Despite six-month fish moratoriums, construction of a 3,200-foot-long bridge connecting Carteret County a North Carolina Direct to Harkers Island has been completed a year ahead of its original schedule.
Demolition of the original Earl C. Memorial Bridge, a steel cable-stayed bridge, will be completed this month, while Bridge No. 96, which continued the connection past a causeway from the fishing pier, is being repurposed as a pedestrian bridge to provide access to downtown. island and a renovated strait fishing pier.
The new fixed-span bridge, built over the straits to the east of the two 50-year-old structures, provides a direct route for drivers traveling there from the mainland. With a navigation distance of 45 feet, it allows boats to pass unimpeded and allows motorists to travel safely without waiting for bridges to open which can take up to 15 minutes.
The structure has carbon fiber reinforced polymer (CFRP) strands and glass fiber reinforced polymer (GFRP) bars to better withstand the coastal environment. “A few years ago we had to replace all the core slabs because of salt water and corrosion” on the drawbridge, says Brad McMannen, project manager for the North Carolina Department of Transportation. “The concrete was falling and the [swing span] was closing From a maintenance point of view, it was time to do something new and different.”
Balfour Beatty won the $68 million job in the fall of 2021. “Once we got to the site, we talked about the [possibility] to finish a year ahead of schedule,” says Mark Johnnie, CEO of Balfour Beatty US Civil.
The contractor engineered the value of the pre-drilling process to speed up the schedule, says Peter Distefano, Balfour Beatty’s senior project manager. To eliminate the need to perform a full excavation prior to pile placement, the team tapped a probe through approximately 5 feet of overburden. “The borings showed a fairly soft layer underneath,” he says. “Essentially, excavating the pile required a 42 in. casing to be installed to drill. So we took that casing and modified it into a probe. We used that to vibrate through the layer” .
Shipping the 28 concrete beams by barge instead of by truck also saved time, as well as adding extra shifts. “The lease was at the end of July and we were awarded the job at the beginning of August,” recalls Distefano. “The moratorium started on October 1. We had to get up and running quickly and push the production pile-up and easel stacking in the two months in between,” he says.
He adds, “We had a pretty strong workforce in the area. We had just finished the Surf City Bridge south of that project, so we had a lot of good crews ready to go.”
Due to the design of the bridge with CFRP and GFRP materials, there were strict requirements that did not allow any ferrous material in the construction of the bridge. “We used friction collars on the piles to support the concrete substructure,” says Distefano. “A lot of outside support was needed in terms of forgery.” The bridge bearings and anchor bolts are stainless steel, adds Johnnie.
Tearing down the old rope-slab-style bridge is “a pretty simple process,” Distefano adds. “We have two cranes on two barges: one crane working the center pivot dock area, the second working the approach legs and rope slab sections.”
The new bridge, which McMannen says carries about 3,500 vehicles a day, opened last December with significant community involvement. “It’s remarkable how they supported the construction,” Johnnie says, noting a Facebook fan page and locals bringing food to the crews. “It was something to see.”
