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| Re: The F report (842459) | |||
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Re: The F report |
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Posted by trainsarefun on Sat Oct 10 11:51:10 2009, in response to Re: The F report, posted by G1Ravage on Sat Oct 10 01:53:34 2009. The relay doesn't negatively impact service. If the train arrives late, it can be double-ended for a quick relay.To be more specific than I was originally, let's grant that the train arrives on the Jamaica-bound trip ON TIME (as opposed to merely being 'on time' for statistical purposes). But the train then emerges on D3 as a Coney Island-bound train 2-4 minutes behind scheduled departure time. Another minute or so tacked on to receive passengers then. Then coming into 169 St, the train slows to switch over to the local track. Then coming into Van Wyck Blvd, there is another slow-go, especially if an E train crosses ahead of our F train on to the local track: time to clear = E train switching time + E train dwell time (longer for R160s) + switch reset time (which probably overlaps somewhat with signal clear time) + F train dwell time (longer for R160s). By this point, if Van Wyck Blvd were the southern terminal, the F train is no longer on time, even with the cushion factor. At 75 Av, the F train crosses back over to the express track. Then into 36 St, for whatever odd reasons on too many trains, the signal is at red over red for 30-60 seconds even though the punch was at Roosevelt Av and there are no switches in between. The odds of our F train reaching 42 St on time are thus quite slim off-peak. And this is without track chip out, flagging, slow orders, and the like. If the train is *that* late, the interval will be ABD'd anyway. Sure but *that* can't possibly help schedule reliability: one train does the work of two. The problem is the length of the line, the number of merges with other lines, and the fact the line is very crowded due to serving popular neighborhoods. It's easy to lose your time on this line, and not get it back. If the trains are too crowded off-peak (the report suggests shoulders of the peak as culprits), one solution is to add more trains, which although costly in terms of labor, has the effect of creating two on-time trains in the place of one delayed train. If trains keep to tighter windows of when they are supposed to be at the interlockings, the merges can be scheduled so as not to conflict, the big merge being with the E running at an equivalent frequency of service. But with trains scheduled to run at combined 2-4 minute headways running 2-4 minutes behind schedule, it's a prescription for congestion. |
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