The New Hampshire Dept. of Transportation began rush inspections of 16 deteriorating bridges on Sept. 6 after a large piece of concrete fell off the N.H. Route 102 Bridge onto moving traffic on I-93 in Derry, N.H. a week earlier. The so-called "red-listed bridges" have at least one major element classified as being in poor condition.
"Using an abundance of caution, the NH DOT will be evaluating if there is a potential issue with other bridges with a similar feature," says Bill Boynton, a spokesman for NH DOT.
No injuries were reported after the concrete fell off the Route 102 Bridge on Aug. 28 but at least one car was damaged after driving over the shattered concrete near Exit 4. The red-listed bridge was built in 1962 and will be replaced in 2018 by a new bridge being constructed nearby as part of the $49 million I-93 widening and reconstruction project between Exit 3 in Windham and Exit 4 in Derry.
After the concrete fell, the general contractor for the new bridge, R.S. Audley, installed lumber under the old bridge to prevent more concrete from falling, Boynton says. “The piece that fell was not critical to the structure of the bridge,” Boynton says.
The NH DOT inspects state bridges every two years, and red-list bridges are inspected twice a year. But after the incident, the department identified 16 red-list bridges with decks in poor condition that will be inspected by bridge maintenance crews who will remove any loose concrete. In addition, the department will be putting out a contract to install protective shielding underneath those 16 bridges, similar to what was done at the Route 102 bridge, Boynton says. “We expect this shielding to be in place at all of these bridges by spring of 2018.”
During a systematic evaluation of existing bridges with the same concrete feature, the department will gather information to help inform whether anything additional needs to be done.
State officials also took steps over the summer to repair the state's deteriorating bridges. Unveiled last month, a draft of the state’s 10-year transportation improvement plan calls for repairing 135 of the 140 state-owned, red-list bridges by 2028.
Furthermore, a bill passed by the Senate on July 12, allocates money from New Hampshire’s budget surplus to local highway infrastructure projects. Red-listed bridges were also redefined earlier this year to include only bridges given a “poor” rating or below on the national bridge index. Previously, bridges given a “fair” rating were included on the list.