In article .com,
TheOneKEA writes
Why? If one red signal can protect the obstruction, what's the need
for more?
You just showed that under certain circumstances, one signal is not
enough to protect an obstruction (or at least I think you did...)

Um, no.

You have to make *some* assumptions when designing a signalling system.
The ones LU make a
(1) train stops will stop trains in the design distance;
(2) trains won't be exceeding the speed limit at the point they pass a
red signal in the worst situation.

Within those assumptions, one signal is all that's needed. There may be
two or more, but only one is doing the protecting.

--
Clive D.W. Feather | Home:
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