WisDOT Grantosa Drive Bridge Rehabilitation

The project included two bridges on West Grantosa Drive spanning WIS 145. Constructed in 1965, these 4-span steel girder bridges were in need of rehabilitation to maintain the existing facility life. This project also included designs for thin polymer overlays and load ratings on 8 bridges. These included STH 145 northbound and southbound over 91st Street, Little Menomonee River Parkway, and Mill Road, plus STH 175 over Silver Spring Drive and STH 181 over Silver Spring Drive.

The scope included both preliminary and final design for the bridge rehabilitations and adjacent approaches and all necessary reports and documentation to complete the PS&E submittal. The scope of the West Grantosa Drive structure rehabilitation included the replacement of the existing bridge decks and calculating new load ratings. Other structure rehabilitation items included blasting and repainting the existing steel girders and concrete repair.

A unique structural aspect of this project was revealed during field inspections to establish the rehabilitation scope. Abutment expansion bearings were found to be excessively out of alignment. Further investigation suggested that the abutments, founded on shallow footings, had slid and/or rotated towards the roadway below. Collaboration with WisDOT BOS and SE Region Bridge Maintenance staff generated several alternative retrofits, ultimately opting for the conversion of the abutments from expansion to a semi-expansion style. With the removal of the existing hold-down bearings, thickened deck ends over the abutments will provide additional dead load to resist girder uplift.

The bridges on Grantosa Drive were rehabilitated one structure at a time to minimize impacts on the traveling public and the City of Milwaukee. While the eastbound structure was closed, detours were provided while traffic on the westbound structure was maintained. The opposite occurred when the westbound structure was rehabilitated. Multiple staging alternatives were
considered on WIS 145 for the rehabilitation of the Grantosa Drive structures. These included single-lane closures, double-lane closures, and the full closure of STH 145. The final alternate selected balanced the impacts on the traveling public while maximizing the size of the work zone to reduce construction costs.

Bicycle accommodations were an important consideration on Grantosa Drive. Bicycle lanes were provided west of the bridges over WIS 145 and were proposed by the City of Milwaukee east of WIS 145. Previously, a short segment between W. Fond du Lac Avenue and West Villard Avenue provided three lanes of traffic in each direction and no bicycle accommodations. Analysis of the traffic on Grantosa Drive showed only two lanes of traffic in each direction would accommodate the traffic on the roadway. The structures were configured to provide full bicycle lanes across the rehabilitated structures.