25th Avenue Grade Separation

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Rendering of the 25th Ave. GS Project

 Rendering of Completed 25th Avenue Grade Separation Project 

Background and Summary
Caltrain, in cooperation with the City of San Mateo, will raise the tracks and slightly lower the road (grade separate) at E. 25th Avenue in San Mateo. This will improve safety for both motorists and pedestrians, and it will reduce local traffic congestion in San Mateo. 

In addition to separating the tracks and road at E. 25th Avenue, the project will provide an opportunity to complete east-west street connections at 28th and 31st Avenues in conformance with the Bay Meadows Transit Oriented Development Plan.  

As part of the project improvements, Caltrain will build a new elevated Hillsdale Station located at E. 28th Avenue. The new station will offer updated amenities and will allow for better safety and reduced traffic. 

Schedule updated due to unforeseen conditions and utility conflicts during construction. 

Design: Completed December 2016
Right-of-way Acquisition: Fall 2016 to Spring 2017
Bid & Award: Winter 2016 to Summer 2017
Construction: Fall 2017 to Fall 2021

Project Cost  $205.9 million 

Measure A   $97.8 million
City of San Mateo   $14.1 million
State Section 190   $10 million
State HSR Prop 1A    $84 million

Community Impacts During Construction
Work to construct the grade separation began in fall 2017. As part of the project, Hillsdale Station closed in spring 2020 to allow for the building of 28th Avenue and a new elevated Hillsdale Station. The new station opened in April 2021, and more information about the station is available at

The work also requires the lowering of E. 25th Avenue between Palm Place and S. Delaware Street. This section of E. 25th Avenue is closed through summer 2021. Access to businesses on E. 25th Avenue will remain open during this time. 

To avoid impacting rail operations, some construction will take place during nights and weekends. Due to the nature of the construction, there will be temporary, localized noise impacts due to site clearing and construction activities.  

Public Involvement
Caltrain will be communicating with residents, businesses and other interested members of the public to discuss the project in more detail. Stakeholders will be provided with various opportunities to engage the project team and provide feedback prior to key milestones. For questions or concerns regarding this project, please call customer service at 1.800.660.4287 or email  

In keeping with the project’s goal of improving safety for all, on June 30, 2021, there was a virtual community meeting regarding the implementation of the Bicycle Master Plan-designated Class I bike facility planned for the northern sidewalk on E. 28th Avenue between El Camino Real and S. Delaware Street. View the presentation or watch the recording of the meeting, and see our Frequently Asked Questions for additional information. 

Project Resources

Information for Contractors

If you are a contractor and would like more information, please visit the San Mateo County Transit District's Bid and Contracts webpage here.