What is positive train control?

How does it work?

The speed and location of trains are tracked through a combination of GPS systems, computers installed on board the locomotives and radio equipment installed along the railway wayside. PTC systems overlay existing railroad hardware and software. When a train is running at a speed or in an area where it shouldn’t be, a warning signal is first sent to the engineer. If the engineer does not respond, the train brakes automatically. 

What gave rise to PTC? 

On Sept. 12, 2008, a collision in Chatsworth, California, killed 25 people and injured 135 others. The collision took place when an engineer of a Metrolink passenger rail system was texting. That distraction led to a collision with a Union Pacific freight train. The following month, Congress passed the Rail Safety Improvement Act (RSIA) of 2008 and President George W. Bush signed it into law. The RSIA mandated PTC for the majority of locomotives and track in the United States; the exception was the minority of track and locomotives that do not come in contact with passengers or hazardous materials. 

The initial deadline for implementing PTC was Dec. 31, 2015. The deadline was extended by three years to Dec. 31, 2018, which also included an extension of an additional two years to year-end 2020 with the approval of the Department of Transportation, provided certain parameters were met by year-end 2018.

As of Dec. 31, 2020, all the railroads required to implement PTC systems had done so, including all the U.S. operations of the Class I railroads, according to FRA.

How have the railroads described PTC since it became mandated? 

In the years immediately following the RSIA, the management teams of the Class I rails largely bemoaned PTC as an “unfunded mandate” since the railways were expected to finance multibillion-dollar PTC capital expenditures themselves without a credit from the federal government. The railways also expressed concern that PTC would reduce railway capacity because it would make railway operations overly conservative, requiring excessive space between trains, or provide “false positives” and stop trains unnecessarily.

But in recent years, the Class I railways changed their tone on PTC. Instead, they have highlighted the potential improvements to efficiency that PTC may give rise to with the railways’ newfound PTC-related data. 

PTC “has created an additional layer of safety to the rail network that can safely bring a train to a stop before certain types of human-error accidents can occur. The charge of being able to bring a train to a safe stop may sound simple, but the technology and the effort necessary to bring PTC to life was not,” the Association of American Railroads (AAR) told FreightWaves.

AAR continued, “To meet that charge, railroads had to be able to first precisely track a train’s location, speed and direction across the network. This required installing hundreds of thousands of components, building a secure communications network among many other tasks. Beyond that, the automatic braking technology had to work seamlessly across other railroads’ operations requiring rigorous testing and industry-wide cooperation.”

What’s next after PTC? 

The freight rail industry is looking at whether trains could run closer together as a way to increase capacity. The industry is also examining how PTC-related data could instruct the railways on how to more efficiently balance their networks.

“With the technology fully deployed, railroads now have detailed geo-mapping, advanced communications systems and modernized locomotive systems that can be used as a springboard for future innovation. Future rail innovation will undoubtedly have its roots in PTC,” AAR said.

FreightWaves reporter Joanna Marsh contributed to this report.