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| Re: TA is obsessed with CBTC, and ''New'' tech for no reason. (578884) | |||
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Stephen Bauman on Sat Mar 1 12:45:53 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sat Mar 1 11:30:21 2008. However, the existing wayside system with "discrete" trippers permits service levels far in excess of what is currently operated.I don't know that in practice that's true. I have not taken measurements at every station. However, I have taken enough to be extremely confident in that assessment. There are two things you want to measure. The first is the acceleration of a train leaving a station. This is the time interval from when a train starts to move until the signal at the entrance for an incoming train turns green. The second is the braking rate. This is the time interval from when a train passes that green signal at the station entrance until it opens its doors. If the sum of both these time intervals is less than 60 seconds, then 90 second headways (40 tph) with 30 second dwell times are possible. These measurements are designed to test the capability of the signal system. These measurements are taken during off peak hours to insure that train supervision (or lack thereof) does not play a factor. At least on the Canarsie Line, unless there's automatic control of trains operating at higher speeds into and out of the terminals, I gather that we're agreed that while, say, CBTC will leave it theoretically possible to run in excess of 24 tph - I'll trust your numbers for terminal capacity, Yes. I was referring to intermediate station capacity. Terminal capacity is not usually an issue because trunk lines will have branches to different terminals. from what I've been reading on here, possibly the Canarsie terminal wouldn't have permitted 24 tph in capacity, One item on my to-do list is to get out to Canarsie and measure the terminal's capacity. Canarsie's capacity wasn't an issue in the old days because they ran trains to both Canarsie and Lefferts, as well as short turning at both Myrtle and Atlantic. |
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