Mammoet tackles Texas transport

Aiding construction on the “Signature Bridge” project in Irving, Texas, USA, Mammoet set four precast box-girder bridge units into place.

The international heavy lift and transport specialist was working for the Texas Department of Transportation and its general contractor Webber, LLC. The new bridge will stretch 500 feet (150 metres) over State Highway 114 and will connect the former Texas Stadium site to a new mixed-use development, which will include a new Dallas Area Rapid Transit light rail station.

The original plan was to use jacking and skidding equipment so the bridge could be built on top of the existing one and skidded over to its new foundation. When reviewing the engineering, Mammoet devised a solution for the units to be built directly on the ground in an off-site location, after which each one would be picked up and self-loaded using SPMT. This method is known as accelerated bridge construction or ABC.

ABC avoided the need for work to be done at height, thereby eliminating many safety concerns, and allowing for quicker loading time than originally anticipated. It shortened the job by two overnight shifts.

To execute as planned, a trench was dug underneath each 120 foot (37 metre) section to allow installation of a beam under each end of the bridge unit. The sections were then lifted using a 700 ton (635 tonne) capacity gantry system and once elevated, Mammoet drove SPMT underneath to load each piece before delivering to the abutments.

The route from construction site to final setting presented challenges, including steep grades and tight spaces to negotiate. By co-ordinating with Webber and careful engineering, the team set all four bridge units in the allotted traffic outage. Since the start of the project in 2017, there were more than 170,000 hours with zero recordable incidents.