National Transportation Safety Board Member Jennifer Homendy called on U.S. railroads Tuesday to fully implement Positive Train Control (PTC).

At a press event in New Haven, Conn., with Senator Richard Blumenthal and rail advocates, Homendy pushed for railroads to fully implement PTC, a safety system designed to prevent train-to-train collisions, overspeed derailments, switches left in the wrong position, and incursions into established work zone limits.

“In the past half century, the NTSB has investigated more than 150 PTC preventable accidents that have taken nearly 300 lives and injured about 6,700  others,” Homendy said. “The NTSB’s message is simple: no more extensions, no more excuses, and no more delays. Finish the job.”

The press event coincided with the 50th anniversary of a train collision in Darien, Conn., that killed four people and injured 43 others. The NTSB issued its first recommendation related to PTC as a result of its investigation of the Darien accident.

In 2008 Congress mandated the installation of PTC. The initial deadline for PTC was December 2015. That deadline was extended to 2018. With additional conditions met, some railroads now have until 2020 to fully implement PTC. The NTSB has asked that no further extensions be granted, which is why fully implementing PTC is on the NTSB 2019-2020 Most Wanted List of Transportation Safety Improvements.

Many railroads have made significant progress and have spent billions of dollars to implement PTC, improving the safety of many tracks and trains. Although the vast majority of railroads have completed work to install PTC on their track and locomotives, only 16% of Class I railroads, 19% of intercity passenger railroads, and 29% of commuter railroads report that they have made their PTC system interoperable with other systems.

Passenger trains frequently operate on track owned by other railroads, which is why interoperability is required for a fully operational PTC system.

“Today is about remembering Darien,” said Homendy. “And there’s no better way to put that memory into action than to complete the implementation of PTC.”