en.Wedoany.com Reported - Mammoet used the lift-and-lower method to remove the entire mid-span of a truss steel bridge built in 1959 in Texas, weighing 2,300 tons, in a single operation. A new modern cable-stayed bridge has been constructed, with improved safety features in its design to better serve maritime traffic, road users, and pedestrians.
The Texas Department of Transportation (TxDOT) collaborated with FlatironDragados to demolish the old bridge and invited Mammoet to provide heavy lifting technical support. After evaluating various options such as piece-by-piece dismantling and controlled blasting, the Mammoet project team recommended the lift-and-lower method: deploying four 900-ton class steel strand jacks (two at each end of the bridge) to bear the full weight of the mid-span, then cutting the connection points and lowering the entire mid-span onto a barge. This approach reduced the number of workers required for high-altitude operations, enhancing safety; it also improved navigation efficiency as the waterway could be reopened more quickly with greater schedule certainty. The mid-span lowering was planned to take place during daylight hours for better visibility.
Mammoet Project Manager Bobby Martija explained that before the initial lift, workers made "eyebrow cuts" above the pins, leaving small openings so that the mid-span could be lifted until light was visible. This step allowed for checking bridge deflection to ensure structural stability. After confirming all clearances were correct, cutting work began. The night before the lowering operation, a barge was equipped with winches, support grillages, and SPMTs (Self-Propelled Modular Transporters). Once the barge arrived beneath the bridge, a 36-hour operational window was entered for lowering the mid-span and clearing the waterway. The mid-span was lowered nearly 50 meters using 54 steel strands. Due to the significant length of the steel strands, proper configuration of the strand jacks was critical. Initially, a simple umbrella configuration (with strands placed on the bridge deck) was used, but it was time-consuming and required personnel to manage the arrangement. The team then decided to pre-spool the steel strands: using two spooling machines (one per strand jack), which were pre-assembled at Mammoet's yard in Rosharon and then transported to the site.
After the mid-span was safely loaded onto the barge, it was transported 10 nautical miles to a nearby dock, where it was unloaded and placed onto support structures. For this purpose, two lines totaling 54 axle lines of SPMTs were used to lift the structure and move it off the deck. The underside of the mid-span was reinforced with steel before the lift. After the steel was welded to the mid-span, the SPMTs drove it and placed it onto steel supports, awaiting subsequent decommissioning and dismantling. According to HLPFI, Mammoet had previously used its Mega Jack 10000 for the first time to load and transport a 33,000-ton Floating Production Unit (FPU).
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