Robert McAfee Bridge

Information and Findings From Pennsylvania's Historic Bridge Inventory

Discussion of Bridge

The 8-span, 642'-long bridge has a 380'-long, 1-hinge, steel deck arch main span with two, built-up arch ribs, and Pratt trussing to carry the deck. Built in 1928, the bridge was originally flanked by stone arch approach spans but these were replaced by steel stringer spans in 1981. As part of the project to widen the bridge, a cantilevered deck section with safety-shape concrete parapets was placed on the steel arch. Although the bridge has lost its approach spans and original railing treatment, the 1-hinge steel arch span is complete and still functioning as originally designed. The 1-hinge design is very uncommon and makes the arch statically determinate, an advantage for calculating stresses and proportioning members to achieve an economical design. In the United States, a very limited number of 1-hinge steel arch bridges were built between 1920 and 1940. This 1928 example dates from Pittsburgh's golden age of bridge building when city and county engineers used a variety of long-span bridge types, and demonstrated a willingness to apply some very unusual designs, to improve major ravine and river crossings. The bridge is historically and technologically significant.

Discussion of Surrounding Area

The bridge carries a 2 lane street with sidewalks over a ravine and two city streets. The area is a mix of late-19th to late-20th-century residential, commercial, and light industrial development. The setting does not have the cohesiveness or integrity of a potential historic district.

Bridge Considered Historic By Survey: Yes