SR 4 East Corridor, Contra Costa County
The Project
The SR 4 East Corridor is the sole East-West corridor in Contra Costa County and is one of four corridors linking the urban Bay Area with the Central Valley. This corridor has been the focus of the Contra Costa Transportation Authority (CCTA) for over 15 years. The project consists of widening SR 4 from a four lane facility with a narrow median to an eight lane facility with a median accommodating transit (BART or e-BART) from Bailey Road east to the SR 4 Bypass, a distance of ten miles, encompassing six interchanges from preliminary engineering (Project Study Report) through construction.
MTCo provided preliminary engineering including a Major Investment Study and a Project Study Report for the easterly six mile section, environmental clearance, final design and right of way surveys for the 1.5 mile Railroad Avenue to Loveridge Road section including the Railroad Avenue interchange, final design and right of way surveys for the one mile long Somersville Road interchange, environmental clearance and final design for an interchange modification at Hillcrest Avenue and construction staking for the one mile long Bailey Road to Railroad Avenue project.
The Challenges
The focus of the CCTA has been on Project Delivery and on developing true working partnerships with Caltrans. The CCTA wanted to shave a year off of the programmed start of construction for the Railroad Avenue project to “keep the momentum going” in the corridor. On the Somersville Road project CCTA and Caltrans agreed that Caltrans would take a lead role in specific design elements, while at the same time helping to familiarize the local agencies on Caltrans policies and procedures.
There has been continual development and planning for the SR 4 east corridor that can significantly impact design direction. So it has been challenging to maintain adequate flexibility in design approach to accommodate design development of future transit facilities (at Railroad Avenue to accommodate a future BART station and end of line track-switching alignment; at Somersville Road to shift from no transit in the median to accommodating transit during the middle of the design process).
The Results
MTCo worked with the CCTA to develop a construction sequencing plan for the Railroad Avenue interchange that divided the work into three construction packages (one local agency project, one encroachment permit project and the mainline Caltrans-administered project). This approach allowed the overall construction project to be completed 1 to 1.5 years ahead of schedule.
Similarly MTCo worked with CCTA to develop a design program that has expedited the Somersville Road interchange, even while completely changing the alignment to accommodate a future transit extension. Further, MTCo and Caltrans did develop an integrated design team with Caltrans providing the complete design and specification development for the drainage component.