Further, the SELC claimed the same ocean scour and barrier-island problems plaguing the Bonner Bridge also will affect the planned replacement structure, "and the people of Hatteras Island will continue to be stranded by NCDOT's poor planning for decades to come."

NCDOT's Jennings says the design for the replacement structure will address Oregon Inlet's scour dynamics.

"Extensive scour modeling was performed to determine the maximum scour depths that would be anticipated, and the substructure was designed to accommodate these depths," Jennings says. "The new bridge will have pilings significantly deeper than those on the existing bridge."

For now, NCDOT is going ahead with other projects aimed at reducing Route 12's vulnerability to the elements. In early December, the agency awarded a $79.7-million contract to Parsons Construction Group Inc., Greenville, S.C., to construct a 2.4-mile bridge that will replace a temporary steel span erected when, in August 2011, Hurricane Irene's storm surge cut a new inlet into the narrow barrier island. Designed by STV/Ralph Whitehead Associates Inc., Charlotte, N.C., the new bridge will feature support piers that provide 15.8 ft of clearance above the mean high-water level at the span's highest point.

The project could face a court challenge because the structure's location on the coastal side of Route 12's existing right-of-way may eventually leave it in the Atlantic Ocean surf.

NCDOT is also eyeing a bridge to address another Route 12 trouble spot, just north of Rodanthe. Two options—a 2.3-mile bridge within the existing Route 12 easement or a 2.6-mile-long bridge extending into Pamlico Sound—are under consideration, and the agency hopes to award a construction contract in the spring. A beach-nourishment project, developed with the Corps of Engineers, is designed to protect the area from overwash during the expected three-year construction phase.