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Merchants Bridge West Approach Replacement

The Merchants Bridge is double-track railroad structure that crosses the Mississippi River just north of downtown St. Louis. It has been in service since 1890. The three main river spans consist of 518’ Pennsylvania through trusses supported on masonry piers. Deck trusses that flank the main spans were replaced with deck girder spans in 2005, and the remainder of the approach structure consisted of steel built-up girders supported atop steel towers and bents.

Modjeski and Masters initially performed the design of a traditional structure for the replacement of the west approach. However, in 2015, the Terminal Railroad Association of St. Louis (TRRA) determined that the most cost-efficient way to replace the aging west approach spans was to construct a retained fill structure around the existing spans. The TRRA chose to repackage the design and use the Design-Build model of project delivery, selecting M&M to represent and assist the TRRA throughout the project.

During the procurement phase, M&M assisted the TRRA by developing the RFQ and RFP documents. M&M also assisted with the evaluation of the Design-Build teams and their proposed concepts. Through the duration of the project, M&M assisted the TRRA by reviewing design submittals, performing daily site visits, and attending regular progress and design meetings. During construction, M&M also worked closely with the Missouri Department of Transportation (MoDOT) LPA railroad liaison to ensure that all the appropriate Federal Railroad Administration (FRA) documentation was completed.

Bridge Geometry