Spanning Urban Obstacles

by John F. Cain, Prof. Engr.; American Bridge Div., U.S. Steel, Pittsburgh, PA,

Serial Information: Civil Engineering—ASCE, 1986, Vol. 56, Issue 1, Pg. 52-55

Document Type: Feature article


Extension of Pittsburgh's Crosstown Expressway is a ¾ mile portion of a massive $500 million urban highway now under construction. The extension is a complex of five roadways on separate viaducts plus a new steel bridge over the Allegheny River. Steel girders for the viaducts were trucked to the site for placing by crane. Crossing an active railroad and its station platform was restricted to Amtrak's off peak hours. The major obstacle was a three-story warehouse where the middle third of the top story had to be removed to make way for the viaduct. Special grillage beams were placed on the roof framing to transfer all construction loads into the building columns below. The bridge is a three-span structure with steel girders that taper from 26½ ft to 17½ ft at midspan.

Subject Headings: Steel bridges | Viaducts | Urban areas | Infrastructure construction | Highways and roads | Railroad stations | Girder bridges | Steel structures

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