St. Croix Crossing

The Stillwater Lift Bridge had been a point of frustration for Minnesota and Wisconsin commuters long before it was deemed fracture-critical in 2008. More than 18,000 vehicles traveled the 85-year-old bridge daily, and traffic often backed up for miles. Because the bridge crossed the St. Croix National Scenic Riverway, it would take federal legislation granting an exemption to the Wild and Scenic Rivers Act before construction of a new bridge could begin in 2013.

Ames served as a joint venture partner for the construction of the mile-long St. Croix River Crossing and the Minnesota approach to the bridge. The location of the new bridge is a mile downstream from the Stillwater Lift Bridge, easing traffic congestion by bypassing the city of Stillwater.

The bridge features an extradosed design combining a cable-stayed build with a cast segmental concrete box design. The innovative design was selected to minimize environmental impacts by using fewer piers in the water. In addition, the shorter cable-stayed towers are below the bluff’s line of sight.

The complex construction required methodical completion of each step to build the project successfully. Construction started with the approaches and bridge foundations, followed by erecting the bridge deck and connecting the cable stays.

The bridge is located next to a historic area, and the riverway is inhabited by threatened and endangered species. At every turn, environmental considerations were at the forefront, with MnDOT and WisDOT executing the most extensive mitigation package in their histories.

On August 2, 2017, the St. Croix Crossing opened to the public. Strikingly beautiful, the structure is only the second extradosed bridge to be built in the U.S. With a walking path that includes several overlooks, this new Minnesota landmark has become a destination for crossing the scenic St. Croix River on foot.