VTA outlines $198 million plan to add San Antonio southbound ramp, bike-and-ped facilities on US 101

The Santa Clara Valley Transportation Authority (VTA) told the Mountain View Council Transportation Committee that the US 101 San Antonio and Ringstorff interchange improvements are in the environmental phase and would add a new southbound on‑ramp at San Antonio, remove the Charleston on‑ramp at Ringstorff, add a southbound auxiliary lane and new bicycle and pedestrian facilities.

The project “is about $198,000,000,” VTA senior transportation engineer Shanti Chitraddi said during the committee’s April update, and VTA has funding only for the project initiation and environmental phases so far. “For the environmental phase, we have received a total including match of about $8,000,000,” Chitraddi said; she said the PID and environmental phase together total roughly $10 million and that the local match for early work included funds from Google and Measure B. VTA staff said design and construction phases do not yet have secured funding.

VTA and city staff said the work responds to deficiencies Caltrans identified after the 101 northbound auxiliary lane project: closely spaced interchanges that produce short weaving distances, a short southbound on‑ramp at Charleston that creates a weaving conflict at Ringstorff, and an incomplete San Antonio interchange with no southbound on‑ramp. The proposed fix, as described by Chitraddi, is to add the San Antonio southbound on‑ramp, remove the Charleston on‑ramp to reduce weaving at Ringstorff, add an aux lane between the two interchanges, widen ramps to increase storage, and replace existing bridges with higher‑clearance structures.

The plan includes bicycle and pedestrian improvements described as “complete streets” features: class 1 grade‑separated multi‑use paths along segments of Ringstorff, new sidewalks where missing, squared and widened ramps to reduce conflicts with walking and cycling, and carpool lane additions where feasible. Chitraddi described a proposed bi‑directional, grade‑separated multi‑use path at the San Antonio interchange and said both interchanges would have bike facilities designed to avoid vehicle interactions. VTA deputy director Sahir Gulzada added that VTA is meeting with Mountain View and Palo Alto staff to secure local matching funds for future design phases.

Public engagement to date includes a November open house at the Mountain View Community Center and presentations to Mountain View BPAC; VTA said more than 50 people attended the open house and that feedback was “very positive,” with particular public interest in bike and pedestrian connections and questions about left‑turn/pedestrian interactions at San Antonio. VTA said it collected post‑COVID traffic data and plans to publish the traffic operations report and environmental documents for public review as they are completed.

VTA staff gave a tentative schedule: environmental clearance targeted by the end of the year and construction only if and when later phases are funded; VTA said, if funding is secured for later phases, construction could begin in 2028. Committee members pressed VTA to post the project slide deck and updated materials on the VTA project web page and asked VTA to provide a clearer funding breakdown; Chitraddi agreed to add the most recent slide deck and to provide more precise funding numbers at a forthcoming meeting with the city public works director.

No formal committee action or votes were taken on the project at this meeting; the presentation was an informational update and committee members and VTA staff discussed outreach, funding gaps, schedule uncertainty and technical design questions such as vertical clearance (existing bridges at the interchanges are about 15 feet where current Caltrans standard is approximately 16.5 feet).

Project partners cited during the presentation include Caltrans, the Cities of Mountain View and Palo Alto, and a local match from Google. VTA said the project would attempt to avoid free‑flow ramp movements inside Mountain View and would maintain crosswalks near driveways and destinations where feasible. The committee requested VTA post revised materials to the city and VTA web pages and to continue public engagement as the environmental document circulates.