Lynn-Saugus Belden Bly Bridge

Project Overview:

This bridge replacement project incorporates a Dutch-style bascule bridge, not commonly seen in the United States. The key benefit of the design is the overhead machinery room and counterweight which is protected from flooding due to the proximity of the roadway relative to high tide. The complicated bridge structure, counterweight and operating machinery will be fabricated, and shop trial-assembled at a single facility to ensure proper field assembly. The project scope also includes new abutments and retaining walls with driven pile foundations. The single leaf bascule bridge will be built over drilled shaft foundations with concrete piers.

Also included in the project scope is roadway and drainage improvements along Route 107 in Lynn and Saugus, MA and along Ballard Street in Saugus.  The existing temporary bridge will be removed during the final phase of the project, following traffic relocation on to the new bridge.

Key Challenges Overcome:

Construction of the bascule and rest piers over the Saugus River to support the new bascule bridge structure.  Drilled shaft foundations were installed in the river.  A concrete pier was then built around and attached to the drilled shafts.  All pier construction was performed from a trestle over the water.

In January 2024, SPS will commence a 4-month channel closure window when the bascule span will be built across the Saugus River.  The bridge structure and all operating machinery will be fabricated, installed and aligned as specified to extremely tight tolerances.

Interesting Facts / Figures

There were at least two previous bridge structures built in the location of this bridge.  Substructure remnants of the prior structures have been encountered throughout deep foundation and excavation activities.  Documentation of all prior structures does not exist.  The last bridge built in this location was constructed in 1912 and lasted long beyond it’s design life.

There is approximately 1,000 cubic yards of concrete in the bascule pier which supports the entire bridge structure when the bridge is in the open position.

There are 16 – 5-foot diameter drilled shaft foundations beneath the bascule pier which are drilled 20 feet into bedrock.

There is approximately 2 million pounds of counterweight used to lift the bascule span.