December 4, 2013

DOT officials address Bonner safety
concerns at press conference in Manteo

By CATHERINE KOZAK



As transportation officials scramble to secure permits to repair the Herbert C. Bonner Bridge, they say that it is too soon to know how long the only land link to Hatteras Island will remain closed, but all indications are it could take many weeks or even months before work is completed.

At a hastily called press conference in Manteo on Wednesday, North Carolina Secretary of Transportation Tony Tata said that his seemingly abrupt decision to shut down the bridge yesterday was made after divers confirmed sonar surveys that showed alarming loss of supporting sand around pilings under one section of the span.

“Having nine of ten piles below critical level was the key factor to me to close the bridge,” Tata told reporters.

The secretary added that the unsafe condition of the bridge made it impossible for him to let people keep crossing the bridge, even though the lack of notice proved so inconvenient.

Tata said that he and Gov. Pat McCrory have each declared a state of emergency, actions that will hasten the permitting process for repair of the bridge. The department also plans to install new equipment to monitor the stress load of the pilings and the bents, or platform areas, of the bridge.

Over the last two weeks or so, Tata said, the state prepared a $1.6 million contract with Carolina Bridge Co. to address the increasing scouring that was detected by side-scan sonar. NCDOT and the contractor are working together to develop a timeframe for the repairs to be completed.

DOT says that as part of this emergency repair project, crews will use sandbags and four-foot tall A-Jacks to provide support to the bridge pilings. A-jacks locked together will be placed in a perimeter around the support structure of the bridge. Crews will then fill the perimeter with sandbags to provide support to the pilings.

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 protection. This will allow sand to collect over the sandbags and A-Jacks, providing additional support to the structure.

Tata said that in the last week, engineers reported that the sand depletion around the pilings was approaching a dangerous point.

On Tuesday, Tata said, they made the recommendation to him to close the bridge for safety reasons. At about 1:30 p.m., Tata said he ordered the bridge closed.

The problem is centered around Bent No. 166, located toward the south end of the bridge.

Jerry Jennings, NCDOT division engineer, said that pilings should be standing in sand 20 foot deep to be safe. The lowest piling has only 13 feet of sand surrounding it.
 
Jennings explained later that the sand creates pressure that holds the piling in place like rockbed would elsewhere. When the sand is scoured away to the currently dangerous low levels, the pilings could move, allowing the bridge span to tilt or leave the section with no underpinnings, which could cause collapse. 


“This is the worst situation that we have had in regards to scour on this bridge,” Jennings said at the briefing. “We have had other areas that have reached the point that we were concerned about. We were able to do repairs.


“But it never reached the point that the bridge had to be closed,” he said. “This is the first time it had to be closed because of this problem.”

Jennings said that it is “not completely out of the question” that the bridge may be able to be opened sooner to some traffic, with weight limits enforced.

But he said that engineers say that the “live loads” of traffic is not as much of an issue as the “dead load” –the bridge’s own weight – that is creating the concern.

 
“As soon as we reach a point in those repairs that the bridge can be reopened,” Jennings said, “obviously, we will make every effort to do that.”

Tata assured that the department will do all it can to mitigate the impact of the closure, including suspension of tolls for people traveling on the Cedar Island or Swan Quarter ferry.

“We care deeply about the people of the Outer Banks, as well as the environment of the Outer Banks,” he said.

Along with other local and state officials at the briefing, Tata lambasted environmental groups whose lawsuits have delayed construction of the bridge.
 
State Sen. Bill Cooke, R-Chocowinity, took a moment to thank DOT, and then called for the groups to back off.

“I’m not so grateful of the stupidity of what these environmental nuts are doing down here,” Cooke said. “This has got to stop. This is insane.”
           
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