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Crane Hot Line

Customized Lifting System Speeds Up Rail-Bridge Rehab

Sept. 20, 2022 - Alongside Walsh Construction, Mammoet recently executed lifts for the historic Merchants Bridge rehabilitation project in St. Louis, Missouri. 

Together, Walsh and Mammoet have rebuilt the bridge by removing and replacing all three of its trusses and the east approach connecting St. Louis, Missouri, and Venice, Illinois.

Built in 1889, the rail bridge is the oldest rail structure spanning the Mississippi River.

Mammoet's solution used two large gantry systems assembled over the Mississippi River. Each new truss measured 520’ long and weighed 9,000,000 lbs. Each existing truss weighed less than half as much, 3,959,502 lbs. Each new trusses was barged into position, raised, and placed.

Mammoet’s global coverage allowed it to import the right tools for the job easily - a few large beams from its fleet were shipped to the U.S. from Singapore and the Netherlands.

The beams were then reinforced so they could resist the loads’ weight.

Each gantry was equipped with a skid system on the gantry beam so that a bridge section could be picked up from the lift location and skidded to the installation position. The only difference between the two gantry setups was the type of gantry beams, resulting in a slightly different skid setup on top.

The bridges were lifted using 5,390-USt strand jacks for the old bridge and 9,790-USt strand jacks for the new bridges.

They were connected to customer-supplied lifting lugs and lifted into place, skidded over, and either lowered onto awaiting deck barges or lifted and skidded onto the permanent bearing pads.

The beams, depending on the type, weighed 148.5-USt or 176-USt.

Walsh and Mammoet worked together for more than a month to install both systems to make the lifts of the first span. Thereafter, the gantry systems were moved over to the other piers and reassembled to allow spans two and three to be lowered and reinstalled.

The old truss bridge replacement was successfully completed with two separate gantry systems at each end of the bridge section. After the installation of the new bridge section, one of the two gantry systems was relocated to the next set of piers to remove and install the next bridge section until all three were completed.

The rehabilitation project will minimize necessary bridge maintenance in the future, restore rail service to both tracks across the bridge as well as forever changing St. Louis' 132-year-old skyline.

Mammoet has extensive knowledge and expertise relating to civil bridge projects worldwide, including the following recent project examples: Poplar Street Bridge and the Wellsburg Bridge in West Virginia to name a two.



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