A perfect balance

Feb. 10, 2016

Once it’s completed in 2017, the new St. Croix River Crossing bridge will be the fourth extradosed bridge in the country. Increasingly popular internationally, an extradosed prestressed bridge is a hybrid of concrete box girder and cable-stay design that minimizes the height of the towers from which cables support the bridge deck. The design increases aesthetics and also helps reduce construction costs. The new four-lane structure will replace the old Stillwater vertical lift bridge that connected cities in Minnesota and Wisconsin.

Constructing the St. Croix River Crossing is a complex, massive, multiyear project estimated to cost several hundred million dollars. Foundation work began in 2013. By 2015, contractor Lunda Construction was in search of a crawler crane to handle the lifting of precast concrete bridge deck segments. The 180-ton segments, each 48 ft wide, 18 ft tall, and 10 ft deep, would be brought from the casting yard on a barge, down the Mississippi River and up the St. Croix River to the construction area. Lunda called Dawes Rigging & Crane Rental, a member of the ALL Family of Companies, originally seeking a Manitowoc 2250 to handle lifting and setting the huge segments. The two companies have a longtime working relationship, and Lunda knew that Dawes would have the right equipment for the project.

However, ALL had recently purchased 10 new 330-USt Manitowoc MLC300 crawler cranes, a revolutionary crane introduced in 2014. These machines are designed with the cutting-edge VPC system, a variable position counterweight that shifts the counterweight on a rail system when the boom moves, balancing the crane’s center of gravity automatically. VPC eliminates the needs for carbody counterweights and reduces the crane’s overall operating footprint, cutting the number of mats by up to half of what would normally be needed—thus also reducing ground preparations.

Dawes’ sales representative Joe Ruddell suggested that the MLC300 would be ideal for the St. Croix River Crossing. “I wanted to get them the best crane for the job. Because of the VPC system, the machine is relatively easy to move, especially on unstable ground or ground that isn’t completely flat. The counterweight balances it. It also doesn’t take up as much real estate as the 2250. If we used the MLC300, we knew our customer wouldn’t need to bring in mats or build a platform or foundation, which helps cut down greatly on costs and time.”

The MLC300, configured with 157 ft of main boom and 190 tons of counterweight, began working onsite in July 2015. Work is expected to continue through summer 2016.

With the new MLC300, Dawes was able to deliver both the powerful lifting capacity and stability that Lunda needed for the job—plus cost savings on both the time and prep needed put the crane to work. 

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