MaineDOT bridge engineers are set to begin an intensive inspection of the Black Bridge, which is one of the four bridges that connect Topsham and Brunswick over the Androscoggin River. The bridge is expected to be closed for several weeks, as MaineDOT must build a staging area below the bridge in order to inspect the underside of the bridge.
The Black Bridge was closed Tuesday night after a vehicle crashed into the bridge?s steel suspension rods and pressure-treated guardrail. The steel suspension rods are the main support system for the bridge deck.
An initial inspection of the bridge showed little visible damage to the suspension rods. The suspension rods were also strength-tested last year and were found sound. Examination of the pressure-treated guardrail showed deterioration in the posts, prompting the need for a more intensive inspection.
The black bridge is an unusual bridge in that it is two tiers. It carries the Lewiston Lower Road rail line on the upper tier, and suspension rods attached to the rail bridge support a steel and wood lower tier that carries alternating one-way traffic over the river.
The pressure-treated wooden bridge deck and the pressure-treated wooden stringers that are on top of steel beams are similar in age to the guardrail, necessitating the inspection.
MaineDOT crews on Monday will start constructing a staging area that will allow them to inspect the underside of the wooden bridge deck.