DOVER, Del. (AP) More than three dozen bridges in Delaware are considered structurally deficient, but state officials said motorists shouldn’t worry about a bridge collapse like the one that happened a year ago in Minnesota.
According to the state Department of Transportation, less than three percent of Delaware’s 1,473 bridges are considered structurally deficient, the fourth lowest percentage in the nation.
Delaware has only one steel deck truss bridge like the one that collapsed in Minneapolis, killing 13 people.
That bridge, on the Augustine Cutoff over the Brandywine Creek in Wilmington, is not considered structurally deficient. It received a thorough inspection in August 2007, and the inspection cycle was shortened to one year. A subsequent analysis of the bridge’s gusset plates in May of this year found no problems, and the bridge has been returned to a 24-month inspection cycle.
Delaware currently has 40 structurally deficient bridges, two more than at this time last year, but officials say 17 of those bridges are simply roads over pipes or culverts. Eleven structurally deficient bridges have been repaired or replaced in the past year, but 13 others have been added to the list.
Among the bridges identified as structurally deficient in the past year is the Newport viaduct in New Castle County, which carries more than 100,000 motorists on State Route 141 over the Christina River each day.
Permanent repairs to the Route 141 bridge are not scheduled until 2010, but DOT workers earlier this year made interim repairs to cracks in secondary supporting structures.
“[Even] if they were to fail, the bridge wouldn’t fail,’’ DelDOT spokesman Darrel Cole said.
“When you rehabilitate a bridge like that, a two-year time frame is pretty darn good,’’ he added.
Repairs already are under way on the most heavily traveled structurally deficient bridge in the state, on Interstate 95 over the Christina River. The bridge has an average daily traffic count of more than 128,000.
Meanwhile, work is expected to begin later this year on a replacement bridge over the Indian River inlet in Sussex County. Erosion of the seabed around the piers supporting the current bridge has mandated a replacement structure.
While structural deficiencies do not always render a bridge unsafe, six structurally deficient bridges in Delaware, including the Route 141 bridge, are considered “fracture critical,’’ meaning that failure of a main component could lead to failure of the entire structure. All of those bridges are on six-month inspection cycles, and weight limits have been imposed on two of them, with repairs expected on five of the six by 2010. The timing of repairs on the sixth bridge, on Northeast Boulevard over the Christina River in Wilmington, has yet to be determined.
Cole noted that if a deficiency involves the safety of a bridge component, the bridge is either closed or given temporary repairs until a permanent fix can be made.
“If a bridge were unsafe, it would be closed, period, end of story. That’s as simple as it gets,’’ he said. “We don’t have bridges like that in Delaware.’’