By Dustin Luca
---- — 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.
Mass. DOT Project Manager Matt Hopkinson said there will be no issues getting police, fire and rescue crews over the bridge in the event of an emergency in northern Andover.
“You’re putting a fire truck on a 10 foot lane. They may have to stop traffic or slow traffic down in order to safely travel through there,” Hopkinson said. “We looked at that and the folks at the safety complex seem to think they can work with that. We’ve addressed the safety issue. There should be none.”
“Opticom” traffic control technology used in public safety vehicles will also control traffic signals and cut off traffic flow to the bridge in times of emergency, according to Public Safety Officer Chuck Edgerly.
Sweeney Court residents, who access their homes through a driveway that essentially feeds right onto the south side of the bridge, will have a temporary entrance built for them while work on the northbound side blocks their normal entrance, according to Watters.
While the plans show years of forethought, there is still some need for more work, according to Selectmen Alex Vispoli. Central to his concerns is where the bridge merges two lanes of southbound traffic, heading towards downtown Andover, into one.
“When you’re coming up, it’s a little bit of chicken, of ‘Who’s going to get the right of way there?’ because it’s not really an ideal situation,” he said.
Addressing the concern, Watters said the bridge itself doesn’t get narrow on the southern end, but that the roadway is painted to merge the two lanes into one and turn a single northbound lane into two heading the other way. The
Construction is slated to begin sometime in 2014 after it goes out to bid later this year, Watters said. In a best case scenario, it could start next March and be done by the end of the calendar year, though inclement weather and delays could easily push the work into 2015.