Oops! Support piers uneven for American Tobacco Trail footbridge over I-40

bsiceloff@newsobserver.comMarch 27, 2013 

— Massive concrete support piers for a $7.5 million footbridge over Interstate 40 will have to be cut down to size next week, because project engineers noticed recently that they had been constructed two-and-a-half feet too high on one end of the bridge.

“Oh, no,” said Curt Devereux of Durham, president of the Triangle Rails-to-Trails Conservancy, when he heard the news. “If they used it that way, the bridge would not be as level as they want.”

It’s the latest in a years-long string of mishaps and delays for the 800-foot-long bridge. It’s part of a 4.2-mile section of the American Tobacco Trail in southern Durham County that is still scheduled to open in July.

The piers are huge underground cylinders of steel-reinforced concrete, four feet in diameter, rooted in bedrock 50 feet below the highway. Workers discovered in mid-March that the tops of all four support piers on the north side of the bridge were built higher than called for in the bridge plans.

“They were getting ready to pour the (concrete) beam that sits on top of two of those piers, and that’s when they figured out they were too high,” said Ed Venable, a Durham city public works engineer managing the project.

He blamed a surveyor’s error and said the builder, Blythe Construction Co. of Charlotte, will bear all costs for correcting the mistake.

The repair is straightforward, Venable said: Cut off the top two-and-a-half feet.

Next week, workers will use a concrete saw to mark the proper height on each column.

“They’ll cut a groove all the way around it, then use a jackhammer to remove all the concrete above the groove,” Venable said.

“It’s a pretty easy fix. The hard part was all the engineers who had to scratch their heads and realize, yes, that’s an appropriate way to handle that. It just takes time to roll through those calculations,” he said.

After the supports are in place on both sides of I-40, workers will assemble the steel deck for the single-span bridge on the roadside. All traffic on I-40 will be shut down for a night while a crane lowers the steel deck into place, onto the support piers at both sides of the highway.

The bridge project is running about two months behind schedule, Venable said. He had planned to put the steel deck in place in February, but that won’t happen now until April.

“The overall schedule is getting everything done by July,” Venable said. “I don’t believe that schedule is in jeopardy, yet.”

Devereux’s group, the Rails-to-Trails Conservancy, has been pushing to get the bridge built since 1999. It’s a key part in the final link of the 22-mile American Tobacco Trail from downtown Durham to New Hill in Chatham County.

Problems with financing, design, permits and other issues have slowed progress since the project cost was pegged at $650,000 in 2000. Construction started in 2012.

“This thing has just had comedies of errors and delays ever since the money was appropriated in 2005,” Devereux said. With the final section, the trail will carry hikers and bicyclists through the Woodcroft neighborhood on the north side of I-40 and around the Streets at Southpoint mall on the south side.

Steve Schewel, a Durham City Council member, said he had not heard about the surveyor’s mistake. He said Durham residents are eager to see the bridge finished.

“The day that’s done, there are going to be people on bikes and on foot who are going to be pouring across the bridge in both directions, enjoying themselves,” Schewel said. “The sooner the better.”

Siceloff: 919-829-4527 or blogs.newsobserver.com/crosstown or twitter.com/Road_Worrier/

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