Positive Train Control
Rail Safety Improvement Act
In October 2008, President George W. Bush signed the Rail
Safety Improvement Act into law. This Act calls for a number of rail safety improvements including:
• Positive train control
• Highway rail grade crossing safety
• Dark territory safety enhancements
• High speed rail improvements
About PTC
Positive train control (PTC), one tenet of the legisilation, is a system of monitoring and controlling train movements to provide increased safety. According to the Rail Safety Improvement Act, there are four aspects that the railroads must address with a PTC system:
• Prevent train to train collisions
• Prevent over speed derailments
• Prevent incursions into established work zone limits
• Prevent the movement of a train through a switch left in the improper position
The Act states that PTC will be required on 1) main lines (when there is five million gross tons per year on a track) over which is transported: a) any quantity of poison – or toxic-by-inhalation hazardous materials, or b) where there is intercity passenger service or 2) lead locomotives operating on any territory that requires PTC installation. The final implementing rule verbiage related to all of the above is still under debate within the Federal Railroad Administration (FRA) with more explicit definitions pending. The result, however, is that PTC will likely be required on more than 70-90% of main line trackage within the United States
The Acts also mandates that the PTC system be interoperable where there is a need such that any railroad's locomotive could operate over any other railroad's infrastructure using the same signaling/control systems. This can be a difficult task due to varrying operational methods, communications infrastructure, signaling philosophies, etc. between North American railroads.
Finally, PTC must be fully operational by December 31, 2015. However, the railroads must submit PTC implementation plans, including a product safety plan and other documentation, to the FRA by April 2010.
The main concept in PTC (as defined for North American Class I freight railroads) is that the train receives information about its location and where it is allowed to safely travel, also known as movement authorities. Equipment on board the train then enforces this, preventing unsafe movement. PTC systems will work in either dark (non-signaled) or signaled territory and often uses GPS navigation to track train location.
