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| Re: TA is obsessed with CBTC, and ''New'' tech for no reason. (579002) | |||
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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 17:42:54 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sat Mar 1 16:17:51 2008. perhaps NYCT will be using CBTC signals to squeeze more trains through non-terminal stations on the trunk line at irregular intervals, when trains bunch upCBTC might squeeze 5% more trains through non-terminal stations than the present wayside system. That's the limit of its capability. Current maximum service levels are around 66% the capacity of the existing system's capacity. That leaves a lot of squeezing capability for the current system before CBTC's benefits kick in. The train management side would be akin to preventing the drain from becoming overwhelmed in the first place, Do a little thought experiment. How close to schedule does 30 tph operation have to be to avoid bunching (red and yellow signals)? We know the signal system will handle 90 second headways. All we need is a criterion to prevent a 120 second headway from becoming less than 90 seconds. Suppose the leader is running more than 15 seconds late and the follower more than 15 seconds early. The initial 120 second headway is now less than 90 seconds. A sufficient condition, to guarantee that headways do not become less than 30 seconds, is that both the leader and the follower remain within 15 seconds of their schedule at all times. The TA's schedules are drawn up with a precision of 30 seconds. Command, we have a problem! |
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