The bridge, which is the only highway link between Hatteras Island and mainland Dare County, was shut down Tuesday afternoon because of concerns with scouring or sand erosion around pilings near the south end of the bridge.
The solution, NCDOT says, involves shoring up the pilings with concrete and sand.
“The technology we are using is something called concrete a-jacks,” explained NCDOT District One Engineer Jerry Jennings. “They are concrete modules that are interlocked together and will form a perimeter around the area that the scour has occurred.”
Once that is in place, sand can be pumped in to further solidify the support structure.
“We will go inside those and place large sandbags and completely fill the area and then do that again in two more layers. A layer of a-jacks and a layer of sandbags – and bring up the entire area that has scoured around the piles 10 or 12 feet in elevation,” Jennings stated.
“That will keep any additional scour from occurring but it will also help accumulate sand into those a-jacks, sandbags and around the pilings to support the bridge,” he continued.
The process is similar to repair work completed on another section of the Bonner Bridge in 2011.
“It was immediately north of the area we are concerned with now – going towards the high rise span,” Jennings said. “We have done very similar repairs on this bridge and they have worked.”
NCDOT says the 2011 work involved 3,824 a-jacks, whereas the proposed repairs for the current issues with the Bonner Bridge only require slightly more than 600.
Until the contractor is in place and able to assess the situation, NCDOT says they will not be able to offer a time-frame for getting the work completed and the bridge re-opened to traffic.