The National Railroad Construction and Maintenance Association(NRC) has awarded Walsh Construction Co. II, LLC (Walsh) with the 2022 Large Project of the Year award for its work on the Terminal Railroad Association of St. Louis’ (TRAA) Merchants’ Bridge Reconstruction project.

The complex, 45-month project replaced three existing twin-track trusses spanning the Mississippi River near St. Louis, Missouri. The original spans, constructed by George Morison and completed in 1890, were replaced with three 520-foot weathering steel twin-track truss spans weighing nine million pounds each.

Walsh constructed four, 80-foot-tall cofferdams into the riverbed to create seismically improved foundations and to encase in concrete the existing masonry pier structures. The bridge spans were replaced individually during seven-day track outages using a unique gantry lifting system that enabled the contractor to completely assemble each span on floating barges over several months then remove and replace the spans as a completed unit during the abbreviated outage period.

Walsh utilized its marine and bridge building experience to devise several innovative concepts to construct the project in the river’s swift current and 30-foot depth change. Reconstruction of the bridge required innovative project staging methods that improved the safety and speed of completion while limiting outages to rail traffic and Mississippi River traffic. New spans were constructed down river and floated into place immediately after the old spans were floated out. This allowed a rail outage on the bridge to be less than seven days and minimized the outage to the main river channel to 24 hours.

The outages required maximum coordination to close the track an driver channel, forecast weather events and river elevations, and organize labor and equipment to install the gantry, move the barges into place, and replace the spans. The project’s success came when these tasks were completed in only seven days during each outage without any safety incidents.

Another specific challenge of this project was that all of the foundation work required cofferdams, placement of concrete in confined spaces, and working through the winter months. Some other important highlights of the project include:

• Placement of 6,760 cubic yards of seal concrete underwater via tremie
• Installation of 26,000,000 pounds of structural steel in new truss spans
• Removal of 12,000,000 pounds of existing steel
• Installation of 3,500,000 pounds of rebar: 1) 1,750,000 pounds of retrofit steel on the approach spans, 2) 50,000 square feet of MSE wall•12,980 cubic yards of structural concrete, 3) 2,400 linear feet of micropile.

TRAA Chief Engineer Eric Fields, praised Walsh’s exceptional performance. “Walsh skillfully managed a complex major project that required coordination with multiple permitting agencies from two different states, municipalities, industrial river traffic, railroad traffic, pedestrian/bicycle traffic, and multiple subcontractors and subconsultants to deliver the project under budget and ahead of schedule.”

TranSystems designed the project to reconstruct the bridge and improve the adjacent approaches structures while maintaining a rail traffic schedule. The following subcontractors and suppliers contributed to the success of the project.

Subcontractors:

Collins Engineering, Inc.

D&K Welding Services

Geo-Instrumentals

Genesis Structures, Inc.

Gerstner Electric Inc.

Guarantee Electric Construction Co.

Keeley and Sons

Kelly-Hill

Luhr Bros., Inc.

Mammoet Northern USA, Inc.

Nicholson Construction Co.

Pine Waterproofing and Sealant

PJR

St. Louis Bridge

TranSystems

Suppliers

Beelman  Logistics

Doka USA

Concrete Supply  of Illinois

Infrastructure  Systems, Inc.

McDonough  Marine

Missouri  Fabricators

Silver Eagle

Skyline Steel

St. Louis Screw  and Bolt

Trinity  Products LLC

Veritas Steel  LLC