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| Re: Future expansion wish list? (878627) | |||
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Re: Future expansion wish list? |
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Posted by trainsarefun on Sat Dec 26 23:31:00 2009, in response to Re: Future expansion wish list?, posted by AEM-7AC #901 on Sat Dec 26 21:35:51 2009. Sorry if I mislead by not making scope clear, but my comment was directed at non-relay terminals, specifically, the stub-ends (Main St), or the stupid-switched (Jamaica Center).Anyhow, as to your comments - how much more can be squeezed out of the Queens Railway if we improve the terminal design? The trackage itself is good for 30-40 tph based on signal clearing time. Passenger fumigation can be dealt with a number of ways, as you recognize, i.e., "Isn't the easiest way around this is for crews to have both crews on the train when the run ends on the Northbound platform in lieu of having the T/O walk from one end to another?" It's labor-intensive, but several orders of magnitude cheaper than drilling a new line. Another problem is that since we have merges, those have to be scheduled carefully. Here, Jamaica Center comes up as a rate-limiting step and then WTC as the next rate-limiting step. I don't intend to solve the equations myself now, but to make it simple, one would aim for a 1:1 ratio at the merge points, given the service requirements. But then WTC can't handle more than, I would estimate, 16-24 tph, even if you cheat at the north end by using 179 St to get around the impractical switch placement between Sutphin Blvd and Jamaica Center. So that would put practical express track capacity at 32 tph, conservatively. Operationally, it would also require that the merges occur on time, and by that I don't mean what passes for 'on time' in MTA's performance measures. For similar reasons, peg the local track the same, which gives 64 peak tph on two tracks. With more efficient terminals, this could theoretically be pushed up to near 80 tph on two tracks, or more than a train per minute, which is more than enough to meet needs for many many years to come. |
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