Hollister Avenue
Underpass

The proposed replacement of the Hollister Avenue Underpass is part of the larger Hollister Avenue/State Street improvements project between San Antonio Road and State Route 154 which will widen Hollister Avenue from two lanes to four lanes.  As part of the County of Santa Barbara's improvement project, Cornerstone prepared an engineering feasibility study for the replacement of the existing UPRR underpass.  The existing underpass is seismically deficient and also has substandard vertical clearance.  The project was highly constrained because of the limited room between UPRR's right-of-way and Highway 101, the adjacent intersection at Modoc Road, and the significant right-of-way cost impacts. This required innovative solutions to minimize impact and costs while maintaining traffic along Hollister Avenue during construction.  Working with the County, Cornerstone developed bridge replacement alternatives, construction staging concepts, and developed a preliminary temporary shoofly for the project.   Because of the existing vertical clearance and current UPRR clearance requirements, the project will require the railroad tracks to be raised or the roadway to be lowered by approximately 3 ft.  Cornerstone also led the coordination effort with UPRR and Caltrans where they had to consider impacts to the railroad operations, constructability, traffic handling and staging, impacts to adjacent commercial and residential properties and Highway 101, and roadway drainage.   The project included an Accelerated Bridge Construction (ABC) including staged construction of the substructure and a build and slide of the bridge steel through girder from the temporary shoofly to the mainline to allow traffic to be maintained below the existing bridge during construction.