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Boardwalk and bridge bid delayed as structural engineer seeks clarity on flood height and liability
Summary
Beals and Thomas' structural engineer raised concerns about bridge height relative to the 100-year flood; the firm is consulting MWA and the committee said a hydraulic study could be required, delaying bids.
The Trails Committee said May 6 that work to finalize designs for the planned boardwalk and bridge — the next phase after paving — is on hold while engineers resolve questions about bridge height, flood exposure and liability.
Dave Lapointe of Beals and Thomas is coordinating with MWA to determine whether the existing controlled flow reduces the need for a new hydraulic study; the structural engineer said unresolved risk about debris and branch impacts could require raising the bridge or commissioning a study, which would increase cost and delay bidding.
“We may need a hydraulic study of the water level, but that's cost money,” a Trails Committee member said. “Spend another $10,000 that we don't have on a hydraulic study, which I don't know that we really need.”
Why it matters: the committee cannot issue a bid for the boardwalk and bridge until engineers and relevant agencies confirm the design meets safety and liability standards. Possible remedies discussed include a call with the structural engineer, consulting MWA for existing hydraulic information, or accepting design changes that could alter abutments previously reviewed by conservation commissions.
Committee members said the structural engineer’s primary concern is being comfortable that the design will not leave the engineer or the town liable if the bridge is damaged by floating debris or fallen trees. The unique local factor, the committee said, is that the waterway’s level is controlled by MWA, which could reduce peak heights; Lapointe is exploring whether MWA can provide data to avoid an expensive new hydraulic analysis.
Members said a design that raised the bridge enough to meet the engineer’s stated clearance could make the pedestrian structure higher than the adjacent road bridge and would also affect abutment details already approved by conservation commissions. The committee said it prefers the lowest bridge height that meets safety standards to avoid visual and structural conflicts.
The committee did not vote on budgetary changes or approve a hydraulic study at the meeting; members said they may schedule a group call with Beals and Thomas, the structural engineer and MWA to resolve the outstanding technical questions before proceeding to bid.
Background: the bridge and boardwalk design is part of the larger MassTrails-supported project. Committee members said they will pursue follow-up calls and report progress at the next meeting.
