Rail gap indicator

Many thanks. Good read as well at the link.

Including the east end of the westbound at Barking.

Ok then. Where are there RGI telephones?

So if these are only illuminated if the current is off, surely they are not fail safe?
Also, if you pass one, is it counted as a SPAD?

The main thing that you must remember is that rail gap indicators are what their name suggests an 'indicator'. They should never be trusted as positive proof that the current is off or will stay off. Secondary means should always be employed.
Obviously, like any red light, it is a warning to the T/O to stop but, because it can come on at any time, there are special regulations on what to do if you are in a situation where you cannot pull up in time (as has been mentioned).
The matter of whether it is fail-safe is apparently complex as a rail gap indicator serves several purposes. If the sequence was reversed to show a light only when there was current on the track, there is the danger that a bulb failure would give an indication that current had been discharged. The present arrangement of using lights to indicate that the current is off means that a bulb failure suggests that the track is live - so in this respect it has what might be termed a reverse fail-safe mechanism.
Of course, if the bulbs fail and a train passes onto a dead section without knowing, then there is a danger that the section ahead could become live, but that would be no different to the current being discharged the moment after the leading cab passes the indicator. I am sure that T/Os will confirm that they would always try to avoid stopping on a rail gap - even if the current appeared to be on. In addition, if a T/O needs to discharge current, that operator will take measures to protect their train and their passengers in case the gap into their section is bridged.




_{Edit to highlight text}

If the Rail Gap Indicator is illuminated, it may mean (it may be defective or apply for one, not all routes) that Traction Current Ahead is Off. It should never be used to find out that Traction Current is OFF.

Train Operators and Drivers should stop their train before the RGI, if this is not possible then they should coast fully into the section.
They should then contact the Service Controller, who will find out why Traction Current is off (if they don't already know) and await further information.

If it is defective as shown, they it would be reported to the Infraco and Power Control. It would most likely be "bagged over" until it is fixed. Power Control would also be told that if they need to discharge the defective section, they they must also discharge the section to the rear.

Passing an RGI would not be treated as a SPAD, but ignoring it would be treated as a seroiously as one.

-Now tries to see what I have missed out ;-)

I've heard stories of Drivers being done for a SPAD for passing an RGI when lit when sufficient sighting/ stopping time was given.

Track walkers during engineering hours will sometimes refer to them as cherries.

And at Earl's Court Picc just off the platforms!

Also, if the RGI is defective, the controller should make arrangements that if traction current is discharged in that section, the previous section would also be discharged - this should prevent a train from bridging the gap.

Yes quite correct. I have to say those new TEDs seemed to be less useful than the originals. At Earls Court they seemed to less than 100%. My understanding is that they were designed by an ex-Shift Supply Engineer and of course responsibility for TEDs thus passed from signals maintenance to Seeboard/Powerlink, EDF Energy or whatever they are called these days.
I'm not quite sure when the new TEDs were introduced but I had some involvement in TEDs in the late 1980s and early 1990s. I designed and built the original HQ TED panel for the NCC and before that I was involved in the splitting of the infamous Section 1 (which once covered Bakers Street to Amersham, Chesham, Watford, Uxbridge and Stanmore) into new sections 1, 37 and 38.

As far as I know all the TED kit for the old system was still extant and connected at trackside, sections 8,9 and 34 were on my maintenance patch.

Unless it was a fault with the RGI it sounds like the current was off on the westbound traction current section.

No wrong'uns lowered at Ealing at all this week?

Not for me, although the signaller(s) kindly provided my trainee with the experience of one at High St Ken (platform 2 for a reversing train - sadly they didn't tell us to go ahead and take it!) and the route from Earls Ct to Gloucester Rd when we were supposed to stable at triangle.

I didn't think it was that unusual for them to be referred to as cherries. Certainly a term I have been familiar with for a long time.