Railroads and the federal government faced off against each other this year over when Positive Train Control would be implemented.

Originally the technology was mandated to be installed on mainlines that carry toxic or hazardous-by-inhalation chemicals or any regular passenger traffic. PTC was ordered under the Railroad Safety Improvement Act of 2008 and established a deadline for the implementation of PTC on Dec. 31, 2015.

Since the act went into law several problems presented themselves such as needing radio spectrum space for transponders. According to the American Association of Railroads, 11,000 out of 62,000 miles and 9,000 locomotives had PTC systems installed by the end of this year.

In August the Federal Railroad Administration outlined fines that would be issued for PTC violations, while in September a Surface Transportation Board chairman said that railroads could ignore their common carrier obligations for safety reasons. Days after the statement major carriers threaten to do just that.

On Sept. 9, Union Pacific, Norfolk Southern, and BNSF Railway publicized letters that they had sent to U.S. Sen. John Thune of South Dakota. The letters said that the railroads would start to embargo freight before Thanksgiving, commuter operations would cease before midnight on Dec. 31 and long-distance passenger trains would halt several days before New Year’s Eve.

Shippers said that congress needed to act on extending the deadline. In late October congress inserted the PTC extension into the Surface Transportation Act of 2015. The new deadline gives railroads until Dec. 31, 2018, but also requires railroads to submit revised PTC installation plans to the FRA within 90 days of the bill’s passage.

For the last 10 (business) days of the year, Trains editors will present the Top 10 stories of the year in reverse order starting Dec. 16 and finishing on Dec. 31.