Precast Counterfort Seawall Simplifies Road Widening Project In Usvi

The U.S. Virgin Islands (USVI) Department of Transportation is executing a multiphase Federal Highway Administration (FHWA)-funded reconstruction of Veterans Drive in the city of Charlotte Amalie, St. Thomas. The first phase involves widening and reconstruction of about 2,500 linear feet (760 meters) of roadway and includes provisions for a people-friendly sidewalk along the waterfront. The seawall will retain fill soils varying in height from 8 to 14 feet (2.4 to 4.3 meters). The bid documents called for a stacked modular block system for the seawall, which would have required significant underwater work. The design-build team adopted a system of modular full-height precast concrete counterfort units placed over prepared seabed and connected together by a cast-in-place concrete beam. Precast concrete coping units placed over the wall provided a pleasing finish. Grade 60 stainless steel rebars provided a 50-year design life. All precast elements were fabricated in Virginia and barged to the island. The modular concept allowed the contractor to achieve good placement control for the mostly curved alignment (with three outlooks) and met the stringent architectural finish required.