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Bay Bridge/Yerba Buena Island Ramp Safety Improvements PSR San Francisco, CA

As part of the rebuild of the Bay Bridge East Span, the City and County of San Francisco proposed modifications to the ramps to and from the East Span in order to allow improved access to and from Yerba Buena Island. The current geometric design of the ramps, the on-ramp merge lengths, and off-ramp deceleration lengths for the six ramps do not meet Caltrans standards. The purpose of the project is to:

  • Upgrade ramps to current geometric and seismic standards to the extent physically and economically feasible.


  • Improve traffic operations to and from the San Francisco-Oakland Bay Bridge and improve driver safety and comfort.


  • Increase deceleration and acceleration lengths for westbound on and off ramps.


  • Connect the new westbound ramps to the San Francisco-Oakland Bay Bridge Transition Structure.

CHS Consulting Group was responsible for traffic operations analysis for the Project Study Report (PSR), Project Report (PR), and Environmental Impact Report (EIR). CHS prepared a traffic forecast report and a traffic operations report. For the traffic forecast report, CHS developed future-year (2030) traffic volumes for the Bay Bridge and six associated ramps to and from Treasure Island and Yerba Buena Island. For the traffic operations analysis, CHS performed freeway mainline and merge and diverge analysis, and ramp junction levels of service analysis with and without ramp metering.

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