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 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.


All construction / installation activities are complete and Caltrain is currently in the testing phase. The project team installed five subsystems; Data Communications System (DCS), Wayside, Backup Central Control Facility (BCCF), Central Control Facility (CCF), and onboard equipment. Each subsystem has a testing schedule and the level of visibility to the public varies by subsystem. For more information about specific noticeable testing efforts, please see the info below. 

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



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 
No anticipated activity this week. 

No anticipated activity this week. 

South San Francisco
No anticipated activity this week. 

San Bruno
No anticipated activity this week. 

No anticipated activity this week. 

No anticipated activity this week. 

San Mateo
No anticipated activity this week. 

No anticipated activity this week. 

San Carlos
No anticipated activity this week. 

Redwood City
No anticipated activity this week. 

Unincorporated San Mateo County
No anticipated activity this week. 

No anticipated activity this week. 

Menlo Park
No anticipated activity this week. 

Palo Alto
No anticipated activity this week. 

Mountain View
No anticipated activity this week. 

No anticipated activity this week. 

Santa Clara
No anticipated activity this week. 

San Jose
No anticipated activity this week. 



Caltrain Modernization Video (CBOSS PTC reference) 
Project Corridor Mailer Notifications
Action Steps Related to the APTA Peer Review
APTA Peer Review Report 

News Releases & Articles

Caltrain Terminates Contract with Parsons Transportation Group
Caltrain Video Details 'New Advanced Signal System' in Campbell Patch
PTC for the masses in Railway Age
Caltrain Releases Video Overview of New Advanced Signal System
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


JPB CBOSS PTC Presentation 7.7.16
JPB CBOSS PTC Presentation 2.4.16
JPB CBOSS PTC Presentation 11.5.15
JPB CBOSS PTC Presentation 9.3.15
JPB CBOSS PTC Presentation 8.6.15
JPB CBOSS PTC Presentation 5.7.15
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

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