Highway 4 Widening Project – Willow Pass Road Undercrossing, West Pittsburg, CA

The 34,000-square-foot twin structure is situated on both sides of a BART bridge structure, which was built on the Caltrans right-of-way. Interface work between the two projects was also required.

The Highway 4 Widening Project involved the widening of approximately two miles of State Route 4 from Willow Pass Road to Bailey Road with an eight-lane freeway. The project was designed to Caltrans’ latest standards with provisions for BART heavy rail extension within the median. The Project was developed in two phases. In the first phase, Beyaz & Patel studied and developed types and span arrangements for the interchange by utilizing layout, cross sections, profile, super elevation and geotechnical information, in order to arrive at an optimum solution. In the second phase, Beyaz & Patel developed the actual preparation of plans, specifications, and estimates for the interchange structure. The design included Caltrans design for multi-cell post-tensioned box girders, octagonal-shaped piers with one-way flare, and standard piling foundations.