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16
Apr 00
Sun

Cityrail: Signals

Burgatron reveals the secrets of cityrail signals (thanks mate!). Something I’ve always wondered about… [Post modified to account for early-morning-email-typos]

Well, signal faliures are when the signals stop working, (just like when the traffic lights blank out or stop working). What mostly happens is the signal stays at red (stop) when it should go back to green. Most signals have a trip device on them… if you look down on the ground near a signal you will see a white arm pointing up on a 45 degree angle or just pointing down. When the signal is at stop, the arm should point up (about 45 degrees). Trains have a trip valve connected to the brakes. If a train goes past a red signal, the trip valve hits the white arm, the brakes come on and the train stops. This is so trains can’t just drive round willy nilly without obeying the indication of signals. So, another reason a signal may have failed is that the signal is green but the arm has stayed in the raised position. When the train goes past the green signal, it will trip its brakes, and then the train will have to stop and wait a few mintutes till the air fills its brakes again.

What I want to know now is, what happens when the signals stay at green, when they should be red? Hrm…

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