PTC and passenger speeds

Ask Trains from the November 2015 issue
Amtrak’s 'Empire Builder' streaks through Brookfield, Wis. The speed limit for Amtrak on Canadian Pacific’s Watertown Subdivision is 79 mph.
Tom Danneman
Q Most Amtrak trains have a 79-mph speed limit. Will positive train control systems allow Amtrak to operate faster where track conditions allow? For instance, the Southwest Chief operates to 90 mph in places. Will PTC allow it to continue traveling this fast? – Seth Mangini, Bozeman, Mont.

A The short answer is, yes, positive train control systems will allow faster U.S. passenger trains to continue going fast. The Southwest Chief’s route uses automatic train stop as the primary train control system and assumes that crews responding to an alarm, based on signals only, will appropriately slow the train once they acknowledge the alarm by touching a control or pushing a button.

Positive train control systems that will replace ATS will slow or stop a train based on signals but also speed restrictions on curves, through work zones, and other places marked in geographic computer files. This makes PTC arguably safer than decades-old ATS. PTC systems are in place on higher speed routes in Michigan, Illinois, and along portions of the Northeast Corridor. Track speeds are also governed by track quality, whether the tracks are in a secure corridor, and the ability of a trainset to handle curves well. – Steve Sweeney
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