The Southern California Regional Railroad Agency (SCRRA) that operates the Metrolink regional commuter rail plans to implement a positive train control (PTC) system by 2012, ahead of the deadline set for the end of 2015. Implementation of the PTC system is required by the Rail Safety Improvement Act (RSIA) of 2008. The RSIA requires all Class I railroads, intercity passenger and commuter railroads to implement a PTC system on all main-line tracks where intercity passenger railroads and commuter railroads operate and where toxic-by-inhalation hazardous materials are transported.
The five county members of the SCRRA are jointly funding the development of an interoperable PTC system to improve safety for freight and commuter railroads in the region. PTC is designed to prevent train collisions using GPS tracking to remotely monitor train movements. In a typical PTC system, onboard equipment on the train uses GPS satellites to transmit speed and location data over wireless or hard line communications links to an operations center. A back office system at the operations center analyzes the data using software that determine the likelihood of a collision or derailment. An advance alert is sent by the dispatch center to the locomotive and brakes are automatically engaged if the warnings are not acted on by the train engineer. Federal regulations does not prescribe the type of technology a PTC system uses as long as it can accomplish the following functions: preventing train-to-train collisions, derailment from over speeding, incursions into designated work zone areas and train movements caused by switches left in the wrong position.