Assessment of heavy-lift equipment for in-the-wet construction of navigation structures

Abstract : In recent years, the U.S. Army Corps of Engineers has launched major developments in underwater construction of locks and dams, using the so-called "in-the-wet" or "offsite prefabrication" construction method. This innovative method uses precast concrete modules as the in situ form into which tremie concrete or other infill material is placed directly without use of a cofferdam. The tremie concrete is designed to work in composite action with the precast concrete modules. Numerous in-depth investigations have been conducted by several Corps districts and their consultants to evaluate the feasibility of the in-the-wet method at various potential sites of U.S. inland waterways. These studies have shown that the innovative construction method can provide substantial benefits in cost, construction time, risk reduction, and facility utilization, while minimizing disruption to river traffic and reducing environmental impact.