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| Re: SAS termini questions (126630) | |||
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Re: SAS termini questions |
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Posted by Stephen Bauman on Sun Aug 14 07:23:54 2005, in response to Re: SAS termini questions, posted by stephenk on Sun Aug 14 06:38:10 2005. But is the Lex's reversing capacity is its major contraint?Hardly. The Lex has a reversing terminal that handles only 2 trains during the am rush hour (South Ferry). The Brooklyn terminals (Flatbush and Utica) plus Rogers Jct limit additional express service. There are some routing changes that could increase express service in Brooklyn. I would have thought that excessive station dwell time would be its capacity limiter? It's pretty difficult to evaluate station dwell time on the Lex because service is so irregular. However, the theory is a no brainer. The amount of dwell time is related to the number of people trying to cross the door threshold. The more people the greater the dwell time; fewer people then less dwell time. The total number of people crossing the door threshold during the entire rush hour is relatively constant with respect to the number of trains. However, the number of people crossing the door threshold for each individual train is related to the number of trains. Want to decrease dwell time? Add more trains. Track geometry does limit the Lex express capacity to slightly less than 40 tph. The problem is the express-local junction south of 125th St. They might be able to fix it by redesigning the signals. However, there's no rush because that junction limits the tph to the high 30's and they are currenly operating only 26 tph. The TA's principal impediment to increasing rush hour service levels is cost. In order to increase service during the 2 hour long rush hour period, the TA must pay an additional 16 man-hours for each train added. Each additional train for both the am and pm rush hours costs an additional 32 man-hours. The cost of increasing rush hour services levels by 20% (to previously operated levels) is just too high. |
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