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“Positive train control” technology could have prevented the Amtrak derailment

Reuters/Lucas Jackson
Emergency workers search for bodies inside a derailed Amtrak train in Philadelphia, Pennsylvania, May 12, 2015.
  • Jeffrey C. Peters
By Jeffrey C. Peters

Systems Engineer, Purdue University

Published Last updated This article is more than 2 years old.

On May 12, 2015, a northbound Amtrak Northeast Regional Train 188 carrying 238 passengers to New York from Washington, DC, derailed near Philadelphia while entering a curve at almost twice the designated speed limit. Eight people were killed and more than 200 injured in an instant.

Questions about how the train derailed, why the train was traveling more than twice the posted speed limit, and how this could have been prevented surfaced immediately. Engineers typically have control over train speed, but the engineer of this particular Amtrak train currently reports having no recollection of the crash. Until the National Transportation Safety Board (NTSB) investigation is complete, we can only speculate on the root cause. However, we can discuss how this could have been prevented.

The promise of positive train control

Positive train control (PTC), a safety technology for rail transportation, may have been able to prevent this accident, and it is not the first time this sentiment has been echoed. In 2008, a similar accident prompted federal action.

On September 12, 2008, a passenger train collided with a freight train, resulting in 25 fatalities and 135 injuries in California. The engineer of the passenger train was distracted due to text messaging, and the NTSB specifically stated that PTC could have prevented this accident.

Within a month, the Railroad Safety Improvement Act of 2008 (RSIA08) became law and mandated that PTC must be implemented on about 60,000 miles of track, “providing regularly scheduled intercity or commuter passenger transportation” by the end of 2015. The abnormally fast response can be attributed to support from senator Barbara Boxer of California, who was chair of the senate committee on environment and public works at the time.

Unfortunately, the recent Amtrak accident came before the end of 2015 deadline, and this section of the Northeast Corridor did not have operable PTC. Further, it is highly improbable that the 2015 deadline will even be fully met.

While implementation of PTC is moving forward in some places, system-wide implementation continues to face significant barriers due to high costs, interoperability requirements and communication spectrum availability.

What is positive train control?

PTC from a functional perspective is a system designed to prevent train-to-train collisions, over-speed derailments, incursions into established work zone limits and the movement of a train through a switch left in the wrong position.

The technical aspects of these systems can vary, but they generally include a positioning system on each train and information on rules for sections of track, such as speed restrictions. There also has to be a way of communicating these data throughout the network. For example, PTC would override manual control if it sensed that the train was entering a section of track at double the posted speed limit.

Meteorcomm PTC
An example of a PTC system employed by major freight companies.

The potential safety benefits

Interest in PTC dates back to at least 1990, when the NTSB first placed it on its “Most Wanted List of Transportation Safety Improvements” where it is still regularly featured up to the most recent list in 2015.

The Federal Railroad Administration (FRA) estimated that between 1987 and 1997, an annual average of seven fatalities, 55 injuries, 150 evacuations and over USD$20 million in property damage could have been prevented by PTC. To put this in the context of the entire transportation network, there were 33,782 fatalities on the road network in 2012.

Although PTC is on NTSB’s “Most Wanted List” and many serious incidents due to human error could be prevented, the monetized safety benefits are significantly less than the costs. The FRA estimates the annual monetary value of the safety benefits from PTC to be about $90 million. The safety benefits may be slightly larger today, considering several serious accidents stemming from a boom in oil shipped via rail.

The costs

The law is an unfunded mandate, which means the costs of meeting the requirements are borne by the railroad operators. The FRA estimates that the total capital cost for full PTC deployment according to law would be about $10 billion (about one year’s worth of capital investments for the major US railroads) and annual maintenance costs of $850 million. While this investment might be feasible for major US freight rail companies, local and state governments with tight budgets will have a much more difficult time allocating funds for PTC.

The FRA established an annual $50 million grant program to help support the development of PTC, but the grant has been funded by Congress for only $3 million—well short of the total required cost of $2.75 billion estimated by the American Public Transportation Association.

Some argue that PTC could be used to optimize business operations with benefits up to $4 billion annually; however, this remains largely speculative.

Regardless of the federal mandate and possible future benefits, the costs of implementing PTC remain a significant barrier.

The systems integration barriers

In addition to costs, PTC has faced barriers in technical implementation, namely system interoperability and allocation of communication spectrum.

Interoperability is key in successful implementation of PTC. In the case of the Northeast Corridor, where the most recent accident occurred, Amtrak operates on both Amtrak-owned track and track owned by regional transit authorities and vice versa. Elsewhere, Amtrak operates on track owned by freight railroads. It is necessary to ensure that the systems developed by the freight railroads, Amtrak and regional authorities all communicate with one another. While interoperable systems have been developed, some issues persist.

Government Accountability Office, Amtrak
Track ownership and rail operations in the Northeast Corridor.

Another system integration issue is the acquisition of radio spectrum to support the communication demands of PTC. The Federal Communications Commission (FCC) generally holds auctions for spectrum, but allocates some for emergency services and government agencies.

However, the FCC so far has not addressed the needs of PTC. A consortium of railroad companies exists to purchase appropriate spectrum, but the amount of spectrum and the frequency are still uncertain – especially in highly congested areas in major cities, where choices in spectrum may be scarce. Without guidance from the FCC, obtaining spectrum and ensuring its interoperability is time-consuming and costly.

Going forward

It remains to be seen whether Congress will take immediate action following the Amtrak accident as it did with the 2008 accident in California.

House speaker John Boehner recently said it was “stupid” to claim that the slow rollout of PTC, which may have prevented the accident, is a problem with funding. He may be right that no federal money was cut for rail safety programs, but he also failed to mention that no money was given to help meet the unfunded mandate. Either way, it does not seem likely that local and state governments will receive much help in meeting the unfunded mandate.

Furthermore, a bill was introduced in the Senate this March to extend the PTC deadline to 2020 to help accommodate the cost, interoperability and spectrum barriers the railroads are facing. Perhaps then, the timing of this accident will lead to the failure of the bill and cement the 2015 deadline regardless of the financial and technical barriers.

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