By Brian Johnson
Dolan Media Newswires
The $626 million St. Croix Crossing project hit a key milestone late last week, as construction workers installed the fifth and final crossbeam for the mile-long bridge over the St. Croix River that connects Wisconsin and Minnesota.
Crossbeams for the bridge under construction between Minnesota and Wisconsin connect the pier columns at each river pier location, according to the Minnesota Department of Transportation.
Crossbeam construction started in spring 2014 at Pier 8, which is closest to the Minnesota shore.
Crews are “post-tensioning” the final crossbeam at Pier 11, which means they’re essentially pulling cables tight “like a rubber band” through the structure, said Kristin Calliguri, MnDOT’s St. Croix Crossing spokeswoman.
As soon as the end of the month, workers will begin to lift concrete segments into place for Pier 12, which is closest to the Wisconsin side, Calliguri said. The segments form the foundation for the driving surface.
The segments over the river are 48 feet wide and 18 feet tall, and they weigh 170 tons on average. They are being formed at a casting yard on Grey Cloud Island and shipped by river barge to the construction site.
The main river span will include about 650 segments, which are hoisted into place with help from a “segment lifter” imported from Europe.
Meanwhile, workers are installing the second set of stay cables at Piers 8 and 9, and pile-driving will continue through the end of the month for the foundation of Pier 13 on the Wisconsin bluff.
Not everything has gone according to plan.
MnDOT said in early September that “project complexities” had forced it to delay the opening of the new bridge. The bridge was expected to open to traffic in fall 2016, but MnDOT now says that work will “continue into 2017.”
Calliguri said Friday that the project team is “still working through” the schedule and potential cost impacts related to the delay. A more precise schedule should be known by the end of the year, she said.
A joint venture of Black River Falls, Wis.-based Lunda Construction and Burnsville, Minn.-based Ames Construction is building the bridge’s superstructure.
The bridge design work was led by HDR, an architectural and engineering firm based in Omaha, and North Vancouver, B.C.-based Buckland & Taylor.