I-90 Mississippi River Bridge Approaches and US 61/14 Interchange

SRF led the complete reconstruction of the roadway approaches to I-90 (which spans the Mississippi River), three miles of retaining walls, and seven inland bridges (four of which are complex steel curved bridges) as part of the overall interchange design. The team for this highly complex project provided final plans on an aggressive schedule for $100 million of infrastructure improvements.

SRF coordinated with the Minnesota and Wisconsin DOTs and several federal agencies, including the US Fish & Wildlife Service, prepared complex construction staging and maintenance of traffic plans, and met strict drainage parameters due to the proximity of the Mississippi River. The project included coordinating with the I-90 river bridge structure designs (performed by another consultant) and incorporating Wisconsin approach roadways, which were realigned due to the shifting of the new river bridges.

Visual Quality. SRF also led a visual quality effort to incorporate aesthetic value to the river bridges and interchanges and conducted regular project management meetings and design reviews to assist in acquiring design approvals in an expeditious manner. In addition, SRF developed a Design Quality Management Plan and Project Manual to keep the team coordinated and promote high quality designs.

Water Resources. The drainage design presented a number of challenges. The steep topography and narrow roadway corridor required deep excavations to construct many drainage pipes and culverts. Therefore, existing culverts were inspected to identify those that could be rehabilitated. The resulting design included both new and lined pipes with up to 50 feet of cover and pipe jacking of up to 54-inch diameter pipes to cross the existing railroad corridor. SRF designed nearly 25,000 lineal feet of storm sewer and culverts. Our design also included bridge deck drainage analysis energy dissipation measures, and 2,000 feet of steel casing for pipes near retaining walls.

ITS. SRF provided a comprehensive ITS deployment. To enhance incident management at the interchange, SRF designed four CCTV installations that provide views of all roadways approaching the bridges along with two Dynamic Message Signs (DMS) for traveler information. To assist with weight enforcement, a weight-in-motion system was also designed for vehicles entering Minnesota. An anti-icing system was also designed to improve safety on all bridge spans. Due to the remote location of the project, creating a robust data connection was challenging. SRF developed a solution for a wide-area connection using planned and existing Wisconsin fiber optic infrastructure to allow for high-capacity, low-cost data transport that allows both states access to the ITS assets.