Advanced Signal System Project - CBOSS PTC


The Communications Based Overlay Signal System (CBOSS) Positive Train Control (PTC) Project is an Advanced Signal System that will equip the corridor with federally-mandated safety technology by December 2015 and increase system capacity to help accommodate future increases in ridership demand. The Advanced Signal System will be interoperable with all other rail systems that access the Caltrain corridor, including commuter rail, freight rail and, in the future, high-speed rail.

The Advanced Signal System is a key component of the Caltrain Modernization Program that will electrify and upgrade the performance, operating efficiency, capacity, safety and reliability of Caltrain’s commuter rail service, providing Peninsula communities with a modernized rail service that will help meet growing ridership demand between San Francisco and San Jose.


Improved Safety

The Advanced Signal System will monitor and, if necessary, control train movement in the event of human error. This will increase safety on the Caltrain corridor, which has over 40 at-grade vehicular and pedestrian crossings by:

  • Eliminating the risk of train-to-train collisions.
  • Reducing risk of potential derailments by enforcing speed limits.
  • Providing additional safety for railroad workers on the tracks.

Increased Reliability and Operating Performance

The Advanced Signal System will also provide more dependable passenger service and operating performance, which will be achieved by:

  • Schedule management – there will be better accountability and management of train schedules.
  • Enforcement of scheduled station stops – a train will no longer be able to overshoot a station stop or platform.
  • Improved grade crossing performance - travelers crossing the tracks will benefit from reduced gate downtime and improved local traffic circulation.

Capacity Benefits

Current Caltrain capacity is constrained by the existing wayside signal system, which enforces a safe separation between trains based on the poorest performing train type. The Advanced Signal System will improve on this system. It will minimize the separation of trains based on the safe braking requirements of specific train types. Caltrain Electrification will combine the Advanced Signal System project with the operation of high-performance electric multiple unit (EMU trains) and will upgrade the system to provide faster and/or more frequent service to more stations and riders.

To learn more, view the fact sheet and Frequently Asked Questions.


Installation activities are currently underway to implement the project. Installation activities cover five subsystems of the project: Data Communications System (DCS), Wayside, Backup Central Control Facility (BCCF), Central Control Facility (CCF), and onboard. Each subsystem has an installation and testing schedule and the level of visibility to the public varies by subsystem. The activities that will be most noticeable to the public relate to the DCS installation and testing.

For more information about the DCS installation, which includes installation of conduit, fiber optic cable and base stations within the Caltrain right-of-way, view the following fact sheets:

The other subsystems involve installation activities that are less visible to the public such as installing equipment onboard trains and reconfiguring office space to house critical dispatch and monitoring equipment.

Click on your city for more information about current installation activities:

Caltrain CBOSS Overview
San Francisco Brisbane South San Francisco San Bruno Millbrae San Mateo Belmont San Carlos Redwood City Unincorporated San Mateo County Atherton Menlo Park Palo Alto Mountain View Sunnyvale Santa Clara San Jose



timeline graphic


The Advanced Signal System project is funded through a combination of local, regional, state, and federal sources. The specific funding sources are:

  • $71 million in local funds from San Francisco, San Mateo, and Santa Clara counties.
  • $113 million in state funds including $106 million in High Speed Rail Connectivity Funds..
  • $47 million in federal funds.

The budget will be allocated across the below costs:

Project Cost
PTG Base Contract with Fiber Option
$138 million
JPB Project Management Oversight and Other Direct Costs (ODCs) including Taxes and Facility Lease
$48 million
Options and Allowance (Spectrum purchase, additional Warranty, spares, etc)
$34 million
$11 million
$231 million


View the CBOSS PTC photo gallery here.

Installing New Wires at the Rear of the Entry Rack - March 2014


Below are details about anticipated installation impacts as part of the work activity scheduled to occur this week:

San Francisco 
Day work will occur June 1 - 5, from 7 a.m. to 5 p.m., to identify utility lines and install/test fiber optic cable.

Night work will occur May 31 –June 4, from 8 p.m. to 6 a.m. Crews will be boring and/or digging a small trench and installing conduit for fiber optic cable. Lights will be used in the area to provide visibility. Neighbors may experience some minor installation noise during this time. Crews will work as quietly as possible.

A bus bridge will be in service on June 6-7 between the Bayshore, 22nd Street, and San Francisco stations to allow crews to install fiber optic cable in the four San Francisco Caltrain tunnels. The bus bridge schedule for that weekend is available online here

No scheduled installation activity.

South San Francisco 
No scheduled installation activity.

San Bruno
Day work will occur June 1 - 5, from 7 a.m. to 5 p.m., to identify utility lines and install/test fiber optic cable. Crews will also be installing fiber optic cable on either side of the San Bruno Caltrain station.

No scheduled installation activity.

No scheduled installation activity.

San Mateo 
No scheduled installation activity.

No scheduled installation activity.

San Carlos 
No scheduled installation activity.

Redwood City 
No scheduled installation activity.

Unincorporated San Mateo County 
No scheduled installation activity.

No scheduled installation activity.

Menlo Park 
No scheduled installation activity.

Palo Alto 
No scheduled installation activity.

Mountain View 
No scheduled installation activity.

No scheduled installation activity.

Santa Clara 
No scheduled installation activity.

San Jose 
No scheduled installation activity.

View Project Corridor Mailer Notifications for past outreach materials.

For more information/Para más información:

Email: or
Call: (650) 508-6499
To subscribe to page updates, please click here.

Additional Resources

Fact Sheet
Installation Fact Sheet
Noise and Light Fact Sheet
Frequently Asked Questions

Caltrain Modernization Video (CBOSS PTC reference):
Project Corridor Mailer Notifications

News releases & Articles

Caltrain to Operate Bus Bridge June 6 & 7
Caltrain on Track to Install Positive Train Controls
FRA green-lights CBOSS PTC in Railway Age  
Caltrain Receives FRA Approval to Proceed with New Positive Train Control System
Caltrain Modernization Program in Transportation & Infrastructure
Caltrain Modernization Kicks Off Advanced Signal System Work 
Community Leaders Rally Support for Caltrain Modernization’s $20 Million Grant Application
Federal Grant Moves Modernization of Caltrain Corridor Forward

LPMG CBOSS PTC Installation Update Presentation 3.27.14
LPMG CBOSS PTC Installation Update Presentation 9.26.13
JPB CBOSS PTC Installation Presentation 9.5.13
LPMG CBOSS PTC Installation Presentation 8.22.13
LPMG CBOSS PTC Overview Presentation 3.28.13
JPB CBOSS PTC Presentation

Federal Mandate:
In response to a fatal train collision in September, 2008, Congress passed the Rail Safety Improvement Act (RSIA) of 2008 which updated the Code of Federal Regulations (CFR) to require PTC to be installed along every passenger rail corridor prior to December, 2015. More information is available here.

6/13/14- CF/rjc

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