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m7zanr160s

Pointless Signals?

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Why are all these new mid-station signals being put in on the QBL when T/Os aren't allowed to pull in until they all clear? In theory, it's cool because it would allow trains to close in on the preceding train, but if they can't, what's the point?

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Why are all these new mid-station signals being put in on the QBL when T/Os aren't allowed to pull in until they all clear? In theory, it's cool because it would allow trains to close in on the preceding train, but if they can't, what's the point?

 

I'm not sure specifically the new signals you're talking about - but even though T/O's can't enter the station until they're clear, timers mid-platform can still help trains get closer together. 

 

Fixed-block signaling requires that a train passing a signal at danger at maximum possible speed, with any semblance of working brakes, be tripped and stop safely before striking the train in front of it. If you've got a 25mph timer mid platform, that means that a train couldn't be going 55 by the time it reached the far end of the platform, and as such, the block in front of that signal can be shorter, and the signals approaching the station can clear faster. 

 

Also, I'm pretty sure trains can still enter the station if the signal aspect is red and lunar white (or one of the other timer aspects for this matter). As long as the signal shows that it will clear if you slow to the proper speed, I think you're able to pull into the station. 

 

I could be wrong on that one, I don't have a rulebook.

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Why are all these new mid-station signals being put in on the QBL when T/Os aren't allowed to pull in until they all clear? In theory, it's cool because it would allow trains to close in on the preceding train, but if they can't, what's the point?

 

Possibly for CBTC. CBTC operation does, when international best practices are followed, allow a train to enter as one is leaving.

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Possibly for CBTC. CBTC operation does, when international best practices are followed, allow a train to enter as one is leaving.

No, with full CBTC the only signals one would see would be interlocking signals. The (L) from B'Way Junction to 8th Av only has interlocking signals.

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One station that has multiple mid-station signals is Lexington Ave.-53 St., which I think were added to what was already there. It would be cool to see trains close in on departing trains, like I've seen on the LIRR at Jamaica Station. Mainly, it would help with efficiency, though.

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^^ That's basically what ST signals do--they allow trains to close in on each other. To see these in action, go to any express station in Midtown or other busy areas during rush hour---trust me. You'll see a lot!

 

-A  :ph34r:

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