Great Western Coffee Shop

Hi
Sorry if this is in the wrong area, just got a question i'm hoping someone out there in web land would be able to help me with...
I was on my way upto Cheltenham this morning, and we stopped a bit down from the Gloucester junction.
i look back out the window when we start moving, and see that theres no track, when theres suppose to be track...we're going up the down track. we move back onto the right track at the gloucester junction.

i ask the TM as we're pulling into Cheltenham, and he says it was because of a... i think he said Track circuit failer???

I might of heard him wrong, i might be talking a load of nonesense..
But can someone please shed some light on if i got that right, and what it is/means in laymans terms, please?

Track circuits are the way the signalling systems detect trains. A failure = signals don't work. But I'm surprised you ran wrong line rather than the driver be advised to procede at caution and to maintain stopping distance within sight. Maybe that section is reversibly worked, but I wasn't aware it is.

There is 'some' reversible between Tuffley and Gloucester Yard, unusual to use it though as trains usually cautioned over affected section for track circuit failure as John R says

It's possible that whilst it was TC failure, TC failure can be because of a broken Rail.

i doubt they could proceed at caution as the original poster says the track was not there!

I think he meant that he had switched to the wrong line. I don't think it had vapourised.

probably a cracked rail then

It's possible that whilst it was TC failure, TC failure can be because of a broken Rail.
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Agreed but unless positively identified as such, trains will still be cautioned over the affected section until the S&T arrive.  Even then, providing the break meets certain criteria (which the rapid response staff should be trained to identify) trains are allowed to pass over at walking pace.  Obviously if no trained staff are available then everything stops until the P Way can clamp the rail and impose a speed restriction.

*smiles* sorry, bad sense of humour on my part, i did mean that we'd swapped sides on the tracks, not that it had dissapeared.

They do still work to a certain extent. They fail safe thus turning to show a red aspect.ie if a track failure occurs or say a green light blows a filament the red light comes on. Now I hear you say "what if a red light blows a filament then" Well these have bulbs with three filaments and are checked by the S&T department on a regular basis and changed if all three aint working. If a red light does on the rare occasion go completely blank then the preceding signal will also fail safe and go red. If however a driver comes across a signal showing no aspect then the rules says the train should be stopped ASAP if not sooner and the signaller consulted!

  ::)

The bulbs used in conventional colour light signals have TWO filaments.  A main filament blowing will automatically cause the auxilliary  filament to light and give an indication back to the relay room/signalbox that there is a problem that needs to be attended to by the technicians. However the trains keep running.  If the second filament subsequently blows then the signal in rear will be held at danger (red) as you correctly state.  Even if the signal was correctly displaying a proceed  aspect and both filaments failed, the signal in rear would revert to red. 

Sorry, I didn't mean that the signal itself failed to work. I should have been more accurate and said that the failure of the track circuit caused the signals to default to danger.   

The Rulebook is quite clear when a Signal fails to show an aspect it is taken as REDshowing danger.

Say signalandtelgraph am I right in the days of oil lamps and semaphore signals because the flame of the lamp burnt yellow the glass lens was BLUE in the off aspect as Yellow plus Blue makes Green?

Looks more blue than green when you see it in daylight so your theory may be true. 

Thanks Mr (or Miss) S & T.

Mr (for the record!)

I'm happy to up Grade you to LORD!