Metrolink peer review report - Ventura County Star

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METROLINK COMMUTER RAIL SAFETY PEER REVIEW PANEL Final Report – January 5, 2009 The violation immediately preceding a collision can result from one or more of several failures: Issue Papers • A movement authority may have been issued in error (by miscommunication or misunderstanding of train orders); • A train operator may have missed a wayside signal set at a stop, or mistakenly acknowledged an ATS warning without taking the action required for safety; • The operator may have exceeded authorized train speed by inattention or improper handling of the train; • A mechanical failure of the signal or mechanical failure of the vehicle braking system may have occurred, or train lading may have become unsecured resulting in a side-swipe; • Track integrity may be lost such as by a broken rail, misaligned track, a wash-out, or heavy obstruction. Of the failures causing train collisions, the largest group is human error – predominantly “signal passed at danger” (SPAD) and overspeed incidents. Failures of properly installed signal equipment, by comparison, are quite rare (See Chart 3). There is a long history of train wrecks on railroads around the world, many of them catastrophic. Federal Railroad safety regulations are aimed at reducing the frequency and consequences of train wrecks, with measurable effect. ATS, for example, dates back to the 1920s. Railroads and their suppliers have worked for the last two decades to develop more advanced communications-based positive train separation systems. These systems would be designed to prevent train collisions such as the ones at Hinkley, Alberta in 1986, which killed 23, Kensington, Maryland in 1996 (11 lives lost), and many others. The National Transportation Safety Board has had development of advanced positive train separation systems on its “Ten Most Wanted” list since its inception in 1990. Automatic Train Stop (ATS) Automatic Train Stop is a control technology dating back to the 1920’s. It works by making an electrical interconnection between a controlled track segment, the signal system governing train movement, a train occupancy detector (such as induction coils in the track) and the train’s air brakes. With an “active” ATS system tied into wayside signals, if a signal indication were set at restricted speed but a train passed over a detector in that segment, the system would issue a warning (typically through an alerter installed in the locomotive cab); if the locomotive engineer fails to acknowledge the restriction within a pre-set period of time, the train’s emergency brakes would be set. ATS transponders are typically installed at Control Points and at risky locations based on track speed and signal visibility conditions. There are several problems with an ATS system of this kind. The design is reactive; Signal Passed at Danger (SPAD) cannot be anticipated – the locomotive can only be controlled after the fact. An ATS system does not protect against a reflexive acknowledgement by the engineer. With ATS, once the engineer acknowledges a change in signal indication, he or she can continue to operate the train without restriction. It neither assures a positive stop before the end of movement authority or at the signal location nor requires the engineer to reduce train speed with a restricted signal indication greater than a stop. ATS protects for following moves but does not protect for meets or conflicting movements. Enforcement of an unacknowledged warning occurs only after a delay, and then with an emergency brake application that in a freight train can itself cause a derailment – rather than a more graceful service braking application to bring the train to a 52
METROLINK COMMUTER RAIL SAFETY PEER REVIEW PANEL Final Report – January 5, 2009 Issue Papers safe stop. Use of cab signals is usually indicated, in two particular circumstances – cab signals or the equivalent is required for operation above 79 mph and may be deployed where fog frequently obscures wayside signals. ATS might be considered to cost less than other solutions, but only if the circumstances fit its limited functionality; every train using the line must be equipped, but not every collision can be prevented. Passive (or “inert”) transponders cost about $20 thousand each, but the more effective active transponders (only active when the signal system indicates restrictive speed) run about $160 thousand per location. ATS technology is dated, and ATS equipment (even active transponders) can not be deemed as a precursor to PTC. The ATS equipment would be discarded as part of the PTC installation. SCRRA has applied to the FRA for a waiver to expand ATS beyond its current ATS territory. Currently the Metrolink system uses a passive/inert ATS on the Orange County Line south of Anaheim, which is the same system used on the San Diego Coaster commuter rail system. This ATS system uses passive/inert inductors which are not tied to the signal system. SCRRA plans to expand the use of ATS outside the Orange Line territory by installing 43 passive/inert inductors at spots where there is a 20mph or greater speed restriction. As noted above, ATS will only prevent or reduce the potential impact of accidents. Therefore, the expansion of the ATS technology on the Metrolink system should be limited to those areas of the right-of-way that provide the greatest potential for reducing the risk of accidents. In summary, • ATS technology is dated, and ATS equipment (even active transponders) does not migrate efficiently to the more advanced Positive Train Control technology. ATS will have to be discarded when implementing PTC; • ATS is a reactive system and doesn’t positively stop a train; the locomotive can only be controlled after the fact; • An ATS system does not protect against a reflexive acknowledgement of a signal by the engineer; in that case, the engineer could continue to proceed at speed past a signal or restriction and potentially collide with an oncoming train; and • The expansion of ATS on the Metrolink System could divert both financial and engineering resources that could be better spent on installing PTC. Positive Train Control (PTC) PTC is the most widely used name for advanced communications-based train control systems designed to prevent train-to-train collisions, overspeed derailments by controlling speeds at designated civil restricted track locations, and provide protection for track maintenance forces working in their assigned track location. (Track forces can only be protected from a moving train if they, like a train, have a unique authority for track occupancy within specified work limits, and if the principle of ensuring only one occupant per track segment at a time is strictly observed.) PTC designs are integrated systems using various components to determine precisely where the train is located, what track occupancy and movement authority it has been given, how the engineer is handling the train’s operation with respect to that authority, and (if the train’s authority is likely to be violated) how to bring it to a safe stop. These functions could perhaps be refined to the point where, out on the main line, no operator would be needed at all (auto pilot). Railroad managers do not propose to extend PTC that far; the preferred concept of operation is to guide and remind the engineer, leave safe operation in his/her hands, and intervene only to prevent imminent violations of movement authority and speed limits. 53
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Metrolink peer review report - Ventura County Star

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