The Northeast Corridor (NEC) is a crucial rail line serving passenger, commuter, and freight traffic from Boston to Washington, D.C. Many of its bridges, including the Norwalk River Railroad Bridge (also known as the WALK Bridge), are over a century old. Built in 1896, the WALK Bridge is a 564-foot steel truss bridge with four tracks and a 202-foot swing span. One of the oldest movable bridges in the region, the structure has outlived its useful life and is now part of the Connecticut Department of Transportation’s (CTDOT) effort to enhance rail and infrastructure through the WALK Bridge Program.

To prepare for the bridge replacement, Cianbro began working in 2014 in a joint venture with Middlesex (CMJV), serving as general contractor while working with the state on the preconstruction phase of the new dual lift span bridge.

CMJV has erected four trestles, restored a wetland site, treated six wetland sites for invasive species, installed a water treatment plant, and developed laydown and access yards surrounding the bridge as part of the scope of work. The lift span pier foundation work consists of eight 12-foot diameter drilled shafts utilizing four temporary work platforms. Four 10-foot diameter micropile clusters will be installed using two other work platforms under the existing bridge via a cantilever rigging system.

Most of the foundation work has been done with minimal clearance to the existing bridge while it remains operative. A key aspect of the project is the installation of two 6-foot micro-tunnels bored using two secant pits on either side of the river. These tunnels will house the overhead utilities, enabling CMJV to demolish current structures and erect new ones without interrupting rail service.

The scope also involves replacing four local bridges and upgrades to the East Norwalk Train Station. CMJV is performing this work in conjunction with the Advanced Utilities Project, which started in 2019. Early procurement of bridge steel, mechanical equipment, and establishing the Manresa Yard for prefabrication activities is underway. The construction of the approaches, bridges, piers, and towers continues, with the float-in of the two 240-foot lift spans targeted for late 2030.

The project totals 9,500 tons of steel, 1,200 tons of rebar, and 6,500 cubic yards of concrete, resulting in a dual-span lift bridge that will be 160 feet tall.

The CMJV team is leveraging services across both organizations to deliver effective solutions. Cianbro’s construction structures group has designed temporary trestles and platforms that reduce impacts on rail operations. Additionally, the team has secured specialized equipment and rental contracts to enhance efficiency and collaboration.

Located in downtown Norwalk, with a large population relying on Metro-North Railroad, the project has posed logistical challenges. The team integrates years of experience with Metro-North Railroad, CTDOT, and the City of Norwalk to ensure safety throughout construction.

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