RALEIGH —N.C. Department of Transportation crews today conducted several tests and surveys of the Herbert C. Bonner Bridge on N.C. 12 over the Oregon Inlet in Dare County. These tests allowed the department to gather crucial information to help evaluate the overall effectiveness of the sand placed in the area where erosion occurred and determine the next steps for repairs. Results of the information gathered today should be available Thursday. Photos of the various activities conducted at the bridge can be found on NCDOT’s Flickr site.
As part of today’s testing, crews with NCDOT’s Location and Surveys Unit conducted an underwater sonar survey of the area around Bent 166. Dive crews also inspected the area to assess if the sand is compacting as it needs to in order to properly support the bridge.
The department also began testing how much weight the bridge piles can carry. Carolina Bridge Company Inc. will drive two test piles into the inlet floor near the general vicinity of Bent 166. As of 4:30 p.m., they had completed one test drive.
NCDOT’s geotechnical staff will use the data gathered today, as well as additional surveys, to fully assess this situation and future repairs. Once a full assessment of the bridge’s safety is complete, NCDOT will determine the next steps. According to NCDOT Division 1 Engineer Jerry Jennings, the timeframe for reopening the bridge could be about a week from now or up to 90 days, depending on the findings of the assessment and timeline for repairs.
Approximately 30,000 cubic yards of sand were pumped during the weekend from the main navigation channel of the Oregon Inlet to the location at Bent 166 underneath the Bonner Bridge where scour, or the erosion of sand from bridge pilings, caused NCDOT to close the bridge on Tuesday, Dec. 3.
NCDOT awarded a $1.6 million contract to Carolina Bridge Company Inc. of Orangeburg, S.C. last week for emergency repairs on the Bonner Bridge.
Crews will use sandbags and four-foot tall A-Jacks to provide support to the bridge pilings and prevent further scour from occurring. A-Jacks interlocked together will be placed around the perimeter of the support structure at Bent 166. Crews will then place sandbags inside the line of A-Jacks. An additional two layers of A-Jacks and sandbags will then be placed on top of the base layer for a total of 10-12 feet of additional protection. This will allow sand to collect over the sandbags and A-Jacks, providing additional support to the structure.
Contractor crews have begun mobilizing equipment and materials to the bridge site. NCDOT and the contractor are working together to develop a timeframe for the repairs to be complete.
Emergency Ferry Route
NCDOT’s Ferry Division activated its emergency route between Stumpy Point and Rodanthe with limited service the night of the bridge closure. The route went into full operation Wednesday, Dec. 4, with steady traffic and short-to-moderate wait times reported at both terminals. Dare County Emergency Management has issued a priority loading list for the route. The emergency ferry route will continue seven days a week as long as service is needed. Ferry information is available on the Ferry Division website, by calling 800-293-3779, or via Facebook and Twitter at @NCDOT_Ferry.
For More Information
NCDOT will continue to update the public on this situation online and via its N.C. 12 Facebook page and N.C. 12 Twitter account.
While NCDOT is working hard to reopen the Bonner Bridge to traffic as quickly as possible, the emergency repairs are not considered a permanent fix for the aging bridge. After 50 years of weathering many storms, the bridge needs to be replaced. In July 2011, NCDOT awarded a $215.8 million contract for the design and construction of a new bridge. Design work began immediately and construction of the new bridge was set to begin in early 2013; however, lawsuits have put the project on hold.
Read more about the history of the Bonner Bridge and the challenges to replacing this lifeline.
(Editor’s note: Images of A-jacks are available at: http://www.flickr.com/photos/ncdot/6377484269/. These photos are from a scour prevention project at another span in 2011.)
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