St. Croix Crossing Links Wisconsin and Minnesota

ST. CROIX Crossing - a four-lane highway bridge spanning the St. Croix River to link Minnesota and Wisconsin - has recently opened to traffic. Construction of the project, which started in 2014 and ended last summer, can be seen in this new video from EarthCam. 

Above: The St. Croix Crossing under construction (image courtesy of HDR).

Commissioned jointly by the Minnesota and Wisconsin departments of transportation, the St. Croix Crossing dramatically improves connectivity between the Minneapolis-St. Paul area and the state of Wisconsin.

Above: The bridge is a new connection between Minneapolis-St. Paul metropolitan region in Minnesota and the state of Wisconsin ( image courtesy of HDR).

The USD $647 million crossing replaces the aging, two-lane Stillwater Lift Bridge, which opened to traffic in 1931.

Known to experience high levels of traffic - some 18,000 vehicles a day - that crossing was deemed to be ‘structurally deficient ’ following an inspection in 2008.

Above: The Stillwater Lift Bridge opened to traffic in 1931 (image courtesy of Wikimedia).

Designed and engineered by infrastructure specialist HDR, the St. Croix Crossing’s unusual extradosed structure combines principles of cable-stayed and prestressed box girder bridges.

The aim is to achieve a lower profile with fewer piers. This was deemed necessary as the crossing traverses the Saint Croix National Scenic Riverway.

Above: The unusual design of the St. Croix Crossing is due to the designation of the river as a National Scenic Riverway (image courtesy of HDR).

The mile-long bridge is composed of 988 pre-cast segments and features 5 slender piers in the river. All in all, the St. Croix crossing contains 140,000 cubic yards of concrete and 19,000 tonnes of steel.

Above: Pre-cast segments were used for the main roadway, but the approach was partially built with in-situ concrete (image courtesy of HDR).

Initially, the timeline for project was much longer. Construction on a replacement bridge was supposed to start in 2024, but Minnesota passed legislation in 2008, requiring the renovation, replacement or upgrades of any potentially dangerous bridges by 2018.

Above: St. Croix Crossing had to be built much earlier than initially planned due to state legislation requiring substantial infrastructure upgrades in Minnesota (image courtesy of HDR).

However, the design did not convince some who opposed the bridge on environmental and scenic grounds.

The situation escalated to the United States Congress, which eventually approved the construction of the project. A bill was signed into effect by President Obama in 2012, finally clearing the path to construction.

Above: Due to its protected location, the construction of the St. Croix Crossing had to be approved by the US Congress and President Obama (image courtesy of Wikimedia).

The Stillwater Lift Bridge closed to traffic as the new crossing opened. The structure is listed on the National Register of Historic Places and is currently being converted into a pedestrian and cycling bridge, escaping demolition.