The phone call would come at the worst possible time. A Friday afternoon. Spring Break. Peak of rush hour.
Small chunks of concrete were scattered across the travel surface of the Robert O. Norris Bridge, drivers were reporting. Cars, SUVs and tractor-trailers were slowing to a crawl to navigate the debris, usually right at the center line. Route 3 traffic was backing up into Lancaster and Middlesex counties from both bridge approaches.
As winter faded and spring crept closer, the Virginia Department of Transportation (VDOT) bridge maintenance crew grew to anticipate the emergency calls for service on Norris Bridge. Freezing and thawing cycles caused the concrete layer over the bridge’s structural steel grid deck to delaminate and break apart in sections. Usually, with awful timing.
Repair materials were staged and ready to go at all times, and crew members were on standby, but fighting through the congestion added to the repair time.
On one occasion, video footage of the concrete breakup surfaced on Facebook and was quickly picked up by a Richmond area television station. VDOT reassured drivers that the repair was similar to a pothole. The structural steel grid deck below the concrete overlay was sound, and the surface damage was only an inch or two deep. But the crumbling material remained an unsettling sight for travelers crossing the Rappahannock River at 110 feet over the water.
The two-lane bridge was built in 1957 and underwent a major rehabilitation in 1996. The bridge deck overlay was installed in the 1990s and was running up against its anticipated 25-year average lifespan.
VDOT’s maintenance and construction sections brainstormed a solution. The budget was fixed at $5 million in state maintenance funds.
VDOT needed a product that could be applied at this price point. But the curing time for concrete would be disruptive for residents in a region where the detour route to the next river crossing was 85 miles.
They landed on an idea: Rosphalt.
“We had done a section of Rosphalt on Norris Bridge that had performed well,” said Michael T. Coffey, P.E., VDOT Assistant District Administrator for Construction, Fredericksburg District. “We knew the product had potential, but we needed an industry partner that could properly prepare the deck surface and place the material at the proper temperature and density across the entire bridge deck, which is nearly 2 miles long.”
VDOT awarded the bridge deck overlay project to Allan Myers, one of the largest contractors in the mid-Atlantic and frequent VDOT partner.
“Rosphalt was a new product for us, but with our experience in the application of innovative materials in challenging situations on other projects, we knew we could make this work in partnership with VDOT,” said Chris Selph, Allan Myers Project Manager.
For the Rosphalt material to bond correctly, extreme cleaning methods were required. The area needed to be nearly dust- and moisture-free to achieve bonding to the concrete and metal bridge grate, requiring multiple cleaning cycles at more than two to three times the average. This additional cleaning time had to be added to the overall schedule to achieve timely completion.
In addition to the frequent cleaning, the density required for the material was extremely high at 98 percent or better of theoretical. This had to be achieved through the use of static mode on the roller to limit vibration on the bridge. To ensure compaction, a nuclear density gauge was used for testing instead of cores, but Myers did perform a few cores upon VDOT’s request.
The learning curve with the innovative material, coupled with the tight work space and load limitations on the bridge, required careful advanced planning and detailed orchestration by Myers.
“This was a unique project to plan. We had to perform load rating analyses to determine not just the weight, but how to distribute the loads by a piece of equipment and sequence their delivery by bridge span to meet the limitations. A full-time crew member was on hand at all times tracking and directing traffic,” said Craig Rayfield, Allan Myers Quality Control Manager.
Working 24/7 for seven weeks, Myers worked in nearly six-day cycles. Crews milled and cleaned for 3-4 days followed by paving and repeated this cycle until the full deck overlay was complete.
“Once we started, we really couldn’t stop, or we would lose momentum,” said Selph.
WORK ZONE CHALLENGES
Work started on July 5, 2018. The first several days were uneventful. But by the following week, as milling gave way to paving, travelers took to social media to report long afternoon delays, with a peak 45-minute wait to cross the bridge from Middlesex into Lancaster.
Paving equipment was working right up against the edge of the open travel lane. Drivers responded to pleas to use caution in the work zone, but the reduced 35 mph travel speed and the tight confines added to the backups.
VDOT began communicating which days crews would be paving, and which days crews would be milling. Drivers who had flexibility in their schedule were asked to choose another crossing on paving days and to avoid the peak 3-6 p.m. travel time to reduce their wait.
Another challenge emerged in mid-August when work was postponed for two days to allow an emergency bridge inspection. VDOT brought in an inspection crew to investigate an abnormal sound reported by a VDOT construction inspector working on the paving project. The inspection found the bridge to be in sound condition and safe for travel, and work resumed.
Despite these setbacks, the project was completed just before Labor Day weekend.
“We delivered a smoother surface for drivers, and thanks to the creativity and hard work of Allan Myers, the project was finished two months ahead of schedule,” Coffey said.