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| Re: Water St Subway instead of FTC and SF rebuild? (was:Re: Would 4-track express service...) (487102) | |||
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Re: Water St Subway instead of FTC and SF rebuild? (was:Re: Would 4-track express service...) |
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Posted by Stephen Bauman on Fri Sep 7 09:03:34 2007, in response to Re: Water St Subway instead of FTC and SF rebuild? (was:Re: Would 4-track express service...), posted by (SIR) North Shore Line on Thu Sep 6 20:24:52 2007. during the height of the PM Rush Hour, there was almost always three trains below Rector St at any given time.That's pretty good. The distance between the Rector station and South Ferry is approximately 2000 feet - measure it on Google Earth. Each train occupies approximately 800 feet: 510 feet for the train itself and 300 feet as a buffer between the trip arm and the back of the train in front. That means that those 3 trains below Rector need at least 2400 feet of track. One reason for backups at terminals is a result of the TA's "improved" on-time performance. One of the TA's strategies to "improve" on-time performance was to increase the scheduled running times. The running time from 242nd to South Ferry used to be 49 minutes; currently it's 55 minutes. The majority of trains did not need the extra 6 minutes, even when on-time performance was an abysmal 66%. They would arrive at their terminals substantially early. Trains were not released from terminals early. The result was that all the pockets at the terminal were probably filled up for two-thirds of arriving trains at terminals. The result was instant backup. How long a backup? The recovery time at the terminal is 3 minutes plus the additional off book recovery time of 6 minutes from the inflated schedule for a total of 9 minutes. Service levels are 20 tph for 3 minute headways. So, 9/3 = 3 for 3 trains in limbo. H'mmm..... |
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