Highway Contractor: A hard day's night paving
Better Roads Staff | June 1, 2010
According to equipment industry leaders, successful paving projects at night start with three things: planning, planning and planning.
By Mike Anderson
Working all night” may sound like a long, drawn-out sentence for anyone punching a clock. For a paving crew, it’s anything but, warns veteran industry trainer Terry Humphrey.
Always a critical factor in construction success, time management is even more so when paving at night, says Humphrey, a retired Cat Paving training manager now serving the company’s dealers and customers as a vendor-employed training consultant. “Night paving always has a requirement that we lay a certain amount of tons in a prescribed amount of time,” he explains. “Traditionally, during the daytime, we would think about, ‘Well, I’m going to lay 2,000 tons in this shift; it may take me eight hours, it may take me nine hours, but I’m going to lay 2,000 tons.’ At night, you’re planning maybe to lay 2,000 tons, but you have a fixed starting time and a fixed stopping time. So, time management on the paving process is a big difference.”
His advice? Plan, plan, plan! “You just cannot lose time,” says Humphrey, “because you’ve got no way to make it up in the middle of a shift. The time management gets tougher at night, for sure.”
Having been put to practice in various parts of North America for 30 years now, night paving is established, continually expanding, and certainly not going away, says Bill Rieken, paver applications specialist with equipment manufacturer Terex Roadbuilding. “It’s just a reality we’re in. With the traffic loads we have today, a contractor’s going to have to plan on night paving,” he says. “Even here in the Midwest out on the Interstates, we’re paving at night.”
Paving contractors, when working at night, need to have their ducks lined up even more straight than normal, concurs Rieken. “You’re on and off the road in a certain timeframe, so you’ve got to make sure all your equipment’s working properly and that you don’t have breakdowns,” he says, “and that you’ve got a plan in case there is a breakdown. You’ve got back-up equipment; you’ve got something in place to deal with whatever might happen on the jobsite, so that the traffic is opened back up on time. Usually there is a time deadline: by 6 o’clock, 7 o’clock or whatever it is, you’re finished your work, you’ve cleared your cones and the lanes are opened up.”
Or else you pay, says John Sunkenberg, a road industry product competency manager for Volvo Construction Equipment. “Because there are traffic constraints that have triggered this to be a night paving job, there’s usually a time constraint when you have to get off the job. So if a piece of equipment is down, or something else is down, you’re going to start getting fined a big fine hourly if you’re not off the road in the allotted amount of time.”
To accomplish all that’s required in a night shift, “job management is critical,” says Rieken.
Worth repeating. And repeating.
Humphrey makes no apologies for being a broken record: “Planning, planning, planning,” he stresses.
“Traffic control is a huge problem with night paving, because it’s most always urban paving, specifically a multi-lane situation where you’ve got live traffic in the same direction as the paving crew,” he says. “Traffic control is totally different at night because of the lack of visibility. The key is pre-project or pre-shift safety meetings that explain to everybody where traffic is going to be at all times: which lanes are closed; which lanes are open; how close will the traffic be to the cones or the barricades that are set up. Communication about safety becomes even more critical at night.”
When it comes time to lay material, “we can’t afford to make any mistakes, because of this time thing,” says Humphrey. “Everybody has to be a little bit more vigilant at night, and it starts at the plant. We don’t see as well, we’re not going to see defects in the material, so the plant really has to have excellent quality control at any time but at night it’s even more critical. We have to be able to depend on that mix coming to us the same, truck after truck.
“At night, you’ve got no time to recover from mistakes.”
Among the “over-planning” or preparing for contingencies Humphrey recommends for consideration is an extra truck or two to avoid unnecessary waits. An extra roller may be needed, too. “Because the ambient temperatures are different at night, in other words it’s cooler at night, the mix is going to compact differently,” he says, noting the need for quicker compaction of the faster-cooling material on a night Superpave project. “Instead of having one compactor, you probably need two compactors ahead of the tender zone.
“When I work with the crews at night, I do cooling curves that tell me how long I’ve got before the mat cools to a certain temperature. That tells me: if I’m paving this wide, laying this many tons, I need this many compactors. It’s just getting information, and sharing that information, because the plan you make at night is different than what the crew is used to doing during the day.”
At the paver itself, “it’s mainly the visibility issue,” says Humphrey. “The mix goes through the paver the same way, grade and slope control operates exactly the same way, it’s just that people can’t see as well. For example, the operator may not be able to see his steering guide with we’ll just say conventional balloon lights on a paver. We may have to take a separate light – a spotlight – and focus it on the steering guide, so that the operator can clearly see that when matching a joint.
“We may also want to have a light that shines directly into the auger chamber, so that the screed operators can clearly see the head of material. They’re trying to control that to cover one-half of the auger and fill-in in front of the extension to make sure there are no voids,” he says. “Typically, that area is kind of dark even with conventional lighting, so a spotlight in that area is very helpful.”
It’s always a challenge, says Volvo’s Sunkenberg, for equipment manufacturers to keep up with lighting requirements that vary by jurisdictions. Or, as Humphrey puts it, “sometimes the local requirement for lumens actually gets in the way of clear visibility.” Personally a fan of the inflatable balloon lights that can be attached to the paver or stand alone, Sunkenberg has seen scenes throughout the country that range from a single light fixed to a paver, to long rows of portable lights stretching many thousand feet up and down the road, to ballasted high-intensity “warehouse” lights literally blasting harsh brightness onto the job. “I’d say more often than not, contractors are building their own, customizing their own,” says Sunkenberg, whose company does offer a lighting kit for its paving equipment.
He doesn’t sell balloon lights, but Terex Roadbuilding’s Rieken is likewise a fan, “because they are so easy to attach to the paver, they don’t glare and they just light the world up. They inflate when you plug them in, and I just think they’re slick,” he says. “I don’t have any stock in them, I don’t sell them; I just like them. I just think they provide a really good lighting system on the paver itself. With other lights, you’ve got to be careful how they are aimed, so that they don’t create a glare, not only for the people on the jobsite, but for anybody driving by. The balloons light the world up without that glare, so I’ll give them a plug,” adds Rieken, specifically mentioning the Airstar brand of balloon lighting products.
“The facts that balloon lights are glare-free, shadow-reduced, portable and that they spread their light all around in a 360-degree circle make them so popular,” says Ingmar Hansen, vice president of Powermoon Enterprises Ltd., a company which offers a line of modified balloon products. An “umbrella system” is designed to prevent the Powermoon lights from accidently deflating, says Hansen.
Along with the more uniform heating of the new electric screeds available on pavers, “there’s power on board at the paver to light the world up around the paver itself,” says Rieken. “We designed ours knowing there would be a lot of night paving going on. The rule of thumb is that it takes about 1 kW per foot to heat a screed, so on our Stretch 20 screed we have a 34-kW genset. So, you can add extensions and go wider, up to 26 feet if you choose, but still have plenty of kW left to have the lights on at the same time you’re heating the screed.”
Especially when working with high-intensity lights, the powering of lighting systems at the paver is an issue that equipment manufacturers have had to deal with, says Volvo’s Sunkenberg. “We need a very stable, consistent power source, which on a machine is difficult because you have horsepower fluctuations, or the engine lugs down, or you have hydraulic surge and hydraulic delays. It’s certainly a challenge from an equipment standpoint,” he says. “Our highway-class machines have outlets as standard equipment. You can boast that you’ll plug other things other than lights in there, but 99 percent of the time that’s what they’re there for. Occasionally, a guy will plug a power drill in because maybe he doesn’t have a service truck right there and he’ll use the paver outlets for alternative power, but it’s really for night lighting.”
Man with a plan
Saving a few minutes a few times over a night shift is really what the intricate planning Humphrey espouses is all about.
Case in point: “Vibratory compactors typically will need to resupply the water spray system once during the shift. If I’m going to refill the water spray system in, let’s just say, five hours, I want to know where I’m going to be on the project five hours from the start, and that’s where I’m going to have my water truck waiting,” he says. “I don’t want to need to have somebody run back to the start of the job and bring the water truck up to that point. I want to have it there already. It’s a small detail, but maybe that saves you 10 minutes. Those are the things I’m talking about – this planning, planning, planning.”
Not only adding a truck or two to the job cycle, but when to have them can be a timesaver, says Humphrey, citing a three-lane paving job in which the high-speed lane is paved for 1,500 feet, the crew then picks up, backs up and completes the middle lane for the same distance, and then ditto for the right lane. He calculates that 18 trucks hauling an average of 22 tons are going “to get me this distance. What I’ll try to do is make sure that I’ll have those 18 trucks show up to me in a tightly staggered pattern, so that I don’t have any stops – zero stops – especially during that first lane pull. I might gain a little bit on my production the first pull. I’m really going to try to plan that I have enough trucks to get me through that first pull without ever having the possibility of a stop.”
The theory, says Humphrey, is to get through the first third of that particular phase of the project in less than one-third of the phase’s allotted time. “I balance plant output, trucking, paving speed and compaction, so that in that first pass, I can go as fast as I can get the mix to it, without stopping and without outrunning the compactors. Then I’ve got myself a little breathing room moving forward.”
The vehicle volume factor
Ironically often the political reason for paving at night, reduced traffic, actually represents an advantage to efficient night paving, “because the traffic is what really hinders continuous paving,” says Terex Roadbuilding’s Rieken. “During the day, you might have a plant that has sufficient production, you might have adequate trucks, but the traffic still might hinder the flow of trucks to and from the jobsite, so the night paving if anything probably lends to the success of the continuous paving process, because there is less traffic.”
Says Humphrey: “The paver itself doesn’t care how fast you pave, as long as you’re consistent and don’t have long stops … and the compaction process can match you. So, you plan all that before you go to work. You make the calculations.” Adds Sunkenberg: “If you’re on a continuous paving job at night and the paving train stops, they’re upset, because the profilograph will pick up a stop and it will count against their final score and will ultimately cost them money.”
On the con side of the night paving equation is increased cost, says Rieken. “To ensure the safety of the paving crew and the operation, and of the people driving on the road, it takes more people, more equipment to make that happen, so there is a cost incurred that would probably be the biggest downside of doing it at night.” Which leads to another suggestion from the veteran trainer Humphrey: “Fatigue plays a huge role in night paving. I’d suggest trying to figure out a way if I can overstaff by one person. ‘Can I give people a chance to actually stop work for a minute, get a cup of coffee and stagger out a little bit, so they don’t get quite as fatigued, lose their focus, because that’s when mistakes happen?’
“If you have a long night project, I think you’re almost better off having one crew doing it instead of switching crews on and off nights,” says Humphrey, “so they might have a chance to acclimate to working at night and resting during the day.”
A safe work environment – and Sunkenberg has worked with night paving contractors who ensure reflective tape is wrapped around anything and everything on site – is the only thing that ultimately matters, says Humphrey.
“The residents, the business owners, nobody likes to have construction going on,” he says. “I’m not too sympathetic to that.
“We have to be able to see out there … and we’re going to make a certain amount of noise.” v