Geosynthetic Reinforced Soil Integrated Abutments at the Bowman Road Bridge in Defiance County, Ohio

This paper will discuss the design, construction, and performance of a geosynthetic—reinforced soil (GRS) integrated abutment used for Bowman Road Bridge, built in Defiance County, Ohio, during the fall of 2005. The project was part of the Federal Highway Administration's (FHWA) "Bridge of the Future Program" to develop technologies to build more efficient, durable 70 to 90 foot single-span bridges. One of the most significant aspects of this project was the evaluation of the "integrated abutment" concept; this simple method of combining the substructure with the superstructure is different from the "integral abutment" method of construction. The bridge consists of prestressed concrete box beams supported on GRS abutments without the use of a deep foundation to support the superstructure. The GRS abutments were built on a Reinforced Soil Foundation (RSF) over the clay subsoil. The bridge has no cast-in-place concrete. The bridge also does not have an approach slab; the intent was to allow the bridge and the adjacent road to settle together, providing a bump free, smooth ride for drivers traveling over the bridge. The cost to construct this bridge was about 20 percent less than the quoted price of a bridge supported on pile-capped abutments with 2:1 slopes. The bridge was instrumented and surveyed to evaluate performance and to refine the "integrated abutment" design concept. To date, the performance of the bridge is excellent and the angular distortion of the superstructure is well within AASHTO criteria for simple supported bridges.