|Re: Village Voice Article Explains: The Trains Are Slower Because They Slowed the Trains Down (1469460)|
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Re: Village Voice Article Explains: The Trains Are Slower Because They Slowed the Trains Down
Posted by Stephen Bauman on Tue Mar 13 17:21:19 2018, in response to Re: Village Voice Article Explains: The Trains Are Slower Because They Slowed the Trains Down, posted by randyo on Tue Mar 13 16:26:09 2018.The Willy B accident was a result of the signal system that was there at the time being the original one that was designed for shorter trains of el cars and never upgraded for the longer trains of steel subway cars that eventually operated there. wit signals properly spaced for the maximum length of trains operated on a line or division, trains wouldn’t have to be artificially overslowed down.
The NTSB ran tests with similar equipment on the Williamsburg Bridge. The the tests showed: the train hit the tripper at 34 mph and the emergency braking rate was 1.8 mph/sec. The train was supposed to have an emergency braking rate of 3.0 mph/sec. The BU gate cars were supposed to have an emergency braking rate of 2.0 mph/sec.
NYCT's CYA excuse was that the newer trains were too fast for the old signal system. Their "proof" was that the designed maximum attainable speed (MAS) was supposed to be 28 mph when the tripper was hit, not the 34 mph recorded by the NTSB. Going through the high school physics calculations, the train would have stopped 44.6 feet short of the collision point with the existing brakes.
NYCT conveniently did not mention that had the emergency brakes performed as per the 3.0 mph/sec spec, the train would have stopped 48.5 feet short of the collision point.
The NTSB also ran a test where full service, rather than emergency, braking was applied at the tripper point. The train stopped 126 feet short of the collision point.
Having successfully dodged the gross negligence bullet, NYCT had to live with its consequences. One of the NTSB's recommendations was to include speed control on all signals. This is the policy NYCT is following. This would not be a problem, if the speed control were set to the 3.0 mph/sec emergency braking specification. It would also not be a problem, if the T/O's were not super cautious and go even slower than the nominal timed speed rating. However, the speeds were probably set too low and possibly would trip a train if it were going at the the stated control speed.
Another NTSB recommendation was to apply the dynamic brakes, in addition to the air brakes, in an emergency. This could have been implemented on the NTT trains, which have a different truck design. It hasn't.
the signal system that was there at the time being the original one that was designed for shorter trains of el cars and never upgraded for the longer trains of steel subway cars
As an unindicted co-conspirator used to say, "let's make this perfectly clear."
Collision occur between the last car of the leader an the first car of the follower. How many cars are ahead of the leader's last car or how many cars are behind the follower's first car don't count.