First Street Bridge

Boston-Cambridge, MA

Market: Bridge


First Street Bridge

The First Street Bridge is a bascule drawbridge carrying traffic westbound over Broad Canal. The bridge suffered from several forms of deterioration including damage to the concrete counterweight, the concrete deck on the approach span, and the open metal grate deck. Under an on-call engineering service contract with the Metropolitan District Commission (now the Department of Conservation and Recreation), SGH prepared remedial designs and developed construction documents for rehabilitation of the bridge.

Scope | Solutions

As part of the historic waterfront, the overall appearance of the bridge cannot be changed. SGH conducted a condition assessment and performed a structural analysis of the complicated bridge type.

We provided recommendations for rehabilitation, including the addition of an unobtrusive roof to protect the counterweight, deck repairs that included the Land Avenue Bridge which carries eastbound traffic over the Broad Canal, demolition of the existing deteriorated counterweight, and replacement with a new hollow precast concrete, steel-supported, "false" counterweight respectful of aesthetic and historic integrity of structure.

Our work included preparation of plans, specifications, and an estimate for superstructure repairs including steel floor beams, stringers, and grating. We also prepared specifications for monitoring strains in counterweight support columns during demolition and a determined a live load rating of the rehabilitated bridge.

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