Joe wrote:
I was on a 165 formed of 3 x 2 carriage sets the other day, sat at the
front of the back 2 car unit. The driver passed the signal and by the
time my coach got to the signal, (as you'd expect) it had a red aspect
showing, but why wasn't the train 'tripped?' Do all the tripcocks
become inactive apart from the ones in the 1st unit when they're
coupled together, or do the train stops raise after a delay (say
30Secs) or so to allow the train to pass over?

Tripcocks in the middle and at the rear of the train are rendered
inoperative, i.e. only the one at the front is working.

Where I live (Sydney, Australia) we use a similar trip system in the
Suburban area.

The all but the front trip have to be retracted manually. Only the latest
model trains have trips that are remotely raise-able.
When a train is coupled, it's part of the job to retract the now middle
two trip arms. A small lever is provided and the arm locks up.
Part of a drivers job when 'preping' a train is to make sure the front
and rear trips are infact lowered.

This way, no trip arm ever hits anything at speed.

The other method, which I believe the New York subway uses is to
'suppress' the trip arm, it lowers as the train passes the signal. At
least one accident was attributes to this system as drives could edge past
a signal at stop and not get tripped - which involves reseting the trip
cock.


Thus a trip cock arm never hits a trip arm at speed, unless it's the
leading one and the train is a SPAD.