Published May 6, 2016
In Roads and Bridges


MLC300 a Perfect Balance
When completed in 2017, the St. Croix Crossing Bridge will be only the fourth extradosed bridge in the country. Coming from the French word “extradossé,” meaning “the exterior curve of an arch,” these attractive bridges are increasingly popular internationally. An extradosed bridge is a hybrid of concrete box girder and cable-stay designs that minimizes the height of the towers from which cables support the bridge deck. The visually appealing design increases aesthetics while also helping to reduce construction costs. The new four-lane structure will replace the old Stillwater vertical lift bridge that connected the cities of Oak Park Heights (MN) and St. Joseph (WI). The new structure is intended to provide a safer, more reliable river crossing while helping to relieve traffic congestion in the St. Croix Valley area.

The project is a complex, massive, multiyear project estimated to cost several hundred million dollars. It is such a big project that there are scheduled paddleboat tours for the public that include the construction site in their excursions (weather permitting).

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—forming the driving surface of the bridge. Most of the segments are 180-tons, each 48 feet wide, 18 feet tall, and 10 feet deep, and 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 in search of a Manitowoc 2250 to handle the lifting and setting of the huge segments. The two companies have a good, longstanding working relationship. Lunda knew that Dawes, as a member of the ALL Family of Companies, would have the right equipment for the project. In fact, ALL has the largest fleet of privately-owned crawler cranes in North America.

Adding to that fleet, ALL purchased 10 new 330-USt Manitowoc MLC300 crawlers last year, 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.

One of the reasons customers choose ALL is their ability to select the best equipment for every job. Dawes’ sales representative Joe Ruddell suggested to Lunda that the MLC300 would actually be the ideal machine 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. We knew if we used the MLC300, 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 feet of main boom and 190 tons of counterweight, began working onsite in July 2015. On the river, once set, the pre-cast segments are connected to both ends of a pier table, a flat surface atop each pier (there are five piers total in the river portion of the bridge). Subsequent segments are then installed in both directions, moving outwards from the pier to form the 600-foot spans between each pier location. The segments are joined together with epoxy, after which, steel strands are fed through the segment’s hollow plastic ducts. Those are then pulled tight using a hydraulic jack to anchor the segment into place. All the stressed strands are interconnected, and connect back to each pier, making for a strong bridge structure.

Work is expected to continue through this summer. With the new MLC300 on the job, Dawes was able to deliver both the powerful lifting capacity and stability that Lunda needed—as well as offering cost savings on both the time and prep needed to put the crane to work. That’s the ALL way: providing customers the right balance of the most efficient equipment with every available advantage.

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This article was originally published in ALL's Lift Line magazine, Spring/Summer 2016.