Positive Train Control (PTC)

What is PTC?

Positive Train Control, referred to as PTC, is a train safety system that is designed to prevent train accidents caused by human error.

The system utilizes a combination of wayside equipment, advanced onboard technology, GPS, and radio communication systems to automatically stop a train and prevent certain types of incidents:

  • Accidents or derailments caused by overspeed
  • Train-to-train collisions
  • Unauthorized train entry into work zones

In 2008, U.S. government mandated PTC to be implemented by railroad mainline handling hazardous materials or carrying passengers. The system was to be fully implemented by December 31, 2015. Congress extended the deadline by at least 3 years in late 2015. The current deadline to have PTC fully implemented is December 31, 2018 with the possibility of 2 additional years.

How does PTC Work?
PTC’s onboard systems analyze a train’s location along its route using GPS and track data. The system contains “rules” about the train’s route including speed limits, operating restrictions, and track conditions. With that data, the PTC system evaluates the train’s distance from the nearest signal, such as a speed restriction. 

PTC considers the distance between the train’s current location and the signal, the train’s speed, and the estimated time it takes the train to stop. Using that logic, PTC calculates the point at which the engineer should begin to apply the train brakes. If the engineer does not begin braking, a warning appears on a screen inside the cab of the locomotive. The system gives the engineer time to react and bring the train to the correct operating speed or to stop.

If the engineer does not stop or slow the train within the warning period, PTC automatically applies brakes to stop the train.

Wi-Tronix & PTC

Wi-Tronix offers the Violet solution that monitors PTC system health, logs PTC alerts and messages, and provides asset information in real time to improve remote monitoring for everyday operations and investigations. 

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