CSAH 1 Bridge over the Mississippi River

The City of Sauk Rapids, in conjunction with Stearns and Benton Counties, City of Saint Cloud, LeSauk Township, Saint Cloud APO, MnDOT, and BNSF Railway, identified the need to construct a new CSAH 1 bridge over the Mississippi River to replace the existing two-lane bridge constructed in 1948. Initially, SRF prepared a bridge type study report to determine the most feasible type and spans for the location. After the study was completed, SRF prepared preliminary and final plans for the river bridge and a pedestrian helix ramp to a local park. This complex project required coordination with multiple agencies for the approval process. Additionally, site conditions made plan preparation and construction difficult:

• The bridge crosses the river at a rapids location with fast-moving water, which required special caisson designs.
• The DNR requirements for temporary access roads to construct the piers were very restrictive and required special hydraulic modeling for construction phasing.
• The steel spans over the river consisted of 224 feet, 295 feet, 265 feet, and 220 feet. The tight vertical clearances over the railroad required a cast-in-place flat slab with minimum shoring allowances.

The complex pedestrian helix design was 35 feet high. The project also included reconstructing and realigning approximately 1,300 feet of Benton Drive South from 1st Street South to 4th Street North as a four-lane divided roadway.

In addition to our design work, SRF assisted in obtaining the railroad agreement with BNSF Railway.