Improved air quality could be another plus of a railroad safety system known as PTC

By the end of the year, about 70,000 route-miles of railroad track in the United States are mandated to be outfitted with a fully functioning Positive Train Control or PTC system. Both in 2015 and 2018, expressed PTC mandates for those two years were not met. Will it be the same regarding the 2020 deadline?

Irrespective, future high-speed rail endeavors such as the one being built in California and the two currently in the planning stages and proposed for the Golden/Silver and Lone Star states (that’d be XpressWest’s and Texas Central’s respectively), likewise require PTC’s application and implementation.

Besides it being a safety technology utilized to prevent train-to-train head-on and rear-end collisions, PTC will, where deployed, make impossible incursions of so-equipped trains into railroad work zones plus keep over-speed situations from occurring, which absent that capability, could result in train crashes and derailments. And, with the understanding that PTC deployment and use will make railroad operations overall more efficient, the thinking is that this will lead to air quality improvement where trains operate in that there will be greater efficiencies realized which will mean less fuel consumed and fewer emissions produced. And, by virtue of that, such will improve affected railroad company bottom lines.


Such mandating of US-based PTC all came about because of one tragic incident and that one alone.

That incident? The 4:22:23 p.m. Sept. 12, 2008 head-on of one Metrolink passenger train and a Union Pacific freight on a curved section of track in Chatsworth, California that in its wake left 25 people dead and 135 maimed, injuries ranging from slight to moderate to severe. Based on what had transpired, the overarching belief at the time was that with a properly functioning collision-avoidance protocol in place and performing as designed and specified, this one truly unfortunate circumstance could have been prevented, meaning it did not have to happen. It was this incident and this one alone that got Congress to act.

Being called for is field-deployment of an error-free PTC system capable of providing collision, over-speed and work-zone-incursion protection for thousands of trains operating on some 70,000 route miles of track.

Two previous deadlines (Dec. 31, 2015 and Dec. 31, 2018) for this safety system to be installed and activated came and went. As to the deadline this go-’round: Will the industry meet or miss this one too? That’s the $13 billion question.

The backstory: PTC’s earlier cousin – Automatic Train Stop (ATS)

As far back as the 1950s a number of U.S. railroad companies made use of a technology known as Automatic Train Stop (ATS).

“The Congressional” with PRR GG1 in charge

The version employed on and utilized by the Pennsylvania Railroad incorporated into it a cab-signaling component that the locomotive engineer would use to monitor conditions on the track ahead. If there was a conflict of any type such as that of a train approaching on the same track from the opposite direction and a collision would be imminent if intervening, corrective action to prevent such wasn’t taken, the ATS system was designed to prevent those two trains from colliding and either train or both would automatically be slowed and then brought to a full stop – hence the name Automatic Train Stop – in the event that one or both engineers failed to react to and respond appropriately and thus slow and/or bring their respective trains to a halt.

The way the system worked was through an electronic signal that was transmitted through the rails that was picked up via a receiver of sorts attached to locomotive wheel assemblies, the track-condition information continuously monitored and analyzed, while the visual representation (otherwise known as an “aspect” in this case) of that track condition was displayed on the cab-signal element inside the locomotive that both engineer and brakeman could see.

If in the event an unsafe operating condition presented itself and the locomotive engineer did not make the corresponding appropriate speed reduction in terms of appropriately and properly reacting to that unsafe condition within a period of six seconds, not only would an audible whistle warning be initiated, but proper automatically-initiated locomotive and/or train brake application(s) would be made.

Example of signal bridge-mounted signals in background on the Central Railroad of New Jersey in 1969

With this type of system in place, a restrictive signal such as that of a red aspect which indicates “stop,” could not be breached.

The reason these systems on most if not all Class I railroads did not withstand the test of time and remain in place, is most probably because of economic hardships the railroads faced beginning in the 1960s and lasting well into the ’70s. The railroads simply did not have the capital needed to operate and maintain what, for them, had become cost-prohibitive systems. While in use though, these ATS system apparatuses no doubt prevented catastrophe and injury and loss of life.

For the most part as a result, this capability and technology fell by the wayside.

Images: Environmental Protection Agency (upper); Association of American Railroads (middle); Roger Puta, Wikimedia Commons (lower)

This post was last revised on Sept. 7, 2020 @ 11:24 a.m. Pacific Daylight Time.

Published by Alan Kandel