Paving the Brooklyn Bridge
The Right Mix, Crews, And Equipment Prove to be a Formula for Success
When New Jersey-based Asphalt Paving Systems Inc. (APS) was hired as a subcontractor to pave the Brooklyn Bridge during the summer of 2017, company president Ken Messina knew the project would present some unique challenges. It was the third time in Messina’s career that APS had provided micro surfacing as a pavement preservation project for this historic bridge. Between limited paving hours (with lane closures starting at 10 p.m. and ending at 5:00 a.m.); the cool, humid atmosphere; a tricky Type 3 mix; and double micro surfacing lifts of 28 pounds each — the opportunity for complications was far greater than with a typical micro surfacing job.
Built in 1883, the Brooklyn Bridge’s deck is constructed as a metal grid, filled with concrete and then surfaced with asphalt. Because of weight restrictions, the deck requires milling and micro surfacing every eight years or so to maintain the surface condition. It sees an Annual Average Daily Traffic (AADT) count of approximately 150,000 cars, so logistically, paving had to take place during nighttime hours. “The span we covered included three lanes in each direction, and it is approximately 3,500 feet across,” Messina explains. As the bridge was paved with a double lift, this translates to approximately 8 lane miles of paving over six nights.
Prior to laying down the new surface, the bridge lanes all were manually stripped of the old micro surfacing, and then they were shot blasted to ensure all of the old asphalt was gone, creating a clean surface for the new micro surfacing to adhere. Any repairs required by the bridge deck then took place. “At that point, the bridge was pretty much our baby for the rest of the project,” Messina says.
In The Mix
With the extreme traffic count for this bridge and the fact that it is a standalone surface, APS paved with a Type 3 mix design, in lieu of Type 2. “Type 3 has a coarser aggregate, with some larger stone in it,” says Messina. “Not all of the aggregates lend themselves well to a micro-surfacing with Type 3, which can create some complications with the mix designs.”
Nighttime projects create mix challenges of their own. “Compared to a daytime project, you don’t have the environmental factors of sun and heat helping the micro surfacing cure, so it’s an entire chemical break,” he says. “It’s the Brooklyn Bridge, so you’re over the river. You’ve got the humidity; you’ve got cooler temperatures; you’ve got the bridge moving pretty much the entire time you’re on it, because traffic is still able to have one lane going in either direction depending on where you’re working…” For this, APS worked with the emulsion and emulsifier producer to ensure a mix that would set up quickly, yet provide the required strength.
Each night of the project, starting at 10 p.m., approximately two hours of prep work was required to cover expansion joints and drain inlets before surfacing work could begin. “That’s where the unions came in,” notes Messina. “What we do is specialized, and the unions don’t necessarily have people trained in our field. Plus, this is a job where we’re using a larger than normal crew, and that time of year we don’t have people just floating around, everybody’s working. But we were able to get good union laborers to help us, and we taught them how to protect all of the utilities that were out there, and that includes the inlets, which were only 15 feet apart, and the expansion joints that have to move in between — that’s all got to be protected.”
In addition, because APS sourced its specialized aggregate from a quarry in central New Jersey, material transportation needs were high. “We were able to get operators out of the operating halls that kept the trucks loaded with material and moving to the project. Definitely, having reliable labor is key to a good project — on any project,” he adds.
Messina also credits the paving equipment APS used for contributing to the smooth success of the project. No new equipment was purchased, as APS used the tried-and-true Bergkamp Inc. M210 pavers that its crews were familiar with.
According to Messina, the M210 was ideal for the job for a number of reasons, not the least important being dependability. “We had a limited amount of time in which to have the road closed, prep work finished, and then surface, stripe, and open it in the course of a work night,” he says. “Bergkamp equipment is always dependable. Despite the dependability, breakdowns occur.The key to APS’s success is our relationship with Bergkamp. Their customer service is unparalleled, as reps are available 24/7, 365 days a year. This is vital to our business, as the Northeast has a relatively short paving season, and liquidated damages are always looming.One day of downtime can be a disaster on many of our projects.”
The truck-mounted M210 can carry 10.5 yd3 (8.0 m3) of aggregate in a level struck load, 600 gallons (2,271 liters) of asphalt emulsion, and 600 gallons (2,271 liters) of water. It features a 65-gallon (246-liter) stainless steel additive tank. The unit is powered by an onboard 99-horsepower Cummins diesel engine located at the front of the unit in an enclosed engine compartment that reduces noise for the driver and crew. It provides flexibility to better manage legal load weight restrictions by allowing up to three tag axles, including one behind-the-drive axle. This feature increases the wheelbase and helps the M210 meet the Federal bridge law.
Aggregate is delivered to the pugmill by a belt-over-chain conveyor that eliminates slippage. Steep hopper walls minimize bridging, while the hopper’s polyethylene lining reduces friction. This eliminates the need for a vibrator, which decreases problems with loose bolts and damage to welds and components. Asphalt emulsion is delivered to the pugmill by a positive displacement heat-jacketed gear pump. The pump is powered by a jackshaft that is common to the aggregate conveyor to provide a consistent asphalt emulsion-to-aggregate ratio. The variable-speed, dual-shaft, multi-paddle pugmill has a dual hydraulic drive, which provides even mixture and coating of the aggregate.
“With the M210, we got good mix action out of the pugmill, and we had really good coating on our aggregate, combined with a good mix design and a good emulsion. It was a great product at the end of the day. And the M210 keeps up very well with the speed of the pugmill. It put down a 28-pound application in one lift, which is really heavy for a micro, especially when it comes to a Type 3,” Messina says.
A Span of Emotions
The Brooklyn Bridge project was completed just prior to the July 4th weekend in 2017, and the significance of the date was not lost on the APS crews. Pictures of the project, with the crew and equipment, are proudly displayed in the APS front office in Hammonton, New Jersey.
Messina puts it this way: “You’re in New York City. You’re looking at the Brooklyn Bridge, knowing some history of it, and how many people died to build that bridge in 1883. And then you have the American flag on top of the bridge. When you look off to your left, there’s the Statue of Liberty. When you’re standing on the bridge, you’re about a half mile from Ground Zero. So then around the July 4th time that we were there, we were all thinking about our country and how great it is. To get a picture of the Brooklyn Bridge with that flag and our equipment in it was really surreal when you think about it. … It was a little bit emotional when I stood there. I got goosebumps.”
For more information on this project, click here to view the 2018 Spring Edition of the Pavement Preservation Journal.