Rail Trench Structure Design at Port of Vancouver USA

Located at the Port of Vancouver USA, the West Vancouver Freight Access Schedule 2 Rail Project 16 will connect the BNSF north/south mainline track with the Port rail system. The current rail entrance blocks the mainline when unit trains enter or leave the Port. This resulted in the need to develop a new entrance, the only feasible alignment being along the north bank of the Columbia River and beneath the existing BNSF Bridge 9.6. A 1,350-foot (411.5 meters) portion of this track will be carried by a partially elevated reinforced concrete structure that will protect the rail from 100-year flood waters and support it along the irregular river bank. This paper describes the constraints that dictated the design features and the resulting configuration of the partially elevated reinforced concrete structure. To resist flooding and provide the required clearance under the existing rail bridge, a watertight, continuous concrete trench was selected as the preferred solution. Closely spaced batter piles support 1,100 feet (335.3 meters) of the trench and provide lateral resistance to seismic loads and buoyancy resistance. Portions of the rail trench structure will be constructed below the U.S. Army Corps of Engineers' ordinary high water mark of the river and will be subjected to in-water work timing restrictions. The river is home to several species listed under the Endangered Species Act, and the Port has undertaken a very low-impact approach to construction of the rail trench: no work will be conducted in the flowing water of the river. This necessitates careful planning and sequencing of the work, taking into account projected river levels and tidal fluctuations. Other challenges include an extremely constricted site with limited access and the need to minimize impacts on adjacent tenants and their operations. When constructed, the rail trench structure will provide a unique facility designed to meet the latest structural, seismic, and environmental requirements and maximize operational efficiency for the Port.