Elevated crossing over German National Roadway no. 42

Abstract

National Road no. 42 runs along one of the shores of the river Rhine in the neighbourhood of Rhöndorf. It is crossed by a secondary road by means of an elevated crossing, which can carry light vehicles and pedestrians. The crossing is 136.5 m in length, and consists of five spans, whose lengths are 23.6, 32.1, 32.1, 28.7 and 20 m. The width of the deck is 5.5 m, of which 4 m are taken up with the road pavement, and the rest with two lateral footpaths. The structure is a boxgirder. It is a prestressed, continuous beam, which runs along a curve. Access to the bridge is along ramps built on soil embankments. Owing to the curved planform of the crossing, the torsion forces on the structure are relatively important, but the special distributions of the prestressing cables has made it possible to counteract this loading effect in a satisfactory manner. The hollow reinforced concrete supports are trapezoidal in cross-section, and have hinges at the top and 1 bottom. Thus they act as pendules. The tubes containing the prestressing cables are injected with cement after the cables have been stretched, in accordance with the technique of the contractors, Messrs. Polensky & Zöllner; a firm of worldwide reputation.