Water way record

A 5,100 tonne gantry crane, claimed to be the largest of its kind in the world, has been erected to help construct the Olmsted Dam on the Ohio River in the USA.

Under the Army Corps of Engineers project, the rail-mounted gantry will be used to lift and carry pre-cast concrete shells as part of the Olmsted Locks and Dam Navigation project. The gantry will be able to move the lifting frames, in which the concrete shells are placed, perpendicular to the rails.

The Army Corps of Engineers' mission is to oversee and operate the country's inland waterways system of locks and dams. Olmsted, on the Ohio River, will ultimately replace locks and dams 52 and 53, which is the USA's busiest stretch of the inland waterways system.

Washington Group/Alberici joint venture was responsible for the erection. Pre-assembly of the girders, beams, and legs took about a year. Lifting and erection of main structural members took two months to complete. Two Manitowoc 4600 crawler cranes were used to lift and place these components. The heaviest lift was a girder weighing 428,268 pounds (194 tonnes), putting both crawler cranes at 95% of their capacity.

The gantry travels on two rails each side, running the 1,200 foot (366 m) length of the pre-cast yard. They are mounted on top of a 6.5 foot (2 m) wide, 3.25 feet (1 m) deep reinforced concrete grade beam. Underneath the beam is a staggered configuration of 12 inch (300 mm) steel H-piles, totalling 2,000 units.

The gantry will support 12 strand jacks which will be the primary lifting tool for the concrete shells and capable of lifting 900 tonnes at up to 20 feet an hour (6 m/hour). It is designed so that the two strand jack beams can be hydraulically adjusted to conform to a range of lifting frame configurations.

Project facts