New Mississippi River Bridge Complex

The New Mississippi River Bridge project involved a group of transportation improvements that were implemented in the St. Louis, Missouri and Southwestern Illinois areas. Improvements included a new eight-lane bridge connecting Missouri and Illinois just north of downtown St. Louis, and other associated roadway improvements, including relocation of I-70 and Illinois Route 3. The construction cost for the main span of the bridge was $346 million, out of a total project cost of about $ 695 million.

DMA provided the structural engineering for the design of five bridges on the approaching roadway system, including preliminary design and cost estimating. The five bridges included:

• Structure A6419 – Two 109-foot spans, curved steel girders with cast-in-place concrete straddle bent, integral abutments
• Structure A6421 – Two 127-foot spans, curved steel girder with steel cross girder straddle bent, integral end bents
• Structure A6426 – Five span (70’, 103’, 106’, 112’, and 85’) curved steel girders with concrete intermediate bents and non-integral end bents
• Structure A6429 – Four 109-foot spans, curved steel girders with steel cross girder straddle bent, non-integral end bents
• Structure A6431 – Two 98-foot spans, curved steel girders with steel cross girder straddle bent, integral end bents

DMA also provided surveying services in the form of property and topographic surveys for the project. We performed utility and right-of-way surveys for the study of three alternate routes during the early design stages. We also provided detailed topographic, utility, and property surveys including legal descriptions and exhibits for over 100 affected parcels.

*image courtesy of MoDOT