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| Re: (interlocking) TA is obsessed with CBTC, and ''New'' tech for no reason. (582560) | |||
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Re: (interlocking) TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by randyo on Fri Mar 7 18:43:58 2008, in response to Re: (interlocking) TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Jeff H. on Wed Mar 5 19:16:16 2008. Certain signals, usually dwarf signals for reverse moves had the screw releases for what the old time Tw/M referred to as "rusty rail" conditions. They never fully explained to me what that meant though. I would assume that the reasoning behind it was that a train operating over an unused portion of track might not properly bridge the track circuit and might allow a false indication of a clear track circuit over a switch thus enabling it to be thrown with a train still present. By requiring the lengthy process of cranking the signal back, the likelihood of being able to throw a switch with a train still on the circuit would be greatly diminished. I do recall when I was a M/M on the West End Line, I had a rail polisher trick on Mondays on which I and the drill M/M from Bay Pky would operate over all the unused switches at Bay Pky and 62 St and operate over the middle track from 9 Av to Bay Pky. On Mondays after a heavy rain storm, the rails would be so rusty that the wheels would not properly bridge the track circuits and when they did they did so intermittently. As a result, automatic signals on the middle track would often come up under the train and trip it. The Tw/M would receive an indication on the model board of a train "disappearing" as the track circuit cleared briefly. You can see if that happened over a switch citcuit, it had the potential to give a false clear indication allowing a switch to be thrown unless the ability to do so was delayed in some way. |
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