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| Re: The Washington Metro's 26 TPH limit (1406078) | |||
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Re: The Washington Metro's 26 TPH limit |
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Posted by fdtutf on Tue Aug 23 10:19:36 2016, in response to Re: The Washington Metro's 26 TPH limit, posted by Sand Box John on Tue Aug 23 00:15:26 2016. I quote from the post I linked to:This limit was put to the test in 2000 where, in response to the “Orange Crush”, Metro scheduled 29 trains per hour (19 Orange, 10 Blue) through the Rosslyn portal. However the aggressive 29 trains per hour (125 second headways) schedule was rarely achieved even with a mix of shorter 4- and 6-car trains, which tend to favor close headway operation. This was primarily due to tight operating margins and unattainable dwell times, scheduled at 12 seconds outside, and 19-23 seconds inside the core (far lower than the study’s recommended 40 seconds). What's your analysis of this, John? What I'm thinking is that if they were using a mix of 4- and 6-car trains for this, assuming this was rush hour operation, 4-car trains are just a bad idea because they're not going to be able to absorb the crowds, and people trying to board at the ends of the train (in 2000, WMATA trains would have still been stopping at the proper platform positions) would lengthen dwell times. Actually, this tends to support your contention about rolling stock shortages being a, if not the, major reason why WMATA can't achieve tighter headways. I do still believe, though, that the idiotic door arrangement extends dwell times significantly. |
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