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Positive Train Control

According to the Federal Railroad Administration:

"In 2008, Congress required Class I Railroad mainlines handling poisonous-inhalation-hazard materials and any railroad main lines with regularly scheduled intercity and commuter rail passenger service to fully implement Positive Train Control by December 31, 2015. PTC uses communication-based/processor-based train control technology that provides a system capable of reliably and functionally preventing train-to-train collisions, overspeed derailments, incursions into established work zone limits, and the movement of a train through a main line switch in the wrong position.

"In late 2015, Congress extended the deadline by at least three years to December 31, 2018, with the possibility for two additional years if certain requirements are met. The new legislation, the PTC Enforcement and Implementation Act, required that railroads submit a revised PTC Implementation Plan (PTCIP) by January 26, 2016, outlining when and how the railroad would have a system fully installed and activated."

There are no formally-adopted standard frequency bands or designated frequencies for PTC, although frequencies in the ~220 MHz range are becoming the de facto standard. PTC may make use of channels belonging to various services spanning the 217-222 MHz range, including frequencies allotted for the 218-219 MHz Service (formerly the Interactive Video and Data Service (IVDS)) and the Automated Maritime Telecommunications System (AMTS). In fact, the challenge of obtaining sufficient spectrum is one of the reasons cited for delayed implementation of PTC.