Area bridges face safety upgrades following concrete collapse

  • Workers install wooden shielding on the bridge over Interstate 93 at Exit 4 in Londonderry on Monday after debris fell from the bridge. Courtesy NHDOT

Monitor staff
Thursday, August 31, 2017

Four bridges in Concord and one in Bow and Warner, all built before 1982, will have shielding installed this fall because they have the same design as a bridge over Interstate 93 in Londonderry, where a chunk of concrete fell onto the road Monday.

The bridges are among 16 on the state’s Red List of bridges in poor condition that will be inspected on an accelerated schedule. They all have concrete “haunches,” approximately 4 inches wide, located alongside the flanges of the metal support beams. One of those haunches fell from the Route 102 bridge over I-93 Exit 4 on Monday, shutting part of the highway.

No one was injured, officials said, but the accident has led the state Department of Transportation to inspect all Red List bridges and remove any haunches or material that appears in danger of falling. They will also hire contractors to install shielding in the form of netting or wooden structures to catch any future falls.

“We expect this shielding to be in place at all of these bridges, tentatively by the spring of 2018,” said Bill Boynton, spokesman for the DOT.

Boynton said haunches have not been part of the design of any bridge built since 2002.

All Red List bridges are inspected twice a year, as compared to every other year for the rest of the state’s bridges.

The bridge that lost a piece Monday was built in 1962 and is being replaced next year. “This location is an active construction site, that includes blasting in the area,” Boynton said.

(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com.)