An Introduction to
Positive Train Control

Metrolink works toward implementing system wide Positive Train Control

Positive Train Control (PTC) is a life-saving innovation that will make travel by rail even safer. Metrolink will be the first commuter rail in the nation to implement this state-of-the-art technology, moving the agency significantly closer toward its goal of becoming the safest commuter rail in the nation. 

Metrolink has taken the HOT (human, operational, technology) approach to PTC implementation, meaning the agency is not only focusing on the technology, but it is also concentrating on the human element behind it. The HOT approach means engaging Metrolink employees, contractor co-workers, and working in partnership with the Metrolink Board, regulators, labor unions, Amtrak, and Class 1 freight railroads to ensure successful implementation. It also means working toward a common, critical goal that will allow the people of Southern California to benefit from a life-saving enhancement that will revolutionize the railroad industry.

The successful implementation of PTC is highly dependent upon interagency coordination. Burlington Northern Santa Fe (BNSF), Union Pacific (UP), and Amtrak also operate on the 216-mile publicly owned portion of Metrolink's network, which means that the PTC system must be interoperable with each rail agency's operating systems to ensure continued smooth, uninterrupted train operations among each agency.


What is PTC?

Positive Train Control (PTC) is GPS-based safety technology capable of preventing train-to-train collisions, over-speed derailments, unauthorized incursion into work zones and train movement through switches left in the wrong position*. PTC monitors and, if necessary, controls train movement in the event of human error. PTC may also bring trains to a safe stop in the event of a natural disaster.

*Switches that are left in the wrong position will cause a train to deviate onto the wrong track. When this happens, a train runs the risk of colliding with another train or even derailing since it is going at a speed that is inconsistent with the unexpected course the train deviates to.


How will it work?

PTC sends up-to-date visual and audible information to train crew members about areas where the train needs to be slowed or stopped. This information includes the status of approaching signals, the position of approaching switches, speed limits at approaching curves and other reduced-speed locations, speed restrictions at approaching crossings and speed restrictions at areas where work is being performed on or near the tracks. PTC communicates with the train’s onboard computer, allowing it to audibly warn the engineer and display the train’s safe braking distance based on the train’s speed, length, width, weight, and the grade and curvature of the track. If the engineer does not respond to the ample audible warning and screen display, the onboard computer will activate the brakes and safely stop the train.


How much will it cost?

The estimated cost for developing, installing and deploying PTC on the Metrolink system is $210.9 million. Metrolink secured full funding from local, state and federal sources. Approximately 34 grants were secured.



Metrolink awarded a contract in October 2010 to Parsons Transportation Group (PTG) to design, supply, and install PTC technology throughout the 216-mile publicly owned portion of Metrolink’s 512-mile rail network.


Major hardware, software & firmware PTC components

There are many components that contribute to the PTC end-product. Here are descriptions of the major components, which will help you better understand how they work together to make PTC operable.


Back Office Server System

The PTC Back Office Server (BOS) System is the storehouse for the speed restriction, track geometry, and wayside signaling configuration databases.


Onboard System

The Onboard System is a combination of software and hardware that monitors and controls train movement if the engineer fails to respond to the audible warnings. The database information contained in the BOS is what’s used to calculate the safe braking distance that is provided to the train engineer. The Onboard System also displays train operations information.


Wayside Signal System

The existing Wayside Signal System houses the signal equipment, which is tied into Metrolink’s dispatching system and the switches that activate the red, green, and yellow signals the engineer heeds when operating the train. Wayside Interface Units (WIUs), PTC radios and GPS antennas must be installed along with hardware and software that will integrate the Wayside Signal System into the PTC System. The Wayside Interface Units and PTC radios will allow the Wayside Signal System to communicate with the BOS and Onboard systems, which through PTC can stop the train in the event of human error. Once integrated, the PTC System will perform a secondary check of the signal status and will stop the train if the engineer fails to heed a signal.


Communication Network Component

The Communication Network Component is a dependable, redundant wired and wireless communication network to connect components such as the locomotive and cab car, back office server and base stations, and wayside interface unit.


Computer-Aided Dispatching System

Metrolink’s existing Computer-Aided Dispatching (CAD) System is being replaced and integrated into the PTC system. The new system will interact with the PTC Back Office Server System to enforce a train’s authorization to occupy designated segments of track. Employees responsible for the protection and safety of workers performing work on or near the tracks will also have the ability to remotely communicate with the CAD system and the train engineer, via the train’s Onboard System, to notify the train engineer of approaching work zones.


Why is it being implemented?

PTC has been on the National Transportation Safety Board’s list of most wanted safety innovations since the early 1990s. On Sept. 12, 2008, a Connex engineer operating a Metrolink train failed to stop at a red signal, causing a collision with a Union Pacific freight train. In this tragic incident, 25 lives were lost and another 135 people were injured. California Senators Barbara Boxer and Dianne Feinstein led Congress in adopting the Rail Safety Improvement Act of 2008, which mandated the installation of PTC by the end of 2015. The Metrolink Board of Directors committed to implementing PTC in advance of the federal deadline to ensure Southern Californians are among the first in the nation to benefit from this life-saving technology.


Will PTC eliminate all rail incidents?

No. PTC will not stop a car from driving around lowered gates or prevent trespassers from making their way onto the tracks, but it will help prevent collisions like the one that happened at Chatsworth.


What is Metrolink’s target completion date?

Metrolink continues its push to install PTC ahead of the federal deadline. Challenges to complete PTC implementation remain, but Metrolink has achieved a number of critical milestones:

Most notably, in February 2014, Metrolink received authorization from the Federal Railroad Administration that it could begin operating PTC in Revenue Demonstration Service (RSD) under the authority of the BNSF Railway. On February 17, Metrolink ran the first successful RSD on the 91 Line, and on February 20, the PTC RSD was publically unveiled, with multiple VIPs and news media in attendance.

It is currently anticipated that Metrolink will conduct RSD on the San Bernardino Line in the fall of 2014, and that the entire system will be PTC operational by early to mid-2015, well before the current federal deadline of December 31, 2015.

Interdependency of rail carriers' national efforts to develop an interoperable system

PTC implementation requires coordination between Metrolink, Amtrak, North County Transit District (NCTD), along with Class 1 freight carriers BNSF Railway (BNSF) and Union Pacific Railroad (UP), which operate through the Southern California region to ensure interoperability across each agency’s system. Metrolink is also working with Class 1 freights Norfolk Southern Railway (NS) and CSX Transportation (CSX). Interoperability means continued smooth, uninterrupted train operations for each agency when they cross onto tracks operated by another agency. Interoperability is imperative because all agencies’ systems are interconnected. Metrolink shares tracks with Amtrak and freight carriers, and one-fifth of the tracks that both Metrolink and freight carriers operate on is single track. This presents a higher risk for collisions. PTC will help reduce such risks.



PTC Milestones

  September 2008

SCRRA Board of Directors directs the Chief Executive Officer to pursue funding for safety enhancements from the "North American Joint Positive Train Control Program" funded by the Federal Railroad Administration and any other sources of federal or state funding eligible for developing, implementing, or operating a Positive Train Control system for Metrolink.

  October 2008

The Rail Safety and Improvement Act of 2008 was signed into law, requiring installation of Positive Train Control systems.

  February 2009

SCRRA establishes organization to proactively develop and deliver PTC by December 2014.

  December 2009

SCRRA Board Approval of Competitive Negotiation Process and Evaluation Criteria.

  January 2010

The Federal Railroad Administration issues its final rule requiring railroads to install Positive Train Control technology.

  March 2010

SCRRA issues Request for Proposal (RFP) for the Vendor/Integrator component of the project.

  April 2010

SCRRA submits PTC Implementation Plan (PTCIP) to the Federal Railroad Administration, conducts pre-proposal meeting and issues addenda to bidders.

  May 2010

Federal Railroad Administration conditionally approves SCRRA PTC Implementation Plan.

  June 2010

Vendor/Integrator contractor(s) submit proposals; SCRRA evaluation begins.

  July 2010

Peer Review Session held. Negotiations with V/I proposer begin.

  October 2010

NTP issued to Vendor/Integrator.

  February 2011

PTC Development Plan (PTCDP) Variance Type Approval submitted to FRA.

  July 2011

Began on-board pilot installations.

  August 2011

Draft PTC Safety Plan submitted to the FRA for informal review.

  October 2011

Issue NTP to Communications Backhaul contractorr.

  February 2012

ETMS VII brake testing conducted on the BNSF San Bernardino Subdivision.

  July 2012

SCRRA Board approval of program budget increase to $210.9M and reset schedule, reflecting Revenue Service in September 2013, contract close-out by early 2014.
TCOSF design/build construction contract DB100R-12 awarded to USS Cal Builders

  October 2012

Change Order 020 executed, extending V/I contractor staff and facilities; contractual revenue service milestone to September 2013.

  November 2012

The Metrolink BOS is developed and released for testing (BOS 3.2M1 and M2). FRA witnessed SUBDIV file validation completed on the first subdivision (San Gabriel Sub).

  December 2012

PTC-CAD Part 1 is released. Integrated system testing (BOS to on board) begins in the lab.

  January 2013

Construction of San Gabriel Base Stations completed. Began signal validation pre-testing on San Gabriel Sub.

  February 2013

Construction of Valley Base Stations completed. FRA-witnessed SUBDIV file validation completed on Ventura and Orange subs.

  April 2013

Initiated construction of hardened facility to house dispatching and PTC.

  September 2013

Joint PTC Safety Plan with BNSF developed, began onboard installations at the Central Maintenance Facility.

  February 2014

Commencement of PTC Revenue Service Demonstration on the 91 Line.

Fact Sheets

For more background on PTC and other Metrolink safety initiatives, view our fact sheet:

PTC Safety Milestones