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| Re: R Train May Run 8 Cars Instead of 10...Re: Is There an Update on the R160's Wheel Wear Problem? (1640043) | |||
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Re: R Train May Run 8 Cars Instead of 10...Re: Is There an Update on the R160's Wheel Wear Problem? |
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Posted by Stephen Bauman on Sat Mar 15 16:39:39 2025, in response to Re: R Train May Run 8 Cars Instead of 10...Re: Is There an Update on the R160's Wheel Wear Problem?, posted by Train Dude on Sat Mar 15 13:54:10 2025. Williamsburg bridge collision, what did you hear as the major contributing factors?I've discussed the WB collision many times, so I'll skip to the results without the derivation. It's less of what I heard than what I inferred from reading the NTSB report. 1. Obviously, the scenario was initiated by a train operator passing a red signal. However, the signal system is supposed to prevent such an incident from causing a collision. Why didn't it? 2. The emergency brakes were actuated by the train operator passing a red signal. The reason the follower's train did not stop short of a collision was because the emergency brakes applied about half the deceleration of its rated 3.0 mph/sec. The collision occurred on an uphill, so that wheel slippage wasn't a factor. I consider the failure of the emergency brakes to be the major contributing factor. Had following train decelerated at 3.0 mph/sec from the point of its application, the following train would have stopped about 50 feet short of a collision. I consider this to be a maintenance/equipment failure. 3. There are also two design failures that I consider to be contributing factors. If emergency brakes are applied, the primary mission is to stop the train. Throw an anchor overboard, if it would help. :=) 3a. Dynamic braking is not applied during emergency braking. A test was made by applying full service braking (with dynamic braking). The follower stopped approximately 150 feet short of the collision point. Dynamic braking requires both third rail power and operating propulsion motors. Both might not be available during an emergency. Therefore, emergency braking should not depend on dynamic brakes. This does not excuse not applying them. 3b. The trains are not equipped with track brakes. Both dynamic and air brakes require wheels not slip. This limits the maximum deceleration rate. Track brakes work on a different principle - an electromagnet connects the truck to the rail. The electromagnet's static friction stops the train at approximately 6 to 7 mph/sec. The electromagnet's power comes from the battery, so that third rail power is not required for successful application. 4. The MTA's collision explanation was that the newer trains achieved a higher speed than the older equipment. The signal system was designed for the older equipment's slower speed. The MTA's solution was to limit the maximum speed that could be obtained on all trains by altering the throttles. 5. The MTA's CYA response makes me skeptical of any explanation involving rolling stock brake systems. |
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