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New York State’s Route 9G is a state highway that branches off from and reconnects with US Highway 9 in the area of the Hudson Valley. It crosses the Roeliff Jansen Kill, a creek which drains most of the southern half of New York State’s Columbia County before flowing into the Hudson River, near the towns of Germantown and Livingston. The bridge was determined to require rehabilitation as part of the state’s Preventive Maintenance Initiative, and the works, including renewal of its expansion joint, were carried out during the summer of 2010.
A mageba sliding finger joint of type TENSA®FLEX RC was selected by the owner, the New York State Department of Transportation, for its ease of installation and replacement and due to the high maintenance cost of the alternative closed cell type joint. The limited movements of the bridge enabled a joint of size RC100 (i.e. accommodating 4 inches (100mm) of longitudinal bridge movement) to be used – the smallest version of this joint which has previously been used to facilitate movements of up to 31 inches (800mm). The finger plates of the joint are pre-tensioned downwards, ensuring constant contact of the tips of the fingers with a supporting sliding surface at the opposite side of the bridge gap. This pre-tensioning also enables the joint to accommodate small vertical movements or rotations. The joint is also quiet under traffic and comfortable to drive over. It has a modular construction and thus does not require a crane to install, with all pieces being liftable by two men. The standardized modular construction also facilitates the storage of reserve quantities for use in future projects or for rapid replacement of worn or damaged parts, and the interchanging of finger plates among lanes with most and least traffic to extend the life of the whole joint.
TENSA®FLEX RC sliding finger joint
Germantown, New York