Metrorail work vehicles operate with no protection to keep them from running a red signal or entering an occupied section of track. This leads to safety issues as well as operational difficulties in the movement of work trains throughout the Metrorail system. Should that be changed with the installation of automatic train protection hardware on work vehicles?
The Metrorail system depends on diesel-powered rail vehicles (which WMATA refers to as “prime movers”) to move work trains, conduct snow removal, move passenger trains in contingency situations, and perform other functions. Prime movers, as well as other work vehicles on the Metrorail system (like a Sperry Rail Service car, etc.) are referred to in the Metrorail Safety Rules and Procedures Handbook (hereinafter MSRPH) as “Class II” rail vehicles. Passenger cars on the system are designated “Class I” rail vehicles.
In contrast to Class I vehicles, prime movers are not equipped with ATP, meaning that there is no means whatsoever of signal enforcement. Unlike older subway systems in Toronto, New York, London, and other cities, the Metrorail system does not use mechanical trip stops for signal enforcement. Instead, signal enforcement is provided only by speed commands transmitted to trains through coded track circuits. On Class I Metrorail vehicles, automatic train protection, or ATP, is provided by equipment which stops the train when it encounters a zero speed command. Moreover, the only wayside signals on the Metrorail system are found at interlockings. Between interlockings, there’s no way for the crew of a work vehicle to know the status of the track ahead. As such, work vehicles on the Metrorail system are at a real disadvantage. To provide some measure of protection to work vehicles, the Metrorail OCC will establish an “absolute block”, defined in the MSRPH as “a section of track between two specific locations into which no train is permitted to enter while it is occupied by another train”. There’s a catch, though. A Class I vehicle approaching an absolute block will get a zero speed command (and, if the block encompasses an interlocking, see a red signal), but as previously noted, there’s no signal enforcement for Class II vehicles. In addition, operating trains under absolute block is a labor-intensive process. They must be manually placed and removed by OCC operators, and moved ahead of rail vehicles as they traverse the mainline. The MSRPH indicates that “the absolute block shall not exceed 3 consecutive stations for movement of non-revenue vehicles”. So, this brings us to the question posed in the title of this post: should Metrorail work vehicles be equipped for ATP?
Doing so provides a number of advantages. First and foremost is the safety benefit of providing signal enforcement for work vehicles. In New York, for example, diesel locomotives used to move work trains on the subway are fitted with tripcocks just like passenger trains. Additionally, pending MSRPH revision, work vehicles could be permitted to travel at mainline speeds; presently the MSRPH indicates that “the maximum authorized speed of Class II vehicles is that which is specified by the equipment manufacturer or as specified by OCC, and in all cases shall not exceed 30 MPH”. Finally, while this would also require revision of the MSRPH, equipping work vehicles for ATP should permit them to share the mainline with Class I trains, instead of being restricted (mostly) to non-revenue hours. This could in particular have a real impact in snow removal operations. As I understand the situation now, rather than sending a prime mover out to clear the tracks between revenue trains, WMATA suspends revenue service when snow accumulation reaches the point that it must be removed by a prime mover with a plow. If prime movers could share the tracks with revenue trains, snow-clearing could be made more efficient, potentially keeping the system open longer during winter storms.
Of course, equipping certain work vehicles for ATP doesn’t solve all of the problems. For one thing, there will probably always be unequipped vehicles on the system—whether they’re vehicles not native to the Metrorail system, like an inspection vehicle from Sperry Rail Service, or a vehicle whose ATP equipment has failed. In addition, work vehicles may have to have ATP cut out when operating in areas where the signal system is not operational. But for moving to and from work sites (which may be a long distance), eliminating the need for work vehicles to use absolute block procedures would reduce OCC and train crew workload, increase train speeds, and improve safety. Moreover, equipping work vehicles for ATP is already common practice on other systems where wayside signals have been removed. The London Underground has two lines—the Central Line and the Victoria Line—which do not feature conventional wayside signaling (and the Jubilee Line is being resignaled with Seltrac, meaning it will lose most of its wayside signals at some point). On the Tube, battery-electric locomotives are the principal means of moving work trains, and some of these battery-electric locomotives are indeed equipped for either Victoria Line or Central Line ATP, so that they can operate on those lines. It only seems reasonable to take the same measure on the Metrorail system. It would require a certain amount of custom design and engineering work to equip each prime mover with an ATC receiver, and hardware to apply the brakes if the train exceeds the current speed command, but at the same time, doing so would provide benefits in terms of safety and operational flexibility.
(Final note: WMATA uses the term “prime mover” in a non-standard way; ordinarily the term refers only to the diesel engine or other source of propulsion for a locomotive or similar vehicle, but instead WMATA uses the term to refer to the entire vehicle.)