2006-11-08 09:36:16 · 7 answers · asked by Anonymous in Travel ➔ United Kingdom ➔ London
London Underground trains are controlled by signals, usually green and red, much like traffic lights. If a signal fails it eithers sticks at red, or turns off altogether, both of which are "danger signals" and the driver will stop, as there may be a train ahead.
This obviously causes delays, as trains stop, holding up all the trains behind it, and things have to wait until an engineer can fix it.
It could also mean a points failure, or similar track problem, but customers are told it is a signal failure because its simpler to understand.
2006-11-08 09:43:59 · answer #1 · answered by ashypoo 5 · 0⤊ 0⤋
As Simon r so rightly says, never EVER complain about being delayed by a signal failure, for if the failure were ignored your journey may well be hastened, only in this case upwards!
The signalling circuits work through what are called track circuits, so a signal may only show a green light ("aspect" in railway terms) if certain conditions are fulfilled, some of these being mainly that there is no train immediately ahead, the track is free of any metallic obstruction (i.e. if some prat has chucked an old bike off a bridge at an open section or even a metal drinks can in the wrong place in a tunnel section), any points ahead are correctly set and locked for the passage of the train, and the track itself is not broken. That's all in addition to the actual signal equipment itself - relays, cables etc all being OK, and of course, that the bulb in the signal itself is working. That itself would be comparatively rare for the bulbs used all have double filaments. Hope that's thrown a bit of light on a dark subject..........
2006-11-09 23:28:06 · answer #2 · answered by Dover Soles 6 · 0⤊ 0⤋
The London Underground relies on real drivers looking at real signals controlled by real people.
The last time there was a crash was in the mid 70's when the driver blacked out and missed a signal.
This is the safest public transport system in the world. If a signal fails, and you get home late, tough. That is what happens.
2006-11-08 10:32:11 · answer #3 · answered by simon r 3 · 3⤊ 0⤋
The flow of underground trains is controlled by signals, just like traffic on the roads is controlled by traffic lights. There are junctions on the underground where one train has to wait for another to go past; and there is the need to hold trains while the one in front is still in the station.
If a signal is not working properly, then the trains are disrupted.
2006-11-12 02:08:16 · answer #4 · answered by Bridget F 3 · 0⤊ 0⤋
A signal failure is where the lights (like traffic lights) which tell the trains if it is safe to go or not stop working. If the lights aren't working, it means the trains cannot go past the signal until it is fixed because they don't know if it is safe or not... hence the big delays!
2006-11-08 09:44:25 · answer #5 · answered by Anonymous · 1⤊ 0⤋
A signal has stopped working?
Usually lights I would like to suggest.
2006-11-08 09:38:02 · answer #6 · answered by spiegy2000 6 · 1⤊ 0⤋
emergency pee stop
2006-11-08 09:37:51 · answer #7 · answered by antagonist 5 · 1⤊ 3⤋