards, according to ODOT. The agency has verified that its bat habitats have been successful.

With the creation of a crevice habitat — one of three types of bat habitats on bridge structures — in the shallow box-beam bridge replacements to provide a roost for mouse-eared bats, inspectors found piles of guano, or bat waste, directly beneath the crevices shortly after construction. This served as evidence that bats were using the structures, the agency says.

The other two types of bat habitats that can be incorporated into a bridge include a cave-like or an “Oregon wedge” design.

With a crevice habitat, an integrated habitat is built into the concrete of the structure. This is a crevice type of habitat that incorporates box-beam girders or pre-cast concrete. A gap is placed between the boxes to provide a crevice that runs along the span of the bridge. “We can size the crevice appropriately for an ideal bat habitat,” Crook says, adding that 1/2 inch to 1-1/2 inches is standard for the crevice.

A cave-like, or cavernous habitat, is idea for the brown bat. An actual box is built into a span between box girders to provide an open area. The “Oregon wedge” is a simple plywood box designed to accommodate hundreds of bats at a time. The vertical box is typically affixed to the side of a bridge with a 1/2-inch crack, so bats can crawl up inside of it.

“This gives them a place to shelter and roost,” Crook says. The box can be placed in a beam or on the outside of it. Placing it in a beam is advantageous because it is darker and there is less temperature swing. However, the advantage to placing the box on the southern outer side is the quicker heat up of the concrete during the winter.

Bats like to thermoregulate; they need to maintain a certain body temperature. “Even though they roost in the dark, they need heat,” Crook says. “They move up and down within structures, depending on the time of day, so they can use solar radiation.”

If it’s really hot out, bats will work their way down on the diaphragm or crossmember to get more air flow and cool down, explains Randy Reeve, a senior scientist for Parametrix. Reeve worked for the Oregon Department of Fish and Wildlife at the time the EPS was being developed. However, concrete is a good heat sink, meaning it takes a radical temperature change before the concrete loses or gains heat, so if it’s cold out, the bats will work their way up to the top of the structure where there is more concrete around them and less exposure to the wind.

In erecting the bat habitats, Reeve says, masonry board on plywood is being experimented with to give the bats a better grip. Additionally, when bats are hanging in their roost, they are naturally going to lose bodily fluids through urination and defecation, Reeve says. “If this is done on wood for an extended time frame, the wood will start to deteriorate,” he says. “But concrete, which deteriorates slower than plywood, will be there for a long period of time without the agency having to worry about it etching or deteriorating.”

In some cases, contractors have installed 80-grit sandpaper onto the plywood forms so the bats have a nicely textured surface to grip during the roosting.

These bat habitat additions are just minor considerations in the design of a bridge, notes ODOT’s Crook. “It doesn’t affect the overall structure of a bridge.”

According to Bat Conservation International, transportation departments are ideally positioned to help re-establish bat populations, Crook says.

“By identifying existing habitats and proactively building roosts during bridge construction, often for less time and money, states protect and encourage bat populations, which in turn, have a positive effect on the ecosystem,” Crook says. “Like the bridges themselves, many of the innovations in heavy highway construction will be invisible to most people. But as builders and designers and employees of government agencies work together and share what we know about new ways of doing business, we’ll all experience the difference in diversity in habitats and species, and in cleaner air and water.”

The status of programmatic permitting for OTIA III State Bridge Delivery Program projects through Feb. 28, 2011.

Rescoped as “No Work” — 94

Designed Prior to Completion of Programmatic Permitting Process — 54

Alternate Permitting Process — 11

Programmatic Permitting Complete — 206

A Team Effort

The Oregon Department of Transportation (ODOT) worked with partners to streamline the environmental permitting process by forming the Programmatic Agreements Reporting and Implementation Team (PARIT) including:

Oregon Departments of Fish and Wildlife, State Lands, Land Conservation and Development, and Environmental Quality;

U.S. Army Corps of Engineers;

National Marine Fisheries Service;

U.S. Department of Fish and Wildlife;

Federal Highway Administration (FHWA); and

U.S. Environmental Protection Agency (EPA).

Making a Difference

The National Partnership for Highway Quality (nphq.org) recognized the Oregon Department of Transportation (oregon.gov/ODOT/) with a Gold level 2010 Making a Difference Award for Partnering (nphq.org/awards_success.cfm/). ODOT received the honor because of strong collaborations with nine environmental regulatory agencies that helped it deliver on its commitment to avoid and minimize impacts as it repairs and replaces hundreds of aging highway bridges statewide.

ODOT’s success in environmental stewardship on the OTIA III State Bridge Delivery Program (oregon.gov/ODOT/HWY/OTIA/bridge_delivery.shtml) is due largely to early planning and coordination with its regulatory partners to design a programmatic permitting process.

Together, they developed a single set of standards that meets all the contributing agencies’ goals while allowing contractors maximum flexibility in how they achieve them. Many of ODOT’s successes in materials reuse and recycling, stewardship of species and habitats, and protection of water quality are the result of this collaborative, outcome-oriented approach.

ODOT worked with the Oregon Departments of Fish and Wildlife, State Lands, Land Conservation and Development, and Environmental Quality; U.S. Army Corps of Engineers; National Marine Fisheries Service; U.S. Department of Fish and Wildlife; Federal Highway Administration; and U.S. Environmental Protection Agency to streamline the programmatic permitting process. Through this effort, the partners have permitted all eligible projects – a total of 206 bridges – and will ultimately save the agency an estimated $73 million in costs avoided.

“ODOT and its team of partners knew that the only way to tackle this challenge was to work together for a solution,” says Tom Lauer, ODOT major projects branch manager. “The important relationships we’ve built through the bridge program will continue as we extend our commitment to protecting the environment on future transportation projects.”

Award recipients were judged on: their measurement of a high-quality result and customer focus; the originality and ingenuity of innovation; cooperation involved in innovation; implementation of innovation by the respective organization; and cost and time savings.

Integral Abutment Bridges

A survey on the status of use, problems and costs associated with integral abutment bridges

by Andreas Paraschos, P.E. and Amde M. Amde, P.E.

(For an unedited, downloadable PDF of the Integral Abutment Bridges article, click here. )

Integral abutment bridges provide an excellent alternative to conventional bridges built with bearings and expansion joints. Integral abutment bridges incur lower construction and maintenance costs compared to conventional bridges. In addition, they have a longer service life and a superior seismic performance compared to conventional bridges. Forty-one states are now using integral abutment bridges. Despite their wide acceptance by state transportation agencies and the engineering community in general, however, use of integral abutment bridges for long bridges and in situations that involve complex structural and soil conditions is still limited.

This article presents the findings of a survey conducted in 2009 by the University of Maryland at College Park that focuses on state integral abutment bridge practices. It summarizes the responses received from the states with regard to the status of use, problems and costs associated with the use of integral abutment bridges.

The Problem with Deck Joints

Early bridge structures were designed as a series of simply supported structures. With the introduction of the Moment Distribution Method in 1930, structural engineers began to design bridges as continuous structures. As a result, it became possible to construct longer bridges. Deck joints were provided in bridges in order to accommodate deck expansion and contraction without compromising the structural integrity of the bridges.

The introduction of deck joints created many problems to bridge owners. Joints are expensive to buy, install, maintain and repair. Repair costs are high. The joints leak throughout time, allowing deicing chemicals to attack the girder ends, bearings and supporting reinforced concrete substructures. The result is corrosion and deterioration of girders, bearings and substructure. Bearings are also expensive to buy and install, and are more costly to replace. Throughout time, steel bearings malfunction due to loss of lubrication or buildup of corrosion. Elastomeric bearings can split and rupture due to unanticipated movements. Because of these problems, it is necessary to continually inspect, maintain and periodically replace the joints. The use of expansion joints and bearings to accommodate thermal movement does not alleviate maintenance problems.

Integral abutments eliminate the need to provide deck joints. In addition, they can save bridge owners a considerable amount of money, time and inconvenience compared to conventional abutments. Because of these reasons, states began building integral abutments. Colorado was the first state to build integral abutments in 1920. Massachusetts, Kansas, Ohio, Oregon, Pennsylvania and South Dakota followed in the 1930s and 1940s. California, New Mexico and Wyoming built integral abutment bridges in the 1950s.

With the National Interstate Highway System construction boom in the late 1950s and mid-1960s, Minnesota, Tennessee, North Dakota, Iowa, Wisconsin and Washington began moving toward continuous bridges with integral abutments as standard construction practice. A testament of their excellent performance throughout the years is the fact that the current policy of the vast majority of states is to build integral abutment bridges whenever possible. This is confirmed by the results of this survey, which indicates that forty-one states are now using integral abutment bridges.

Problems with integral abutment bridges do exist; the severity and cause of problems differ from state to state. The state responses to the 2009 survey on integral abutment bridges conducted by the University of Maryland are shown in Tables 1, 2 and 3. This paper focuses on responses to the following three issues: status of use of integral abutment bridges, problems associated with integral abutment bridges, and construction and maintenance costs of integral abutment bridges compared to conventional bridges. Forty-seven states responded to the survey; responses were not received from Montana, Rhode Island and South Carolina.

Fig. 1. Evolution of integral abutment bridges in the United States.

Use and Problems Associated with Integral Abutment Bridges

The 2009 survey on integral abutment bridges conducted by the University of Maryland indicates that forty-one states are now using integral abutment bridges. Colorado pioneered the use of integral abutment bridges in 1920 followed by Massachusetts in 1930, and Kansas and Ohio in 1935. Eight states — Missouri, Tennessee, California, Iowa, Illinois, Kansas, Washington and Wyoming — have more than 1,000 integral abutment bridges in their inventories. Missouri has more than 4,000 integral abutment bridges and Tennessee has more than 2,000. The state of Washington, having built more than 1,000 integral abutment bridges by the year 2000, has decided to switch to semi-integral abutments.

In addition to being the first state to build integral abutment bridges, Colorado has the longest steel-girder integral abutment bridge in the United States with a length of 1,044 feet and the longest cast-in-place concrete integral abutment bridge with a length of 952 feet. The longest precast concrete integral abutment bridge in the United States was built in Tennessee; it has a length 175 feet.

Table 1 shows responses regarding status of use of integral abutment bridges and problems associated with integral abutment bridges.

Costs Associated with Integral Abutment Bridges

The 2009 survey on integral abutment bridges also addresses the issue of costs associated with the use of integral abutment bridges. Tables 2 and 3 show the state responses on the issue of construction and maintenance costs of integral abutment bridges compared to conventional bridges.

Summary of Responses

The responses to the survey indicate that nine states do not use integral abutment bridges. Out of the nine states that do not use integral abutment bridges, three states (Alabama, Delaware and Louisiana) never used integral abutments, three states (Alaska, Arizona and Mississippi) discontinued their use due to serious problems, and three states (Florida, Texas and Washington) discontinued their use either because they realized no performance advantage over their conventional practice (Florida and Texas) or they concluded that semi-integral abutments offer more advantages compared to integral abutments (Washington). The status of use of integral abutment bridges is illustrated in Figure 2.

The responses also indicate that 25 states have no problems with the use of integral abutment bridges. In addition, 12 states (California, Colorado, Maine, Michigan, Missouri, Nebraska, New Mexico, New York, North Carolina, Oklahoma, Utah and West Virginia) report either minor or moderate problems with the use of integral abutment bridges. Four states (Indiana, Kansas, South Dakota and Virginia) had moderate problems with integral abutment bridges in the past; they found a solution to their problems and do not report any more problems. However, three states (Alaska, Arizona and Mississippi) had serious problems with integral abutment bridges; as a result, each state discontinued their use. The status of problems with integral abutment bridges is illustrated in Figure 3.

The responses to the issue of construction costs of integral abutment bridges compared to conventional bridges indicate a lower construction cost in twenty-seven states, higher construction cost in five states (Arkansas, Georgia, Maryland, Nebraska and Utah), and same construction cost in three states (Indiana, Kansas and New Hampshire). The status of construction costs of integral abutment bridges and conventional bridges is illustrated in Figure 4.

The responses with regard to the issue of maintenance costs of integral abutment bridges compared to conventional bridge indicate a lower maintenance cost in thirty-two states, and same maintenance cost in three states (Georgia, Hawaii and Nebraska). Not surprisingly, no state reports a higher maintenance cost with the use of integral abutment bridges. The status of maintenance costs of integral abutment bridges and conventional bridges is illustrated in Figure 5.

Forty-one states use integral abutment bridges. The number of integral abutment bridges, both statewide and nationwide, has increased considerably in the last few decades. Eight states have more than 1,000 integral abutment bridges; among them, Missouri with more than 4,000 and Tennessee with more than 2,000 integral abutment bridges. The responses received from the state departments of transportation confirm the fact that use of integral abutment bridges almost always results in lower bridge maintenance costs compared to conventional bridges. The responses also confirm that in the vast majority of states, the construction cost of building integral abutment bridges is lower compared to conventional bridges.

In addition, most states report no problems with integral

Figure 5 Status of comparative maintenance costs of integral abutment and conventional bridges

abutment bridges; a limited number of states report minor to moderate problems with the use of integral abutment bridges. A number of states that previously had problems with integral abutment bridges were able to come up with solutions to these problems. As a result, they do not report any more problems with the use of integral abutment bridges.

However, it is very important to recognize that many problems are avoided because integral abutment bridges are built within the limitations imposed by the design parameters outlined in each state’s Bridge Design Manual. These design limitations prohibit the use of integral abutments for very long bridges and in situations that involve complex structural and soil conditions. In addition, there are limitations on skew, curvature and type of piles to name a few.

Apparently, more research on integral abutments is needed in order to advance the use of integral abutment bridges. More research that predicts the behavior of integral bridges based on theory, in addition to empirical evidence will lead to the introduction of national guidelines for integral abutment bridges, which will provide legitimacy to this cost-effective method of bridge construction. The current absence of such a document acts as a deterrent to the use and further advancement of integral abutment bridge construction.

Acknowledgments from the Author

This article is based upon the responses received from the following state departments of transportation: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming. Their help is gratefully acknowledged.

Amde M. Amde (formerly Amde M. Wolde-Tinsae) is a professor of structural engineering in the Department of Civil and Environmental Engineering at University of Maryland. He is also a registered professional engineer and president of AMA & Associates. Other faculty positions held include Iowa State University and McMaster University. He holds two U.S. patents and has published more that 200 technical papers.

Andreas Paraschos is a professional engineer in the state of New York and a structural bridge engineer with the New York City Department of Transportation/ Division of Bridges.

Andreas Parachos

References

1.    Amde, A.M., Chini, S.A. and Mafi, M., “Experimental Study of Piles in Integral Abutment Bridges,” International Journal of Geotechnical and Geological Engineering, 1997, Vol. 15, 343-355.

2.    Amde, A.M. (Wolde-Tinsae, A.M.) and Klinger, J., The State-of-the-Art in Integral Abutment Bridge Design and Construction, AW087-313-046, FHWA/MD-87/07, January 1987, 70 pages.

3.    Amde, A.M. (Wolde-Tinsae, A.M.), Klinger, J. and White, E.J., “Performance of Jointless Bridges,” Journal of the Performance of Constructed Facilities, ASCE, Vol. 2, No. 2, May 1988, pp. 111-125

4.    Amde, A.M. (Wolde-Tinsae, A.M.) and Greimann, L., “General Design Details for Integral Abutment Bridges,” Journal of Civil Engineering Practice, BSCE/ASCE,ISSN: 0886-9685, Vol. 3, No. 2, Fall 1988, pp. 7-20.

5.    Amde, A.M. (Wolde-Tinsae, A.M.), Greimann, L., and Johnson, B., “Performance of Bridge Abutments,” The Journal of the International Association for Bridge and Structural Engineering, IABSE PERIODICA 1/1983, pp. 17-34.

6.    Amde, A.M. (Wolde-Tinsae, A.M.), Greimann, L.F., and Yang, P.S., “End Bearing Piles in Jointless Bridges,” Journal of Structural Engineering, ASCE, Vol. 114, No. 8, August 1988, pp. 1870-1884.

7.    Burke, M.P.,”Integral Bridges.” Transportation Research Record, No. 1275, 1990, pp. 53-61.

8.    Greimann, L. and Amde, A.M. (Wolde-Tinsae, A.M.), “Design Model for Piles in Jointless Bridges,” Journal of Structural Engineering, ASCE, Vol. 114, No. 6, June 1988, pp. 1354-1371.

9.    Greimann, L.F., Amde, A.M. (Wolde-Tinsae, A.M.) and Yang, P.S., “Skewed Bridges with Integral Abutments,” Bridges and Culverts, Transportation Research Record 903, Transportation Research Board, National Academy of Sciences, Washington, D.C., 1983, pp.64-72.

10. Kunin, J., and Alampalli, S, “Integral Abutment Bridges: Current Practice in the United States and Canada,” Special Report 132, Transportation Research and Development Bureau, New York State Department of Transportation, Albany, N.Y., 1999.

11. Maruri, R., and Petro, S, “Integral Abutments and Jointless Bridges 2004 Survey Summary.” Federal Highway Administration and Constructed Facilities Center at West Virginia University, Morgantown, W.V.

Our exclusive survey of bridge conditions in the United States

By Tina Grady Barbaccia

It’s a case of good news/bad news.

Better Roads’ 2010 Annual Bridge Inventory reveals that fewer of the country’s bridges are considered structurally deficient (SD) or functionally obsolete (FO) than any time in the last five years. That’s the good news. The bad news is that the number of bridges in those classifications is still worryingly high.

The nation has 600,513 total bridges, but 23.3 percent — or 139,620 of them — are considered structurally deficient (SD) or functionally obsolete (FO). Of America’s 291,034 total interstate and state bridges, 61,149 – or 21 percent – are SD/FO. There are 309,479 total city/county/township bridges in the United States, and 78,471 — or 25.4 percent — are SD/FO.

But there are 2,278 fewer bridges than last year rated as SD or FO. Last year, out of the 597,787 total bridges surveyed, 141,898 of them — or 23.7 percent — were SD/FO. Compared to last year, there are also fewer SD/FO interstate and state bridges. In 2009, 62,504 — or 21.6 percent of the total 288,920 interstate and state bridges — were SD/FO and 79,394 — 25.7 percent — of the 308,867 city/county/township bridges were found to be SD/FO last year. [Editor’s Note: The 2009 numbers use 2008 data from Massachusetts and 2007 data from Rhode Island because updated numbers were not supplied for the 2009 Bridge Inventory.]

These are some of the findings from the Better Bridges 2010 Annual Bridge Inventory, an original research project conducted annually by Better Roads.

Where the most troubled bridges are

Although our nation’s capital has only 199 bridges, Washington, D.C., has the worst percentage of SD/FO bridges in the nation by overall percentage. Of the District’s 199 bridges, 123 — or 62 percent — are SD or FO, 7 percent more than in 2009.

The District of Columbia’s DOT (DDOT), however, says it expects to lower the rate of deficient bridges in the coming year through rehabilitation and reconstruction projects. But availability of funding remains the greatest challenge in reaching this goal, says Don Cooney, infrastructure project management administrator for the DDOT, in his survey response to Better Roads.

Rhode Island is the second worse, with 417 — 53 percent — of 789 total bridges being SD or FO. The state has 54 percent — 341 — of its 634 total interstate and state bridges in FO or SD condition — and 49 percent — 76 of 155 — of total city/county/township bridges in SD or FO condition. “We have instituted a plan that targets structurally deficient bridges,” David Fish with the Rhode Island DOT points out in his survey response.

The third ranking for combined overall FO/SD bridges is shared by Hawaii and Pennsylvania with a 38-percent rate of overall combined SD/FO bridges. Pennsylvania has a higher rate of problem city/county/township bridges — 46 percent, or 3,143 of its total 6,815 municipal bridges — than Hawaii which also has 36 percent, with 147 of its 403 bridges in SD/FO condition. However, Hawaii has more SD and FO interstate bridges, 39 percent, than Pennsylvania, which has 34 percent or 5,708 of its 16,718 total state and interstate bridges in either SD or FO condition.

But Pennsylvania DOT (PennDOT) has an Accelerated Bridge Program (ABP) that is focused on reduction of structurally deficient bridges, explains James M. Long, P.E., assistant chief bridge engineer. What’s more, “PennDOT has already implemented a design approach for 100-year bridge life to ensure durability,” Long says.

It appears the ABP has made a difference. Last year, Pennsylvania had the most combined structurally deficient and functionally obsolete bridges by state. Of its 23,562 surveyed last year, it had a combined 9,130 — or 39 percent — that were SD/FO. That figure is down 1 percent this year. Although its percentage of SD/FO city/county/township bridges hasn’t changed (46 percent), the state’s percentage of SD/FO state and interstate bridges has decreased by 2 percent from last year’s 36 percent.

The Hawaii DOT also expects to be able to lower its rate of deficient bridges in the coming year, but it will come “very slowly,” says Paul Santo, bridge design engineer for the Hawaii Department of Transportation. “We have prioritized work on these bridges through our bridge management program,” he says.

New York State records the fifth-highest percentage of combined SD/FO bridges with 37 percent of its total 17,405 bridges bearing an SD or FO rating. Breaking it down, 39 percent — 3,215 — of New York’s 8,335 total interstate bridges are SD/FO, and 36 percent — 3,230 — of the state’s 9,070 city/county/township bridges are SD/FO.

Next is a tie between Connecticut and West Virginia with 36 percent of their total bridges in SD/FO condition. West Virginia has more total bridges — 2,509 — in SD/FO condition than Connecticut, which has 1,508 rated as SD/FO. But 71 percent, or 78, of West Virginia’s 110 total city/county/township bridge are SD/FO, while only 34 percent — 424 — of Connecticut’s 1,240 total city/county/township bridges are SD/FO.

The states are close in SD/FO state and interstate bridges. Connecticut has 2,934 total interstate bridges with 1,084 or 37 percent SD/FO. West Virginia is 2 percentage points lower at 35 percent, with 2,431 of its 6,896 total state and interstate bridges classified as SD/FO.

Environmental issues

Agencies report that environmental restrictions and regulations continue to pose problems for replacing and repairing structurally deficient or functionally obsolete bridges. This has been a chronic issue in Better Roads annual surveys.

The District of Columbia DOT says such restrictions do affect how well the agency is able to replace or repair bridges, but concedes that “environmental restrictions are [just] a part of working in an urban environment.”

The Nevada DOT says that environmental restrictions do have an impact on its ability to replace or repair bridges by resulting in a longer lead time for design, “but [they] are not insurmountable.”

For the North Carolina DOT, environmental restrictions mean that “funds are diverted from projects to pay for permits [that are] required.”

The Maine DOT also notes that environmental restrictions bring on “increased costs [that] reduce the number of bridges that can be fixed.”

Kentucky is feeling similar financial pains because of environmental regulations. “Sometimes we are required to stay out of the water due to endangered species,” David Steele, branch manager for the Kentucky Transportation Cabinet, notes in his survey response. “This increases the cost of the job. We then have less money for other bridge jobs.”

In Pennsylvania, permit and regulatory agency requirements are a consideration for project delivery, but don’t necessarily hinder how well the state can replace or repair its deficient bridges, says Long, PennDOT’s assistant chief bridge engineer. “PennDOT funds certain positions within the regulatory agencies as provided under SAFETEA-LU in order to facilitate project delivery,” Long says. “PennDOT also participates in monthly agency coordination meetings, which can also facilitate project delivery.”

Although environmental restrictions do not affect how well Tennessee is able to replace or repair its deficient bridges, they do affect how “quickly and costly (sic) bridges get let to contract for replacement and/or repair,” says Wayne J. Seger, civil engineering manager 2 with the Tennessee DOT’s Bridge Inspection and Repair Office. Michael B. Johnson, the office chief for the California DOT (Caltrans), agrees. He says that “permits slow the replacements and increase development costs.”

Greg Roby, deputy director of structures for the Maryland State Highway Administration, notes in his survey response that the agency is “spending increasing amounts of precious bridge funding to meet environmental (and other) requirements that have little or nothing to do with bridge preservation.”

But not all agencies are being troubled by environmental factors. In fact, the Florida DOT says restrictions haven’t had any impact on how well it is able to replace or repair a bridge.

The biggest problem across the country is lack of funds

Nearly all the state DOTs surveyed cited funding availability the greatest challenge in lowering their rate of deficient bridges. Heavy traffic, routing traffic during work on the structure and scour also came in at the top end of the list.

With the lack of a SAFETEA-LU reauthorization leaving the transportation construction industry in limbo for funding, many state agencies are apprehensive when it comes to planning for major projects. American Reinvestment and Recovery Act (ARRA)’s “stimulus” funds have provided “a good momentum for addressing deficient bridge needs,” says Anwar Ahmad, assistant bridge engineer with the Virginia DOT (VDOT). “These funds were used to refund or rehabilitate 119 deficient structures,” he says, adding that about 20 percent of the bridge work was from ARRA funds.

What’s more, Ahmad notes, VDOT “fortunately has dedicated significant resources to [its] bridge program in the last few years” so insufficient funding shouldn’t restrict important work in the coming year. “The current funding level should be adequate for the delivery of the program this coming year.”

In Texas, which has the most bridges in the nation, 9,148 — or 18 percent — are structurally deficient or functionally obsolete. The Texas State DOT (TxDOT) says it should be able to lower this rate in the coming year. “Replacement priority is to replace ‘50’ [year-old] bridges first,” explains Alan Kowalik, TxDOT’s bridge inspection engineer. The state also has an “equivalent match” program to assist cities and counties with replacing bridges, he says. The Stimulus has also kicked in about 18 percent of funding throughout the past two years to help with the state’s bridge repair and replacement plans.

The Nebraska Department of Roads has also benefitted from ARRA, but the state has also established a dedicated fund to address high-priority bridges, which Steve Anderson, with the agency’s Bridge Division, says should help lower the state’s rate of deficient bridges. However, not surprisingly, Anderson says, “[we] always have more needs than funds.”

In 2009, ARRA funded about 32 percent of Pennsylvania’s bridge work. This year, the stimulus only funded about 4 percent, according to PennDOT. In Nevada, the Stimulus has supplemented zero percent of the state’s work this year, according to David Severns, assistant chief structures engineer with the Nevada Department Transportation (NDOT). But this hasn’t affected the state’s ability to fund important work. Severns says “continued use of federal Highway Bridge Program (HBP) funds” will allow the state to lower its rate of deficient bridges. In fact, the state has been working on one of the biggest bridge projects in the nation — the Hoover Dam Bypass project.

Tennessee, with 19,601 bridges — 3,414 of them, or 17 percent rated as SD/FO — was able to build or replace 81 bridges (48 local, 33 state bridges) with ARRA funds. The Tennessee Department of Transportation (TennDOT) says that insufficient funding is still the biggest challenge in lowering the state’s rate of deficient bridges.

Seger, with TennDOT’s Bridge Inspection and Repair Office, says his agency doesn’t anticipate insufficient funds restricting important work in the coming year. In fact, TennDOT is currently in year two of a three-year program to retire about 200 structurally deficient bridges. But he does point out that when states get federal money for bridges, they should “use it for bridges. Do not allow bridge funds to be diverted to other things.”

Terry Udland, a bridge engineer with the North Dakota Department of Transportation, says that the percentage of work that came from the stimulus this past year was “minimal.” North Dakota has a combined rate of 21 percent of bridges that are SD/FO (out of 4,274 total bridges, 891 are SD/FO), but Udland notes that the state expects to lower its rate of deficient bridges in the coming year by replacing or overlaying deficient decks and through overall bridge replacements.

Maryland bridge authorities report that the state received a “modest amount” of ARRA funding for bridges, which it in turn applied to replacing, repairing or painting about 35 bridges.

The Stimulus also modestly helped the Oklahoma DOT (ODOT), which says that Stimulus money accounted for about 16 percent of its work. “It has had a very positive impact on bridge work in the state,” said Oklahoma’s survey respondent. The funds have allowed the re-decking of more than 40 bridges on I-244 in Tulsa, more commonly known as part of the Inner Dispersal Loop. “Due to many years of neglect, ODOT has fallen behind in the bridge programs,” according to the state agency. “In recent years, Oklahoma has made tremendous progress in continued and consistent funding, which is critical to improve bridge conditions.” An example of this progress is ODOT’s eight-year construction work plan that has allocated $361.3 million for bridge work in federal fiscal year 2011.

For the Georgia DOT, the stimulus didn’t supplement the agency at all because “[we] did not have plans on the shelf,” says Mike Clements, state bridge maintenance engineer with the Georgia DOT.

Eric J. Christie, assistant state maintenance engineer for bridges at the Alabama DOT, answered “no” when asked whether the state expects to be able to lower its rate of deficient bridges in the coming year.

Where now?

Better Roads asked that with all the funding uncertainty, what major overhauls can be made to the system of planning, building and maintaining bridges in the nation at the federal state and local level?

The answer is continued and consistent funding, with the flexibility to address the most critical needs, says the Oklahoma DOT. Paul Santo, bridge design engineer with the Hawaii DOT, says there needs to be “more funding at all levels.”

Jeff C. Vigil, state bridge management engineer for the New Mexico DOT, says that “funding needs to be given to local bridges and lower-priority highway bridges on the state and federal system.” In addition to funding, though, Vigil notes, “more preventative bridge maintenance funding would greatly keep bridge future funding needs down.”

Louisiana DOT’s Bridge Engineer Manager Ray Mumphrey also agrees that more money needs to be spent on maintenance. TxDOT’s Kowalik says a dedicated bridge maintenance fund should be developed.

Other major overhauls suggested are the expansion of eligible work under the Highway Bridge Program (HBP) and considering the bridge development timetable so it’s reflected in future legislation. In overhauling the nation’s bridge program at the federal, state and local level, “uniformity in rules and a more streamlined process for the bridge program” should also be considered, says Cody Axlund, bridge inventory/inspection engineer for the South Dakota DOT.

Where and how could the nation even begin to implement these ideas and overhaul the planning, building and maintenance system for bridges, asked the survey?

Ahmad, with the Virginia Department of Transportation (VDOT), recommends developing a strategic approach at the federal, state and local levels “to deliver the most reliable bridge inventory in the world.”

The strategic approach can be accomplished, Anwar says, by dedicating adequate and sustained funding and resources to three distinct programs. He suggests a preventive/preservation program, a rehabilitation program, and a replacement program.

“The three programs should be based on life cycle and assets management principles,” Anwar advises. “Develop policies and processes around these programs that ensure consistency in measuring the effectiveness of these programs.”

Q and A

If you could change any aspect of your department to improve your bridges, what would it be?

Anwar Ahmad, assistant bridge engineer with the Virginia Department of Transportation (VDOT): “Direct more resources towards bridge preservation to perform cyclical preservation activities [on bridges] that are in fair to good conditions; improve design practices to construct maintenance-friendly bridges, i.e. eliminate expansion joints when possible; use corrosion-resistant steel reinforcement; place flexible wearing surface on newly constructed bridges with impenetrable membrane; and schedule the replacement of the overlay on a standard cycle, i.e. five, 10, or 15 years. Currently, VDOT is in the process of implementing most of these recommendations. ”

Wayne J. Seger, civil engineering manager 2 with Tennessee Department of Transportation’s bridge inspection and repair office: “Do more annual bridge cleaning, especially of expansion joints and steel trusses. Remove animal deposits, i.e. nests, etc.”

Lee Floyd, bridge maintenance engineer with the South Carolina Department of Highways: “[I’d change the] project selection process. [It’s] too simplified and not responsive to highest needs.”

Ray Mumphrey, bridge engineer manager with the Louisiana Department of Transportation: “Build more bridges with department personnel.”

David Severns, assistant chief structures engineer with the Nevada Department of Transportation: “Implement a bridge management system and more systematic bridge maintenance.”

Dan Holderman, bridge management engineer with the North Carolina Department of Transportation: “Commit more funding to bridge rehabilitation and replacement.”

Alan Kowalik, bridge inspection engineer with the Texas State Department of Transportation: “More bridge maintenance [to] maintain bridges to keep from becoming ‘50.’”

Charles P. Brand, bridge engineer for the Arkansas State Highway Transportation Department: “Implement bridge management for systematic maintenance of bridges to more effectively maintain our bridges with the money available.”

For the FHWA’s explanation of what makes a bridge structurally deficient and how a bridge becomes functionally obsolete, go to http://www.fhwa.dot.gov/policy/2008cpr/chap3.htm#7.

Better Roads’ editorial staff would like to thank all the state highway engineers for their continuing cooperation and special effort to provide current data. The data was collected through October 2010.  Click Here for pdf of 2010 Report.

How deficient and obsolete bridges break out in 2010

States and the District of Columbia have provided separate counts for the latest numbers on the breakdown of their structurally deficient (SD) and functionally obsolete (FO) bridges.

Q & A

If you could change any aspect of your department to improve your bridges, what would it be?

Jean A. Nehme, state bridge engineer for the Arizona Department of Transportation: “Additional funding. Additional funding will allow [our agency] to repair/replace more bridges.”

Mark Leonard, staff bridge engineer with the Colorado Department of Transportation: “It would be helpful to have more consistent and predictable long-term federal and state funding streams.”

Travis McDaniel, bridge engineer with the Wisconsin Department of Transportation: “More preventive maintenance [so there is] less long-term deterioration.”

Ruby Bradley, Geometric & Accident Unit with the Kansas Department of Transportation: “Reduce environmental constraints [because it causes] delays and extra work.”

Jeff C. Vigil, state bridge management engineer with the New Mexico Department of Transportation: “Increase funding on secondary routes. Improve construction training.”

Oklahoma Department of Transportation (from media department): “Add more bridges and bridge inspectors. Additional qualified personnel would help keep our inspections current and further improve the quality.”

Jim Pierce, bridge management engineer for Minnesota Bridges and Structures: “Keep higher funding levels in place to maintain a sustainable network conditions level.”

Don Cooney, infrastructure project administrator with the Washington, D.C., Department of Transportation Asset Management Division: “Increase funding for preventive maintenance.”

Benjamin W. Foster, assistant bridge maintenance engineer with the Maine Department of Transportation: “Increased costs reduces [the] number of bridges that can be fixed.”

Charles P. Brand, bridge engineer with the Arkansas State Highway Transportation Department: “Implement bridge management for systematic maintenance of bridges to more effectively maintain our bridges with the money available.”

David Steele, branch manager with the Kentucky Transportation Cabinet: “Do more preventive maintenance and concentrate on making bridges more maintenance friendly. In the long run, it would cost less to maintain a bridge and they will last longer.”

This rendering shows how the new Willamette River Bridge will look upon completion.

By Tina Grady Barbaccia

A bridge project that started out under intense scrutiny in an environmentally- sensitive area is now being cheered and even has the locals putting their own touch on the bridge.

The Oregon Department of Transportation (ODOT) credits this to using the construction manager/general contractor (CM/GC) approach — where the contractor works with an agency from the beginning of the project instead of after a design has already been developed.

Looking north at I-5, pictured (from left to right) are the work bridge, the decommissioned bridge and the new, temporary detour structure. The decommissioned structure in the photo has since been demolished.

The Interstate 5 deck arch type bridge over the Willamette River is a $201-million replacement project located at milepost 192.7, where it crosses the river between the cities of Eugene and Springfield. It was funded by the 2003 Oregon Transportation Investment Act and the federal Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) program.

“The biggest advantage [to using a CM/GC approach] is the flexibility to balance the public’s expectations while maintaining the level of public participation the owner wants to provide,” explains Kevin Parrish, project manager with Springfield, Ore.,-based Hamilton Construction, which is the construction manager/general contractor on the bridge project.

Traditionally, an agency would determine a project’s scope, the project design, and the schedule. Then, the amount of money to be spent on a project was determined. “A designer would work up the project, put it out to bid, and the contractor with the lowest price would get the project,” Parrish explains. “Then the public would see it.” With the CM/GC approach, the contractor is involved in the entire process. This approach isn’t new. It’s common in the private sector, but for DOTs, it’s considered to be an innovative approach.

A steel rebar reinforcement cage for bent 6 will be placed into the bent to support and reinforce the structure. The orange signs visible on the bridge in the background are part of the project’s “gawker screen,” a barrier used to prevent drivers from staring at the construction site and keep focused on the road.

“We hire the contractor at the start of the design,” explains Dick Upton, major projects unit manager for ODOT and project manager for the I-5 bridge project. “As construction manager, he [the contractor] and his team work with us through design, fundamentally giving constructability reviews and more or less guiding our construction approach to the way he would prefer to approach the job.”

This is a pilot program for ODOT, and one of the first times this approach has ever been used on horizontal construction. “Before we launched down this path, we did a scan of agencies doing it,” he says. Only Arizona and Utah were currently using the CM/GC approach. “Now Nevada is calling and asking questions [about our approach] too,” Upton says.

Vocal locals

Involving the public from the start was a must.

“In Eugene, members of the community take a high interest in publicly-funded projects,” Parrish says. “The locals are very vocal.”

ODOT is using the high level of interest in the project to help shape the design of the bridge and the surrounding natural area. “There have been some projects that haven’t gone over as well, and ODOT has learned from that,” Parrish says. “ODOT wants to serve the public good. A project that could have generated a lot of negative publicity is now providing eagerly anticipated improvements and enhancements to the surrounding area.”

The bridge project crosses directly over the Whilamut Natural Area, which includes two well-used and very popular bike systems that lead up to the bridge but were not connected. Replacement of the bridge affects usage of the trails.

The CM/GC approach enabled the public to be part of the entire replacement process, and to be sensitive to the needs of the community with how the bridge replacement would affect the bike trail usage. It has helped to make a delicate situation quite manageable, by further keeping the community closely involved in the bridge replacement project. Bridge designers were brought in and the two paths will now be connected, a much-anticipated improvement for the area’s large cycling community. For the community, these improvements have become as important to the locals as the bridge project itself — almost as if it were a bike trail project with a minor bridge component.

“Instead of coming in with plans already in place, ODOT asked us to involve the community,” Parrish notes, adding that it has worked well. “The communities here have a love-hate relationship with construction. This really shows up in our citizen groups. The most unique feature of advancing this project is the citizen group ODOT put together to help guide the bridge design development and contribute and comment on the aesthetics of the structure.”

The bridge is in a prominent place in the community, so the aesthetics are important. In addition to serving as the gateway to Eugene-Springfield, the bridge bisects one of the largest parks in the area. Artistic features on and around the bridge are being imprinted into the concrete by a local design team.

In the beginning

In 2001, ODOT began inspecting bridges for cracks. Bridge inspection reports in 2002 showed shear cracks growing quicker than expected throughout the reinforced concrete beams supporting the original bridge deck. This raised concerns that the bridge would not stand up to traffic unless truck weight restrictions were imposed, or a detour route could be provided. Recognizing the lengthy public process required to design and permit the permanent replacement structure, ODOT designed a detour bridge to carry I-5 traffic until the new structure was in place.

The detour bridge was designed, permitted, and advertised under an “A+B” contract method that considered the construction schedule as well as the contract amount to determine the “best value” for award. Hamilton Construction won the award in September 2003, and opened the bridge to traffic less than a year later.

The original bridge — the decommissioned bridge — couldn’t support the traffic it was carrying and needed to be taken out of service. ODOT immediately realized there was a problem: they either needed to build a replacement bridge or they would have to detour trucks off Interstate 5 and send them right through downtown Eugene on old Highway 99. “ODOT raced to quickly design a replacement bridge,” Parrish says. “It had to come up with the simplest bridge to design and construct to get it done quickly. There was not a lot of time for public input, and the only access for construction to it was through the Alton Baker Park natural area.”

Having the public on its side has made a big difference, Parrish notes, especially when working to obtain a permit. This can often be a long, tedious process, but in an environmentally-sensitive area it’s even more of a slippery slope. To add more traction to this slope, ODOT developed its programmatic permitting process to speed environmental approvals. ODOT met with all the regulatory agencies that are involved in the bridge rebuilding process and proposed that they jointly develop a set of standards that — if complied with — would enable the agency to secure a permit in a timely manner. “With these permits, whoever is submitting for them must have definitive information on how a project will be built,” Parrish says. “The whole idea is to minimize the impact by putting as little material in the river as possible. If the project was designed as a design-bid-build project, you’d either have to pay a contractor to comply with the designer’s assumed construction methods, or delay the project until the permit could be modified to comply with the contractor’s construction methods.”

Hamilton Construction helped ODOT and their designer, OBEC Consulting Engineers, put together a permit application denoting exactly how the bridge was going to be built, including temporary work systems and contracts. “With the decommissioned bridge being a box girder, we have to collect 100 percent of the rubble and debris on our containment,” Parrish says. “Consequently, we developed a demolition plan that utilizes a containment platform that allows us to run equipment, and to collect and support all the concrete rubble during the demolition process. But all of this planning was done very early in the process to find the best balance between our preferred construction methods and the requirements of the regulatory agencies. This should allow us to deal with fewer variances.”

Using a CM/GC approach enables construction of temporary work, such as site preparation, access roads, and demolition work, to start before completion of the final bridge design. “This was done as part of the process to come up with pricing,” Parrish says. “Early work packages enable us to identify portions of a project that we can isolate out as a unique section to determine the scope clearly and definitively. The CM/GC delivery method allows us to start work on these early work packages right away — and to work on them concurrently instead of consecutively.”

In good times and in bad

However, with all good things oftentimes challenges do arise. Despite the advantages, some of the details and other minutiae proved to be challenging.

“We have struggled with the intricacies of the contract,” Parrish says. “Agencies aren’t used to seeing indirect costs.”

With the CM/GC approach, all cost negotiations are done on an open book basis. “That means once we start negotiations or are working through estimates, we show material quotes, subcontractor quotes, our production rates, etcetera,” Parrish continues. “Normally, an agency never sees this. It just sees the bid price, which has costs, markups, contingencies, etcetera. Agencies are seeing an incredible amount of details. If they haven’t worked as a contract, they don’t know how estimates are put together.”

Parrish advises that agencies considering the CM/GC approach be very clear with what they want to see and how projects are broken down. “There are general conditions components — onsite trailers, risks, etcetera,” Parrish says.

He adds that the real message that should go out is that it’s important for agencies to understand components of a contractor’s price – i.e. what goes into an estimate. “These components are cost of work, labor, material and equipment costs, general conditions cost, risk cost, and profile or overhead for the contractor,” Parrish points out. “The contractor’s profits are what pay the taxes to support the agency. The CM/GC is where our profit is to reside.” v

Oil Change

Kevin Parrish, project manager with Hamilton Construction, the construction manager/general contractor on the Interstate 5

Willamette River bridge project, explains that all of the company’s ‘diesel’ pile hammers run on biodegradeable oils instead of diesel, not just the WRB hammers. “The best vegetable oil we have found is soybean oil, second best is peanut oil, with canola oil the third best choice,” Parrish explains. “Soybean oil is low in trans fats, which prevents the pile hammer arteries from clogging, just like your heart. The other vegetable oils can start to solidify in the fuel tank if the tank is not drained after each use. The little solid particles can then clog the injectors, which prevents the hammer from firing.”

Fast Facts:

The Willamette River Bridge Replacement Project

The new northbound Interstate 5 Willamette River Bridge in Eugene will measure approximately 1,985 feet.

The demolition containment structure is approximately 127,500 square feet.

For every tree that is cleared because of construction, the Oregon Department of Transportation will replace it with at least two native trees at the completion of the project in 2013. The native species that will be planted include Western red cedars, Oregon ashes, Brayshaw black cottonwoods, Oregon white oaks, big leaf maples and red alders.

At Better Roads press time, Hamilton Construction had used approximately 14 million pounds of steel beams and piling in the work bridge and demo containment structures, along with nearly 2 million board feet of timber decking.

The Oregon Department of Transportation (ODOT) anticipates that 400,000 hours of construction trade work will be required to replace the I-5 Willamette River Bridge.  

The construction team plans to recycle 50,000 tons of concrete.

On the Social Side

Willamette River Bridge blog (ODOT’s first blog in agency history):

http://willametteriverbridge.blogspot.com/

Willamette River Bridge construction update:

http://www.youtube.com/user/OregonDOT#p/u/O/388KpCzlex4

Willamette River Bridge PSA:

http://www.youtube.com/user/OregonDOT#p/u/1/6U1gQwefcks

The Route 219 deck arch bridge over Cattaraugus Creek in New York used a complex tie system, a massive crane and a creative erection process.

By Tina Grady Barbaccia

The arch erection process for this bridge used a complex tie system that used adjustability as its key. Three ties were used: An anchorage tie, which connects the top of the permanent concrete pier bent to the anchorage, and two other ties.

For the construction sequence of a deck arch bridge in New York, these were also the keys to the erection of two 460-foot-long twin arches — part of a 750-foot-long bridge over the Cattaraugus Creek. The twin arches are part of a larger $100 million, 4.2-mile highway expansion and improvement project of new construction on Route 219 south of Buffalo, N.Y. The entire Route 219 was designed in 12 sections, four of which are complete, from West Seneca to Springville. The current section under construction begins at Route 39 in Springville and extends to Peters Road in Ashford.

The overall project is intended to address safety and operational deficiencies and the increased truck traffic along the corridor and to enhance regional and statewide economicdevelopment. The roadway consisted of two lanes in each direction and 11 bridges, including the one over the Cattaraugus Creek.

Using a unique approach to arch bridge construction, engineers designed an erection sequence where permanent bridge columns on each side of the Cattaraugus Creek supported the arches during erection. The arches were held in place by ties attached at two points on each arch. The key to the success of this erection process was the adjustability of the ties.

“No doubt, the adjustability was key,” notes Stephen J. Percassi, P.E., project engineer for Erdman Anthony, the company who assisted Woodbury, N.J.-based general contractor Cornell & Company’s in-house engineer with the unique bridge erection process. “Without it, this procedure wouldn’t be possible. We had to have enough adjustability to effectively transfer all the weight from tie No. 2 to the arches so they could act like arches. Three ties were used: An anchorage tie, which connects the top of the permanent concrete pier bent to the anchorage, and two other ties.

“The other two ties — tie No. 1 and tie No. 2 — bear all of the weight,” Percassi says. “We essentially hang all the weight of the arch on them.” The arch was broken into five pieces per half. Each piece was added sequentially, which in turn pulled on tie No. 1 and No. 2, which then pulled on the concrete anchorage/reaction block. “We designed this system so it only needs one arch tie at any given time,” Percassi explains. “It never uses both simultaneously. We designed it this way for adjustability.”

Tie No. 1 was fixed in length and had a hinge at about the one-third point in its length. Tie No. 2 was “the workhorse of the whole system,” Percassi says. Tie No. 2 was designed to have 12 inches of adjustment. When the erector — the Erdman Anthony/Cornell & Company team — installed it, everything was hooked on the tie, he says. “The adjustability of tie No. 2 allowed us to purposely shorten it, erect the arch higher and lower it later,” Percassi says.

This is extremely significant, Percassi points out, because when tie No. 2 was intentionally shortened, it rotated the arch backward. This was possible because tie No. 1 had a hinge on it.

“Tie No. 1 can’t take the compression because it has a hinge on it,” Percassi says. “The hinge in tie No. 1 allows 100 percent of the force to be transferred to tie No. 2.” At this point, tie No. 1 is not doing anything. After the installation of tie No. 2, tie No. 1 isn’t needed anymore.”

After all of five segments that the arch was broken into have been installed, the largest load has been produced. “Once the fifth piece was added, it produced the largest load — 515,000 pounds — on tie No. 2.”

Not according to the ‘original’ plan

This unique process wasn’t part of the original plan. The New York State Department of Transportation (NYSDOT), owner of the bridge and engineer of for its design, initially recommended that a temporary tower be erected to support the arches during construction. The contractor, Akron, N.Y.-based Cold Spring Construction, subcontracted with Cornell & Company to erect the twin 750-foot arch structures. Cornell then hired Erdman Anthony to act as the erection engineer and to assist with putting together the erection procedures and help secure approval from NYSDOT.

“As part of the design process, we suggested an erection procedure,” says Art Yannotti, director of the Structures Design Bureau for NYSDOT. “For the most part, we don’t usually put together a construction sequence on the design plans. It’s up to the contractor to decide how to erect it and submit to the department [NYSDOT] for approval.”

However, because of the complexity of the bridge construction, Yannotti says, NYSDOT put together a possible construction sequence. The contractor submitted its plan and then hired Erdman Anthony. “The contractor had found a better way of doing it,” Yannotti says. With the help of Erdman Anthony, an alternative design was used to save both time and money.

In short, the modified design increased the six nearly equal-length arch segments to 10 segments, with two initial large segments that were supported by the arch ties and three much smaller segments. Essentially, until connecting the arch at the crown, much of the arch hung like a cantilever over the creek.

Once both sides of the arch were erected, the 18-inch gap at the crown was closed by carefully releasing tension on the arch ties. The land end of the arches was attached to a hinged arch bearing, which allowed them to slowly rotate into place as the tension on the arch ties was loosened.

“This was where the importance of the adjustability of tie No. 2 came into play,” Percassi says. “It’s like standing on top of a diving board. It deflected downward—cantilevered—dangling over the gorge.” The downward deflection is typical of cantilevers, but it’s also what complicated the overall system even more because it required an additional temporary pin at the crown of the arches to allow the two halves to be leaned into one another.

When the top of the arches touched, a temporary 4-inch flange pin was inserted at the top flange. Then a permanent crown pin was inserted in the middle and the temporary pin was eventually removed. “The middle pin is the one that remains for the duration of the structure.”

An enormous crane

In addition to adjustability, one of the other most essential parts of the modified design was the use of a unique crane configuration by Cornell & Company. The project used a Manitowoc 888 ringer crane with 275-foot boom and a 140-foot, 10-degree offset jib. This enormous crane configuration is only one of about five in North America, according to information currently available to Erdman Anthony and NYSDOT.

The crane had 1.4 million pounds of counterweight hanging off the back of it. The outside diameter of the crane’s ring was 51 feet, 2 inches. Use of this size crane and the placement is different than the original suggested NYSDOT construction sequence in that only one enormous crane was used instead of several cranes placed on the structure itself.

“This was needed because of the location at Cattaraugus Creek,” explains Percassi. “We found it easier to keep the crane on the edges of the gorge and erect the arch from halfway across the top.”

Once the crane was in place, a crane pad (developed by contractor Cold Spring Construction) had to be engineered. The crane was used to set the pieces from behind the abutment so special a crane pad had to be built. This process took a significant level of design because it is immediately behind the abutment, Percassi points out.

The erection of the Route 219 Bridge over Cattaraugus Creek project used a unique crane configuration. A ringer crane with 275-foot boom and a 140-foot, 10-degree offset jib with 1.4 million pounds of counterweight was used.

“When you load the crane with the heavy pieces [the crane] is picking up, it will in turn load the abutment,” Percassi notes. “We needed to ensure the crane and the abutment were to remain stable.”

Solid rods were drilled into the earth and into the bedrock and anchors were put in place. Drilled tiebacks, installed by subcontractor Herbert F. Darling, were used to develop a concrete anchorage that was able to resist the pullout force from the erection procedure. Additional piles also were drilled to support the concrete anchorage, also referred to as reaction block.

“The effects of the erection procedure will try to pull the tiebacks out,” Percassi explains, so Cold Spring Construction conducted load testing. “The tiebacks were proof tested to 133 percent of the design load and locked off at 5 percent of it. An additional 40,556 pounds of a mechanically stabilized earth system, or MSES, was required for crane support. The crane was set up on 34 support pedestals — each pedestal was 20.83 square feet — with 14 layers of MSES geogrid reinforcement behind the bridge abutment atop the gorge.

“The most important thing is that the crane pad is engineered to resist the loads induced by the crane,” Percassi points out. The crane pad was engineered to accept 13,720 psf of applied stress.

Careful calculations

Once the crane pad was set up and the crane put in place, the erection of the steel started. With plans to use as few temporary pieces as possible, the permanent structure was used in the arch erection. Percassi says that only about 12 temporary pieces were used per arch.

The temporary pieces — or ties — were installed. Three ties were used. One of the ties was the anchorage tie that connected the top of the bent to the concrete anchorage/reaction block. The other two ties — tie No. 1 and No. 2 — essentially carried the weight of the arch to restrain it from falling into the gorge. The anchorage tie resisted the loads from these two ties.

“Instead of cabling the tiebacks, they used tiebacks out of structural steel and then were able to make threaded rod adjustments in tiebacks instead of adjusting the cable to try to close the arch,” Yannotti says. “It’s a lot easier to make adjustments in the vertical method than in the traditional method. They correct the initial position because of the amount of adjustment in the cable was limited. This allowed them the flexibility of adjusting the arch itself so it was easier to make adjustments in erection procedure itself.”

Percassi adds that careful calculation went into confirming the amount of adjustability required. “We would have otherwise had to find another method to transfer the rest of the load to the arches,” Percassi says. “This would have added more time and cost. It’s very important to make sure you account for as many unknowns as possible.”

The bridge itself has been completed, but it is not yet open to traffic. Currently, the ETA for opening the bridge is at the end of this construction season.

Erection of the bridge began in April 2008. Prior to this, quite a bit of substructure had to occur before the erection process could take place. The arches were completed in Fall 2009 with a concrete deck. The erection was finished in Spring 2009, and the deck was placed in the Summer/Fall of 2009. v

For more stories and photos of this exceptional bridge go to our digital edition at www.BetterRoads.com.

For more information from the NYSDOT about this project, go to http://www.bit.ly/Rte219project.

New technology bringing new standards to measuring bridge conditions

By Tom Kuennen, Contributing Editor

“Smart” bridges are on the way for road agencies burdened with the responsibility of monitoring bridge conditions.

Not-so-old technologies like ground penetrating radar (GPR), acoustic emissions testing and lasers for bridge condition testing are being augmented with advanced mobile radar and laser technologies and today’s nanotechnology, which puts the science of bridge condition monitoring into a whole new era with products such as bridge coatings which can sense trouble within.

In the meantime, reliable, low-cost cellular phone service has lowered the barrier to remote reporting of bridge conditions, as battery-powered systems can “call in” condition reports to an agency computer and database or alert an agency if conditions change abruptly.

Today’s benefits can include better information about bridge conditions, a better database for National Bridge Inventory (NBI) reporting, and, long term, fewer demands on personnel for inspection. But field implementation depends on the ability to make high technology marketable in the field, and on the ability of cash-strapped agencies to pay for it.

Rewards, Barriers to Implementation

Nanotechnology is the latest permutation of bridge condition monitoring, but it caps a decade-and-a-half of activity in high-tech bridge condition monitoring.

“Advanced bridge condition monitoring techniques can provide quantitative condition measurements, as opposed to the subjective assessments that a visual inspector provides,” said Dr. Steven B. Chase, research professor of civil engineering, University of Virginia-Charlotteville Center for Transportation Studies, where he works following a 30-year career with the Federal Highway Administration.

“Many of the new methods can provide indications of conditions that exist prior to a visual indication,” Chase said. “And many of the technologies can measure things that simply aren’t visual.”

Current federal regulations require that a state conduct a bridge inspection every two years. With a total of about 583,000 bridges in the national inventory, in order to inspect nearly 300,000 bridges nationally with the amount of manpower that’s available, efficient and rapid assessments and inspections are required. Today’s new technologies can provide that.

But there are built-in barriers to implementation. Past data, and systems put in place to record the results of those inspections, have been predicated on use of visual inspection, not high-tech. “It will be a long time before these new technologies supplant or add a great deal of opportunity for an agency to save money,” Chase told Better Roads. “The case will have to be made that technology can provide better inspections, with a higher probability of finding a defect that could be significant.”

And staff will have to be trained, he said. “The use of all this technology does require a higher level of capability, training and experience that the typical bridge inspectors do not have,” Chase said. “We’re trying to change that by making the technology easier to use, and produce results that are easier to interpret. We want to change bridge management and inspection practices to integrate the kind of quantitative information this technology can provide, in a way that produces better decision-making. But we have been involved in this a long time, and it will evolve over time. I don’t expect any easy breakthroughs.”

Nonetheless, Chase and his fellow researchers have been fighting to bring the technology to the field. “We are working to bring this technology to bear, to make it easier to apply and to improve the quality of information that’s available to the bridge owners from inspections,” Chase said.

Focus: Decks and Superstructures

For rating and NBI purposes, states must collect condition data on a variety of bridge structural characteristics, including, according to Chase:

The bridge deck and all wearing surfaces

The bridge superstructure, including all primary load-carrying members and connections

The bridge substructure, including the abutments and all piers

Culverts, for culvert bridges, and

Channel and channel protective systems for all structures which cross waterways.

In addition to structural condition, bridge functional adequacy also is logged. This can include load carrying capacities, whether deck geometry or lane constrictions restrict safety, the presence of low underclearances that may result in detours, and the ability of the bridge to handle water flow rates.

Bridge condition technologies are centered on decks and superstructures, and much less on substructures. “Cracks in steel and concrete, damage from corrosion, all are areas in which various technologies are available for assessment,” Chase said. “There’s a lot of work on bridge decks and superstructures. By themselves, cables have been the focus of a lot of attention.”

But except for scour, the condition technologies available for bridge substructures tend to be focused on evaluating the quality of the substructure as it’s constructed, not after it’s in-place, said Chase.

“Evaluating the integrity of piles, drilled shafts and other substructure elements while they’re being constructed has evolved to the point where technology such as cross hole sonic logging and other methods are routinely employed to assess whether substructure elements are constructed properly,” he said. “But once the bridge is placed in service, we tend not to be too concerned with the substructure, with the one exception of scour. That’s because we tend not to have large failures of substructure elements; most of the collapses or other failures have been things that happen in the superstructure.”

Ground Penetrating Radar

Like with pavements, ground penetrating radar (GPR) has great applicability for studying bridge deck condition. GPR systems use electromagnetic radiation at microwave frequencies, and the radiation penetrates and characterizes concrete, while reflecting off metallic material like rebar. It has the potential to replace manual chain drag testing of decks, in which experienced staff listen to the sound the chain makes; ringing indicates a sound spot, while a dull thud indicates subsurface delamination.

A wireless sensing system from MicroStrain Inc., Williston, Vt., was installed on the I-95 Gold Star Bridge over the Thames River at New London, Conn.

The FHWA pioneered GPR for bridge decks by underwriting the development of the HERMES (High-Speed Electromagnetic Roadway Measurement and Evaluation System) product at the Lawrence Livermore National Laboratories in California. HERMES was intended to provide a GPR system that can reliably detect, quantify and image delaminations in bridge decks, at normal highway speeds, and was delivered in 1998.

“HERMES was a radar system that was much, much smaller than anything at the time was commercially available,” said Chase. “It had a much higher frequency, and was based on new technology that had been developed for producing extremely short, precisely timed pulses, which was created for Livermore’s work on fusion reactors. The integration of all of that into a system that employed computer-aided tomography, with an array of antennas, was a first.”

PERES/HERMES II system on Carter Creek Bridge, Dumfries, Va.

HERMES included a computer workstation and storage device, survey wheel, and control electronics, in addition to the array of 64 antenna modules or transceivers mounted in a towable trailer. To investigate specific areas of a bridge deck that require more detailed study, a single-antenna scanning device called PERES (Precision Electromagnetic Roadway Evaluation System) was developed as an extension of HERMES.

In mid-decade they both were supplanted by HERMES II/PERES, new GPR technology using a single transmitter and receiver antenna pair configuration, developed under a participating states’ pooled fund. Work using HERMES II/PERES incorporating other technologies continued into 2009 under the auspices of the University of Vermont.

A variation of this technology is the digital synthesis arrayed radar. HERMES and most radar systems employ a very short pulse, radiated into the deck as a very broad-band signal. “The pulses are on the order in picoseconds [one trillionths of a second], and the frequency content are in gigahertz [billions of cycles per second],” Chase said. “But they are very low energy, spread out over a broad band. Short wavelengths give you more detail, but don’t propagate very far into a material. Lower frequencies give you less resolution, but go deeper.

“What the digital synthesis radar does is, rather than rely on a pulse, it synthesizes [creates] a particular frequency digitally, and radiates that specific frequency,” Chase said. “By hopping or changing frequencies rapidly you can ‘interrogate’ the bridge deck, and it makes it easier to comply with prohibitions on intentional radiation of electromagnetic energy in certain protected wavelengths.”

Acoustic Emission Technology

Acoustic emission technology is a process especially suited for steel bridges, by which engineers “listen” for characteristic signals associated with cracks forming and extending.

“It’s used primarily for detecting and locating fatigue cracks in steel highway structures, and it’s a technology used in a variety of other industries,” Chase said. “When energy is released as a crack propagates, a series of stress waves are generated that can be detected with sensitive accelerometers, combined with sophisticated signal processing that separates those signals from the rest of the noise of a highway bridge.”

Acoustic emission technology is central to a new technology from the Center for Advanced Materials and Smart Structures at North Carolina A&T State University.

There, in 2007, Dr. Mannur Sundaresan, professor of mechanical engineering, developed a single-channel continuous sensor that has the potential to detect and locate early crack growth in structures, thereby providing timely information to prevent catastrophic failures. This single channel continuous sensor can detect the leading edge of the acoustic emission event, occurring anywhere in the region covered by the sensor.

Essentially, the technology involves using commercially-available sensors deployed in a unique configuration to acoustically monitor structural integrity to remotely detect and address standard flaws via acoustic emission signals.

According to Sundaresan, the technology operates like the body’s nervous system. “If you’re hurt, the nervous system lets you know right away,” he said. “That doesn’t happen with a structure. An inspector has to go look. With small cracks, it’s like finding a needle in a haystack. Small cracks are like cancer. They’re usually not noticed until they’ve grown large enough to cause serious damage. These sensors will detect the growth of cracks in their early stages just as our nervous system alerts us of any injury immediately so that we can take action to limit the damage.”

Smart Structures

Even as development of GPR and acoustic systems progresses, attention is shifting to how structures themselves may be outfitted to provide condition data. These “smart” bridges comprise an exciting new opportunity for advanced bridge monitoring.

Smart systems will have several advantages over GPR-based systems. They can provide information that is continuous and that takes place between survey visits. They can measure elements that GPR cannot measure, such as stress, strain, temperature, displacement and vibration, all of which are very useful in determining what is going on in a bridge structure. And they can measure performance instead of detecting damage, providing quantitative information, such as the scenario behind the generation of fatigue cracks.

“The definition of ‘smart structures’ has changed over time,” Chase said. “The National Nanotechnology Initiative has been important in producing new technology that can be turned into a sensor at a scale much, much smaller than before. And the new wireless communication technologies and miniaturization of computers are helping to bring the application of this sensor technology to civil structures. So it’s now possible to deploy multiple sensors – that are relatively small – that do not require much power and can more easily interrogate the structure at hand.”

For example, small, wireless sensors can be can be attached to bridge superstructures to measure variables such as strain, tilt, vibrations, temperature, and seismic activity. Using this technology, it’s possible to rapidly instrument a bridge at fatigue-prone or critical details, and measure what happens under traffic and wind loading.

Another example: recently a wireless sensing system from MicroStrain Inc., Williston, Vt., was installed on the I-95 Gold Star Bridge over the Thames River at New London, Conn. The sensors are powered via 6-in. by 9-in. photovoltaic panels, linked to rechargeable batteries which power microelectronic modules that record data from inside watertight enclosures. The data are wirelessly transmitted to an agency database. Because they are solar-powered, there is no need to manually replace batteries, a benefit as the sensors may be installed in hard-to-access places.

“Just the expense of running power cables to dozens or hundreds of sensors can be more expensive than the sensors themselves,” Chase said. “If we can get away from the need to have wires, and have inexpensive sensors that are compatible with wireless communication and data acquisition systems, and are tailored to the particular job they are asked to do, then it becomes economically possible to implement a system that will actually measure what’s going in multiple locations in a bridge in response to age, deterioration or traffic.”

The most common types of sensors will be battery-powered, with an emphasis on battery life. But they don’t have to be self-powered, as unpowered receiver-transmitter transponders also will do the trick.

“Wake-up” Sensors

“There is a new focus on sensors that will ‘wake up’ when you send them radio waves, measure conditions, transmit that data, and go back to sleep,” Chase told Better Roads. “These are best used for measurements that won’t change too much. But for conditions that are constantly under traffic, or wind loads, and continuous information is required, you will have to have a continuous power supply.”

‘Smart’ can apply to bearings as well. Smart bridge bearings take advantage of the fact that the distribution of live and dead loads to the bearings through the structural systems of the bridge can be used to diagnose problems.

Non-operating bearings and the tremendous stresses that result are a common factor in bridge failures and are a common maintenance requirement.

Multi-axis fiber optic strain sensors, capable of measuring both vertical and shear strains, are integrated into a composite panel. The panel then is laminated between the neoprene bearing pads commonly used on highway bridges, and will measure the vertical and lateral forces transmitted from and to the bridge.

Nanotechnology – and its application to bridge monitoring – constitutes the next frontier in smart structures.

Nanotechnology encompasses research, development and manufacture that utilizes and manipulates the unique properties of matter existing at the “nanoscale.”

At this length scale – approximately 1 to 100 nanometers, 1 to 100 billionths of a meter – clusters of atoms and molecules exhibit properties quite different from those found at larger scales. Thus, nanoscale science and engineering provide an opportunity to gain unprecedented insight into the unique phenomena existing at the nanoscale and to use that knowledge to engineer materials and devices with new characteristics.

With nanotechnology, super-small devices can be designed and manufactured to infinitesimal degrees of tolerance. Nanotechnology involves fabrication of devices with atomic or molecular scale precision, and at such a small scale, physical forces different from those of the ordinary human dimension are at play.

Today, nano- and micro-electrical mechanical systems (MEMS) sensors have been developed and used in construction to monitor or control the environmental condition, and the materials and structural performance. One advantage of these sensors is their small dimension; such sensors could be embedded into the structure during the construction process.

Larger than MEMS, “smart aggregate” has been used to monitor early age concrete properties such as moisture, temperature, relative humidity and early age strength development. The sensors can also be used to monitor concrete corrosion and cracking.

In a structural concrete matrix, smart aggregates can monitor internal stresses, cracks and other physical forces, and can be capable of providing an early indication of the health of the structure before failure can occur.

For example, researchers at Johns Hopkins University’s Applied Physics Laboratory developed a robust wireless embedded sensor suitable for long-term field monitoring of corrosion in rebar, particularly in bridge decks. These smart aggregate sensors can be embedded throughout a structure during construction, added to the mix right before placement. The smart aggregates are interrogated by a data reader that can be mounted on a car or truck; the transmitted energy from the reader excites the aggregates as it passes over them and collects their radiated sensor data onto a PC.

Each Johns Hopkins smart aggregate contains a wireless power receiver and data transmission coils, and incorporates ceramic hybrid integrated circuit technology to withstand mechanical stresses and concrete’s high pH environment. The aggregates are built to have a lifetime of 50-plus years.

“Nanotechnology will impact smart structures because the ability to manufacture sensors integrating nanotechnology gives us the potential to sense things that we could not in the past,” Chase said.

“For example,” he said, “there is work going on to develop chemical sensors that will serve as ‘artificial noses’, that can provide a very broad band of response to a variety of atmospheric gases. You can create a sensor that will be sensitive specific to a particular chemical, small enough that they will fit into a particular capsule, and mount that sensor on a structure. It then can tell you when the chloride ion concentration in the concrete has increased to the point where it might cause corrosion, but nondestructively, at a stage before there was any visible indication that damage had been done, with no inspector required to visit the bridge.”

Smart Bridges in Michigan

In early 2009, a new $19-million project on smart bridges was launched by the University of Michigan-Ann Arbor, with cooperation of the Michigan DOT.

The five-year project aims to create the ultimate infrastructure monitoring system and install it on several test bridges whose precise locations are not yet determined.

The monitoring system is envisioned to include several different types of surface and penetrating sensors to detect cracks, corrosion and other signs of weakness. The system would also measure the effects of heavy trucks on bridges, which is extremely difficult. And through enhanced antennas and the Internet, the system would wirelessly relay the information it gathers to an inspector on site or in an office miles away.

Funded in large part by nearly $9 million from the National Institute of Standards and Technology’s Technology Innovation Program, the project involves 14 UM researchers with the College of Engineering, and the UM Transportation Research Institute (UMTRI). In addition, engineers at five private firms in New York, California and Michigan are key team members.

The remaining funding comes from cost-sharing among the entities involved and the Michigan DOT. MDOT has offered unfettered access to state bridges to serve as high-visibility test-beds showcasing the project technology.

“This project will accelerate the field of structural health monitoring and ultimately improve the safety of the nation’s aging bridges and other infrastructures,” said Jerome Lynch, principal investigator on the project, and assistant professor in the UM Department of Civil and Environmental Engineering. “We want to develop new technologies to create a two-way conduit of information between the bridge official and the bridge.”

Four types of sensors will contribute to gathering data. Victor Li, professor of civil and environmental engineering, has developed a high-performance, fiber-reinforced, bendable concrete that’s more durable than traditional concrete and also conducts electricity. Researchers would measure changes in conductivity, which would signal weaknesses in the bridge. On test bridges, the deck would be replaced with this concrete.

A carbon nanotube-based “sensing skin” that Lynch and a colleague in chemical engineering are developing would be glued or painted on to “hot spots” to detect cracks and corrosion invisible to the human eye. The skin’s perimeter is lined with electrodes that run a current over the skin to read what’s happening underneath based on changes in the electrical resistance.

The sensing skin that Lynch and his colleagues created is an opaque, black material made of layers of polymers. Networks of carbon nanotubes run through the polymers. Carbon nanotubes are a fundamental building block of the nanotechnology revolution.

Each layer of the sensing skin can measure something different. One tests the pH level of the structure, which changes when corrosion is happening. Another layer registers cracks by actually cracking under the same conditions that the structure would.

The perimeter of the carbon nanotube skin is lined with electrodes that are connected to a microprocessor. To read what’s going on underneath the skin, scientists (or inspectors) send an electric current through the embedded carbon nanotubes. Corrosion and cracking cause changes in the electrical resistance in the nanotube skin. The microprocessor then creates a two-dimensional visual map of that resistance. The map shows inspectors any corrosion or fracturing too small for human eyes to detect.

Lynch says the skin could be a permanent veneer over strain- and corrosion-prone hot spots including joints on bridges, buildings, airplanes and even spacecraft. When it’s time to examine the health of the structure or aircraft, an inspector could push a button and in minutes, the skin would generate an electrical resistance map and wirelessly send it to the inspector.

Wireless Nodes

Also in the Michigan tests, low-power, low-cost wireless nodes could look for classical damage responses like strain and changes in vibration. These nodes would harvest energy from vibrations on the bridge or even radio waves in the air. They are being developed by Dennis Sylvester, an associate professor in the Department of Electrical Engineering and Computer Science, and Khalil Najafi, chair of the Electrical and Computer Engineering division.

The fourth type of sensor would be housed in the vehicles that travel on the bridge. UMTRI researchers will outfit a test vehicle to measure the bridge’s reaction to the strain the vehicle imposes. This information generally is not available today. But how vehicles, especially trucks, affect bridges is a critical piece of information that could help predict the structure’s lifetime.

Leading this effort is research professor Tim Gordon, head of UMTRI’s Engineering Research Division. “Our work will add to what is currently done, not replace it,” Gordon said. “The infrastructure problem and the feasibility of new monitoring strategies are emerging at the same time. We believe we have ways of testing the performance of bridges as integrated structures, not just inspecting their components.”

“The technologies from this project could prove very beneficial to the citizens of Michigan in the longer lasting, smarter, safer and ultimately more sustainable roadways,” said state transportation director Kirk T. Steudle, P.E.

Carbon Nanotubes at Work

Carbon nanotubes also will figure into two research projects announced in early April by FHWA. The project, under way at Florida State University, seeks to develop technologies to inhibit corrosion for new in-situ materials, and methods to repair or retrofit structures located both above and underwater. The research will utilize carbon nanotubes to develop an on-site spray-based method to develop both a structural capacity enhancement, and a barrier layer for corrosion resistance.

FHWA also issued a cooperative agreement for the University of Minnesota-Duluth to develop new, intelligent, self-sensing concrete pavement that can monitor its own structural health by continuously detecting internal stress level changes of the pavement. In the proposed pavement structure, the concrete will be mixed with carbon nanotubes, the piezoressitive property of which will enable the concrete to detect the changes in the mechanical stress.

Phase I of the proposed work will develop and test a prototype of self-sensing CNT concrete in a lab environment, and Phase II, which will be conducted in partnership of the Minnesota DOT, will fabricate and test the self-sensing concrete in a real but controlled road environment at the Minnesota Road Research Facility just north of Minneapolis.

Commercial Implementation

In the meantime, tried-and-true technologies like GPR are continuing to make their way into the field, but it’s only possible through improved technology.

“There are companies that will conduct a commercial GPR survey, and provide you with information that is based on more than just looking at echoes,” Chase said. “The work on phased array, on synthetic aperture, computer-aided tomography, and storing all this data on a computer and processing it to get information about what’s going on under the surface, all has evolved significantly in the last 15 years. A number of commercially-available systems have the capability of doing this type of signal processing, where it was not the case 15 years ago.”

And much more has transpired over the last decade-and-a-half. “The great thing is that simultaneous technological advances are making things possible today that weren’t possible just 15 years ago,” Chase said. “There have been tremendous advances in battery technology driven by the cell phone and wireless community that are now making it possible to have battery lives that are much longer than before. There also has been a focus on the development of low-power components, again, driven by the wireless technology industry, and they all have benefits for the bridge monitoring community.” v

by John M. Simpson, P.E., Transpo Industries

A successful slurry overlay project is the talk of Davidson County, Tennessee.

The Chickasaw Bridge, spanning the Ellington Parkway, was slated for four-day rehabilitation by contractor Jamieson Construction.

The bridge (named for a Native American tribe) required frequent patching. The Tennessee Department of Transportation (TnDOT) selected a polysulfide epoxy resin-based system for rehabilitating the aging surface.

The T-48 resists the effects of UV degradation, while the unique slurry application method allows for easy installation with minimum traffic disruption, Transpo maintains. The 3/8- inch-thick waterproof overlay adds minimal dead load to the structure (3 to 4 lbs/ sq ft), while the broadcast aggregate surface will maintain high skid resistance. With the reduction of permeability, there will be less rust and spalling.

With one lane of traffic open to the public, Jamieson Construction planned this bridge preservation project to take four days to complete. However, it was completed in just 12 hours.

Work began at dawn… and as dusk approached… the contractor decided that the project might be finished in a few more hours. Temporary lights were rented and work continued. The additional cost of the light rental was small compared to the savings realized in reduced labor and traffic control

The Chickasaw Bridge in Tennessee was finished in one day instead of the planned four days.

Project at-a-glance:

Material: Transpo’s T-48 Slurry

Location: Chickasaw Bridge, TN

Contract: Project #19960-4216-04

Size: 26,000 Square Feet

Application Time: 12 Hours

Owner: Tennessee DOT

Contractor: Jamieson Construction

Supplier: Hiwassee Materials, Charleston TN

With one lane of traffic open to the public, Jamieson Construction planned this bridge preservation project to take four days to complete. However, it was completed in just 12 hours.

Material: Transpo’s T-48 Slurry

Location: Chickasaw Bridge, TN

Contract: Project #19960-4216-04

Size: 26,000 Square Feet

Application Time: 12 Hours

Owner: Tennessee DOT

Contractor: Jamieson Construction

Supplier: Hiwassee Materials, Charleston TN

This article was written and contributed by New Rochelle, N.Y.-based Transpo Industries, Inc. Photos are also courtesy of Transpo Industries.