Redesign of the Broadway Avenue Bridge over the Boise River

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Sondra Miller


GSD Engineering was tasked with developing a design for reconstructing The Broadway Avenue Bridge, located in Boise, Idaho. The current bridge was constructed in 1956 and crosses the Boise River on US 20/26 (Broadway Avenue) adjacent to the Boise State University campus. The National Bridge Inventory Database assigned the bridge a rating of 48.4 out of 100, less than the standard of 50, indicating the need for its replacement. The existing bridge has four lanes that are not adequate to meet current and projected future vehicle capacity issues, narrow sidewalks, and no bicycle lanes. The replacement bridge design will increase vehicle capacity and improve driving, biking, and walking safety.

The replacement bridge design will consist of three simple spans with two pier supports to be constructed in the Boise River. The bridge deck design will have six 12-foot travel lanes, two 8-foot sidewalks, two 6-foot bike lanes, and be constructed of reinforced concrete, supported by steel girders, meeting all current AASHTO and ITD design standards. The bridge will also be raised 1.2 feet to account for realignment of the Boise River Greenbelt under each end. Broadway Avenue approaches will be redesigned to meet the new bridge elevation. Construction activities will shut down traffic utilizing the Broadway Avenue Bridge, necessitating development of a traffic mitigation plan to smoothly reroute traffic flows during construction.

This document is currently not available here.