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| Re: Old LIRR Rockaway Beach Branch (1252585) | |||
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Re: Old LIRR Rockaway Beach Branch |
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Posted by Stephen Bauman on Wed Oct 9 11:56:22 2013, in response to Re: Old LIRR Rockaway Beach Branch, posted by AlM on Wed Oct 9 11:15:40 2013. what you are calling maximum service level is what everyone else is calling capacity.There is an important difference. If economics were not an issue, what would the minimum headway be with the present signal system? What would it be with CBTC? How do these figures compare with capacity? My assertion, based on measurements, is: the current system could handle 90 second headways (40 tph) on both the local and express tracks. They are currently running 30 tph on the express and less than 20 tph on the local. There is plenty of unused capacity available to increase service levels without need (and expense) to change the current signal system. Moreover, the capacity is around 44 tph. There is very little improvement that a different signal system would provide. If their NTT trains had better acceleration and service braking rates to 4.0 mph/sec and the emergency braking rate to 7.0 mph/sec, line capacity would be raised to around 47 tph. It would take a new signal system to realize these capacity gains. CBTC might be a realistic and possibly cost effective option in that case. |
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