ANDOVER — State officials will use a Lego-like construction method for rebuilding a busy North Main Street bridge on the outskirts of downtown Andover to minimize traffic impact.
The state Department of Transportation is preparing extensive work on the town’s North Main Street bridge just south of the road’s Railroad Street intersection. The bridge, built in 1929, carries Route 28 over MBTA railroad tracks and connects downtown Andover to Shawsheen Plaza.
The latest estimates put the cost of rebuilding the bridge at around $3.4 million. Throughout construction, traffic heading both northbound and southbound will be unrestricted, according to John Watters, an engineer on the project.
“For the traveling public, there will be one lane of travel in each direction throughout all phases of construction,” Watters said. “There also will be one sidewalk throughout all phases.”
The project will replace every inch of the bridge’s “superstructure” — the steel beams and concrete layer that cars drive over. The “substructure” — essentially the walls holding the bridge up — will also see some work, according to Watters.
The project will run through an accelerated method where entire portions of the bridge will be built elsewhere and then brought to be pieced together in Andover, according to Watters.
Construction will be broken up into two phases, each phase handling one half of the bridge, Watters said. During each phase, a 10-foot wide travel lane will exist for each traffic direction.
One of the factors complicating the project is the fact that it passes over MBTA railroad tracks used by both passenger and freight trains. To remedy that, the work will be done during off-hours when train traffic is minimzed, according to Watters.
“This steel beam work I’m talking about is going to have to work either later at night when there’s shutdowns in the train service, or on some weekends when the train service is shut down,” he said.