The existing US 101/SR 25 interchange, located just south of Gilroy in Santa Clara County, is over thirty years old. It cannot accommodate traffic demands due to rapid growth in commuter, commercial, and recreational traffic that passes through this area. These conditions, coupled with high travel speeds, have resulted in higher-than-average accident rates in the interchange area, and traffic backups onto southbound US 101.
This Phase 1 project sets the stage for future implementation of the overall interchange reconfiguration slightly north of the current interchange. Phase 1 will...
The existing US 101/SR 25 interchange, located just south of Gilroy in Santa Clara County, is over thirty years old. It cannot accommodate traffic demands due to rapid growth in commuter, commercial, and recreational traffic that passes through this area. These conditions, coupled with high travel speeds, have resulted in higher-than-average accident rates in the interchange area, and traffic backups onto southbound US 101.
This Phase 1 project sets the stage for future implementation of the overall interchange reconfiguration slightly north of the current interchange. Phase 1 will accommodate future improvements to US 101, SR 25, and SR 152, and provide a connection point at the interchange for a future Santa Teresa Boulevard extension from Castro Valley Road. The proposed Phase 1 project is funded by 2016 Measure B and SB1.
Final Design Map
Objectives
- Improve connectivity between US 101 and SR 25
- Improve traffic operations along US 101 and SR 25 with added ramp storage and signals
- Enhance safety within the interchange area by reducing ramp backups onto southbound US 101 and providing improved access for safer merges
- Support the overall future interchange reconfiguration, including US 101 and SR 25 widening, and future SR 152 improvements between US 101 and SR 156
Project Features
Phase 1 will reconstruct the US 101/SR 25 interchange slightly north of the current interchange.
- Replace the SR 25 two-lane overcrossing with a four-lane overcrossing spanning across US 101
- Increase the length of the southbound US 101 off-ramp to SR 25 to decrease traffic back-ups onto US 101
- Upgrade the northbound US 101 ramps to improve exit and merging operations
- Install new traffic signals at the ramp intersections to improve traffic flow
- Construct a separated 2-way bikeway between Castro Valley Road and the southbound 101/SR 25 intersection.
As additional funding becomes available, future phases of interchange improvements will be scheduled. These future upgrades include converting the interchange to a partial cloverleaf or diamond ramp configuration with potential direct connectors, frontage roads for local and bicycle access, and grade separating SR 25 from the Union Pacific Railroad east of US 101.
The overall project is included in the Valley Transportation Plan (VTP) 2040 Highway Program.
Community Outreach
Mobility Partnership Committee
Quarterly updates are provided to the Mobility Partnership Committee. The Mobility Partnership provides policy oversight and direction to VTA staff and the Council of San Benito County Governments regarding potential mobility improvements between US 101 and I-5 in southern Santa Clara and northern San Benito Counties. The meetings will be streamed through Zoom.
Mobility Partnership Meetings (2025):
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March 12, 2025 9:30 AM at the San Benito County Board of Supervisors Chambers 481 Fourth Street, Hollister, CA .
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May 21, 2025 9:30 AM at the San Benito County Board of Supervisors Chambers 481 Fourth Street, Hollister, CA .
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August 20, 2025 9:30 AM at the San Benito County Board of Supervisors Chambers 481 Fourth Street, Hollister, CA .
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November 19, 2025 9:30 AM at the San Benito County Board of Supervisors Chambers 481 Fourth Street, Hollister, CA .
Online Community Meeting
In case you missed the June 9, 2021, online meeting, watch a recording of the presentation on the VTA YouTube Channel. View the presentation slides here.
Frequently Asked Questions
*Last Updated 2/18/205
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Why was it decided to close the access of southbound US 101 from Mesa Road and Castro Valley Road?
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Originally, plans included a new connection to Santa Teresa Blvd. However, due to current funding constraints, this component could not be included.
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During the design phase, VTA explored various options to connect Castro Valley Road to the new US 101 off-ramp to SR 25, but none met Caltrans' safety standards and were not approved.
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To enhance safety and alleviate congestion on southbound US 101, the new off-ramp to SR 25 will be extended significantly. Consequently, the existing US 101/Castro Valley Road intersection must be closed. Additionally, due to safety concerns regarding sight distance, the intersection at US 101/Mesa Road will also be closed.
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Caltrans, VTA, and the City of Gilroy recognize the importance of the future Santa Teresa Blvd Extension. VTA has secured funding to initiate the environmental phase in 2025 and continues efforts to secure additional funding for design and right-of-way acquisition. Construction is projected to commence in 2029 pending full funding.
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For more information on this project, please visit the Santa Teresa Blvd Extension Project.
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Is the extension of Santa Teresa Boulevard part of this project?
- VTA agrees that the Santa Teresa Boulevard extension from Castro Valley Road to State Route 25 is an important feature of the ultimate US 101/ SR 25 interchange. VTA is actively seeking funding from federal grants to be able to develop and implement this project and potentially supplement the project through the SB1 Trade Corridor Enhancement Program (TCEP) and the 2016 Measure B sales tax funds.
- Currently the environmental phase is fully funded with a combination of Federal and VTA 2016 Measure B funds.
- The project can begin with the environmental clearance phase in 2024.
- Please subscribe to the SR 152 Trade Corridor, the US 101/SR 25 Interchange, and the Santa Teresa Boulevard Extension Project projects to receive updates on this phase of the project.
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Why is the proposed northbound 101 exit to eastbound 25 going under the overpass?
- To improve safety and comply with design standards, the proposed northbound 101 off-ramps for the US 101/SR 25 Interchange Phase 1 project will be lengthened to provide more deceleration distance before the first sharp curve on the off-ramp as compared to existing conditions. This off-ramp is located next to a protected creek and historical site that cannot be impacted based on the environmental approval previously obtained for the project.
- Because of these constraints, and to reduce the right of way take and not shift the proposed SR 25 overcrossing further to the north, the northbound off-ramp extends underneath the SR 25 overcrossing before looping back to the intersection with SR 25.
- Routing the northbound off-ramp along the south side of the proposed SR 25 alignment would complicate the project's stage construction since that is the area of the existing SR 25 on the embankment that would need to be removed before the ramp is built.
- Additionally, it would be difficult to taper this third lane to eastbound SR 25 to the single lane that is required before the Union Pacific Railroad crossing. Both the Phase 1 and ultimate interchange configurations propose signalizing the northbound US 101 ramps/SR 25 intersection to control traffic operations.
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There is a concern for the closure of Mesa Rd. during and after construction, and the community impact it will cause to farm property and rental property along Mesa Rd. How will this closure, and the project impact those rentals? Will the renters have to leave?
- Impacted properties along Mesa Rd at US 101 have been offered compensation for the changes proposed by the Phase 1 project. No property owners or renters along Mesa Rd must leave because of the Phase 1 project.
- The proposed future Santa Teresa Extension project will provide new connectivity between Santa Teresa Boulevard and the US 101/SR 25 interchange that travelers along Castro Valley Rd and Mesa Rd can use.
How to Reach Us
For more information on this project, please call VTA’s Community Outreach at (408) 321-7575, (TTY) 408-321-2330, or community.outreach@vta.org.
Environmental Documents
The following PDFs are available to view and/or download. The 2013 Final EIR is provided as a full document, or as smaller chapters for your convenience. The Addendum to the Final Environmental Impact Report for the U.S. 101 Improvement Project between Monterey Street and State Route 129 Project was completed in 2013. The Addendum addresses Phase 1 of this project. The Addendum is focused on an evaluation of the Phase I Project and design changes to the US 101/SR 25 interchange. On June 2, 2022, VTA's Board of Directors will consider approving the Addendum.
Addendum to Environmental Documents
2013 Final EIR: Cover, Summary, Table of Contents
Timeline
Title
Design
Phase Date Range
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Traffic congestion may be lighter since the start of pandemic-related shelter-in-place orders, but we all know it’s going to come back someday. Read more.
The proposed project funded by 2016 Measure B and SB1 is the first phase of the larger US 101 Improvement Project between Monterey Road and the SR 129 project. Read more here.
Watch a recording of the presentation on the VTA YouTube Channel. View the presentation slides here.
The June 9 virtual meeting to discuss the US 101/SR 25 Phase 1 Project drew dozens of interested attendees. You can click here to read more about what's planned, and below is a review of some of the questions that were answered at the on-line meeting. Read more here.
The Addendum to the Final Environmental Impact Report (FEIR) for the U.S. 101 Improvement Project between Monterey Street and State Route 129 Project has been prepared for Phase I of this project.
Gilroy City Council Chambers 7351 Rosanna Street, Gilroy, CA. Access the Agenda
VTA tabled the City of Morgan Hill's National Night Out event to promote the 101/SR 25 interchange project. The National Night Out event is an annual, community-building campaign that promotes police-community partnerships.
San Benito County Board of Supervisors Chambers 481 Fourth Street, Hollister, CA. Access the Agenda
The Mobility Partnership meeting was held at the City of Morgan Hill Council Chambers 17575 Peak Avenue, Morgan Hill, CA. Click here to see the meeting agenda and presentation slides.
The 9:30 AM Mobility Partnership meeting will be held at the San Benito County Board of Supervisors Chambers 481 Fourth Street, Hollister, CA. Click here to see the meeting agenda and presentation slides.
Title
Construction
Phase Date Range
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3/12/25, OPEN HOUSE Registration Link here
- Date & Time: March 12, 2025, at 6:00 PM
- Location: Gavilan College - Student Center Lounge (5055 Santa Teresa Boulevard, Gilroy)
- Free Parking at Lots E or F
- Bus Routes: Route 86
- *Spanish interpreters will be available at the VTA public meeting
- *Campus Map link click here
3/13/25, OPEN HOUSE Registration Link here
- Date & Time: March 13, 2025, at 6:00 PM
- Where: Gilroy Library, Community Room (350 W. Sixth Street, Gilroy)
- Bus Routes: Route 86
- *Spanish interpreters will be available at the VTA public meeting.
3/26/25, Meeting – Online Registration Link here
- Date & Time: March 26, 2025 at 6:00 PM
- Zoom Link: https://us02web.zoom.us/j/87434744208?pwd=UjlK0RGSQNwMtpoCPNU48idUrcag1t.1
- *Spanish interpreters will be available at the VTA public meeting.
We encourage you to register for one of these meetings. With pre-registration, you will receive meeting reminders and project updates by e-mail.
