Project Location: Stillwater, Minnesota
Client: MnDOT & WisDOT
Synopsis of work:
When the Stillwater Lift Bridge was deemed fracture-critical in 2008, interstate commuters began to envision relief from the increasing frustration associated with crossing the 85-year-old iconic structure; more than 18,000 vehicles traveled the bridge daily and traffic often backed up for miles. It would take decades of debate, an act of Congress and a bill signed by the president before construction on a new bridge would begin in 2013.
Located a mile downstream from the Stillwater Lift Bridge, the site selected for the new St. Croix River Crossing would minimize potential negative impacts on the surrounding area's historic and natural resources, and bypass the city to eliminate traffic congestion. The bridge is a hybrid design structure combining a cable-stayed build with a cast segmental concrete box design. The overall project connects Minnesota and Wisconsin over the St. Croix River and includes new approach highways, historic and cultural preservations and environmental protections for the river. Ames was a joint venture partner for construction of the Minnesota approach and the mile-long bridge structure.
The bridge is located in a national scenic riverway, next to a historic area, and in an area 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 respective histories to offset potential impacts.
The innovative and proven design was selected to minimize environmental impacts by using fewer piers in the water, and its shorter cable stay towers remain 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.
On August 2, 2017, the new St. Croix Crossing opened to the public. Strikingly beautiful, the structure is only the second extradosed bridge to be built in the U.S. This new Minnesota landmark has become a destination spot for many wanting to cross the scenic St. Croix River by foot, with a walking path that includes several overlooks.
The original Stillwater Lift Bridge will be converted for exclusive use by bikers and walkers, giving new life to the iconic bridge and becoming part of the loop trail connecting the two bridges.
Click to enlarge any of the photos below: