Groups slam temporary Charles River bridge

This story was updated at 2 p.m.

TO MAKE ROOM for a massive reconstruction of the Massachusetts Turnpike near Boston University, the Charles River Watershed Association said it would opt for shutting down Soldiers Field Road or merging it with I-90 instead of the state’s proposal to build a temporary bridge out into the Charles River to carry Soldiers Field Road, pedestrian, and bike traffic.

Other groups are raising similar concerns. The Metropolitan Area Planning Council is urging the state Department of Transportation to close Soldiers Field Road during construction or reduce it to one lane in each direction. The Conservation Law Foundation recommends reducing the size of the Turnpike in the narrow area between Boston University and the Charles River, going from four lanes in each direction to three lanes in each direction. The foundation and the Charles River Conservancy say another option would be to limit the Turnpike to three lanes westbound.

State Department of Transportation officials say the decision to run Soldiers Field Road out over the Charles River was dictated by the need for construction space as the Turnpike is lowered to ground level in the area; Soldiers Field Road is elevated over the Turnpike; rail lines are reconfigured; and sewer, water, and utility pipes are relocated. The whole process, with major focus on a narrow stretch between BU and the river dubbed “the throat,” is being called a second Big Dig and last nearly a decade.

Emily Norton, executive director of the Charles River Watershed Association, said the river also faces a new threat from the project. At a task force meeting last month, Norton said, state officials and their consultants displayed a rendering showing the Turnpike extending out over the river during construction. “The consultants explained to those in attendance that in order to accomplish this, additional fill and sheet pilings would be installed along the riverbank,” she said.

State officials initially said groups using the Charles River were supportive of a temporary bridge out into the Charles River, but, once concerns were raised, they defended the approach as the only viable alternative. At a public hearing of the MassDOT board, the project manager indicated the idea of reducing lanes for car traffic on either I-90 or Soldiers Field Road was impractical.

In a December 12 letter commenting on the state’s approach, the Charles River Watershed Association accused the Baker administration of springing the idea of a temporary bridge after most of the environmental review process had been completed and failing to consider alternatives. The fight over the proposed bridge is shaping up as a clash between environmental and transportation priorities.

The proposed bridge would break off from the existing section of Soldiers Field Road about 330 feet west of the BU Bridge, rise on fill to a temporary bridge on pilings several feet above the water, and then return to shore further west down the river. The bridge, along with pedestrian and bike paths, would be about 50 feet offshore, a quarter-mile long, and about 80 feet wide. It would reduce the width of the Charles River in that area from 500 to 370 feet.

“The fact that such fill, pilings, and other materials may not exist in in the river permanently does not mean that the environmental impacts associated with placing them in the river and then subsequently removing them will not be permanent,” the Charles river Watershed Association said in its letter.

The potential impacts of the bridge could include disruption of contaminated sediments on the river bottom, degradation of water quality, and damage to aquatic life, the association said.

The Charles River Watershed Association says the best way to come up with space for the construction work would be to reduce the number of temporary roadways available during construction. The association recommended combining I-90 and Soldier’s Field Road traffic on one roadway or eliminating Soldiers Field Road entirely during construction.

“Diverting Soldiers Field Road traffic onto I-90 or closing it during construction would not only avoid negative impacts to the river, it would also avoid significant costs, allowing public funds to be put to better uses like improving public transit, restoring the riverbank, and enhancing public parkland along the river,” the association said.

Other groups favor permanently narrowing the Turnpike in the constricted area. The Conservation Law Foundation, in a December 12 letter, called for three Turnpike lanes in each direction or four lanes eastbound and three going west. The foundation said tolling data indicate only three lanes are needed going westbound.

“Eliminating one lane on the Westbound I-90 could have significant advantages including space to maintain two-track commuter rail service throughout construction, reduced impacts on the Charles River during construction, [and] expansion of the narrow riverside park in the final build condition,” the foundation said in its letter.

The state Department of Environmental Protection also submitted a letter that urged state transportation officials to more fully explain why they think building a Soldiers Field Road bypass out in the Charles River is the preferred construction option.