Lessons learned from the Tappan Zee Bridge, New York

mmpPDFResearch PaperBridge decksBridge management systemsRehabilitation (Maintenance)CaliforniaCalifornia. Dept. of TransportationRao, ChetanaTajirian, ArmenStubstad, RichardNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresUS Transportation CollectionThe Governor Malcolm E. Wilson Tappan Zee Bridge carries the New York Thruway's mainline across the Hudson River. The bridge showed signs of deterioration from the early 1990s. Damage due to increased traffic levels, chloride ion penetration in the concrete deck, and other environmental factors indicated that the bridge deck had outlived its design capacity and was in need of rehabilitation or replacement. Given the critical location and traffic volume on the Tappan Zee Bridge, conventional rehabilitation alternatives pose logistical problems for traffic detour. Between 1996 and 1998, the New York State Thruway Authority (NYSTA) replaced the entire deck of the 13 east deck truss spans and along the median of the west trestle spans between Piers 1 and 81. Two different types of precast deck units were used in these operations, Inverset and Exodermic. The Inverset and Exodermic systems are two precast deck units that can be used for rapid reconstruction or repair of bridge decks without disrupting traffic. The Inverset is a composite concrete deck on steel girders, while the Exodermic is a composite deck on a steel grid. The installation procedure of the deck is discussed in as much detail as required in this report to acquire a broad idea of the extent of the project. Several other details are, in most cases, very specific to this project and designed for this application. The choice of a precast deck type is case-specific. However, the lessons learned from the successful execution of this project are of great value to agencies that might consider similar projects. References, 27 figures, 1 table, 32 p