INCREMENTAL BRIDGE CONSTRUCTION COSTS FOR HIGHWAY COST ALLOCATION

The procedures and results of an incremental load analysis of bridge construction costs that consisted of the design and pricing of 960 bridges were documented. These 960 bridge type, load, and span combinations were composed of 11 different bridge types ranging in span from 9 to 72 m (30 to 240 ft) and designed for loads ranging from H2.5 to HS25. The bridge type and span combinations included in this factorial reflect current national design and construction practices, as revealed by statistical summaries obtained from the National Bridge Inventory data base. The incremental bridge cost results are important inputs for the highway bridge cost allocation procedures carried out at the federal and state levels. In addition to the bridge cost results, moment ratios of live load to dead load were recorded during this bridge design exercise. The moment ratios obtained in such an exercise can contribute significantly to policy evaluations--especially those that attempt to define the economic impacts of vehicle size and weight changes on bridges at the highway network level.