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| Re: MTA's Half Minute Concept (1436941) | |||
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Re: MTA's Half Minute Concept |
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Posted by Stephen Bauman on Mon May 22 13:00:25 2017, in response to Re: MTA's Half Minute Concept, posted by Fine, Howard, and Fine on Mon May 22 09:47:20 2017. Half minute precision in planning is important especially for managing merges and express/nonexpress interleaves.It's utterly inadequate. It takes approximately 1 minute (60 seconds) for a train to enter and clear an interlocking. Suppose trains are scheduled to arrive at the merge every 2 minutes (30 tph). If leader and follower are within 30 seconds of their scheduled arrival, then the follower will not be delayed. Leader and follower must be within 15 seconds of schedule, to guarantee no delays for 90 second headways(40 tph). Clearly, keeping track of schedules to a 30 second precision is as useful as using a sundial in the subway. Systems that operate around 40 tph, measure station arrival/departure times in seconds. Their crews are expected to maintain such schedules because there is a departure clock at each station that measures time in seconds. |
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