Banner Repeaters and Locations

[Crossover]

Quickish question, just based on something I was discussing with a fellow passenger whilst stood freezing on Grantham station last Monday during the ECML disruption, which I thought I'd ask the question here.

Is there any reason why, in some cases, a signal couldn't be located back towards where the banner repeater, removing the need for one?

This came about whilst stood on Grantham platform 2 where the signal on the Down line is round a curve and there is a banner repeater by the end of the platform. Thus, a non stop EC HST (grrrrr!!!!) came through and stopped with the back end still on the platform.

Logic would suggest the signal may be better placed as a starter at the platform, rather than metres after it. My thoughts may be to do with a junction location or to do with signalling block lengths (the signal in rear at this location is just before the platform, as the next EC 91 non stopper had stopped at the one in the rear (not at the same time as the HST was in front, I hasten to add) so the signaller could talk with the driver) which was my first thought when speaking to one of my fellow passengers about it.

I'm thinking more generically as reasons would differ from site to site but the Grantham example illustrates what I mean fairly well I think.

Any thoughts?

 

[rmt-driver]

There used to be a old fashioned mechanical Banner signal built into the platform canopy on the down at Kew Gardens, It was really rather lovely. Was for the LUL and LOROL drivers to see what the starter was as they arrived into the platform (could be seen from quite a distance whilst the starter was last minute visual). Such a shame it was replaced by the regular 'digital' version recently!

 

[The Planner]

You would be shortening the block section and possibly making it under-braked, therefore you would either have to lower the line speed or place some sort of controls prior to that signal such as fixed double yellows. You will also potentially affect the headway as well as you are lengthening the next section.

 

[Welshman]

Back in the days when Adam was a lad, the down starter at Grantham used to be nearer the end of the platform, and it also controlled the junction with the Nottingham line.

Then that junction was moved to the southern end of the station, the curved track at the north canted for higher speeds, and as The Planner has said, higher line speeds need greater distances between signals for braking purposes.

So the signal was moved further north, where, incidentally, it now also controls the convergence of the returning loop line through platform 4 to the down main, but as it is now towards the end of the curve, a repeater is provided, which can be seen from the platform.

Incidentally, the repeater has only been in situ from fairly recently - until then, trains receiving a yellow at the previous signal had to trundle slowly through Grantham until the next signal was sighted, so it's a good use of a repeater to enable speeds to be increased.

 

[matchmaker]

At Stirling the up Perth line home was moved further back along the platform and changed to a LED head from a semaphore. A banner repeater was also provided as the platform curves and the new location of the home made it less visible to an approaching driver (sounds daft, but true). The signal was moved, AFAIK, to allow an up train to stand at the signal when the road was set for an Alloa line train.

The old location of the signal meant that the junction was within its fouling point, and up trains could not have been accepted by Stirling Middle from Stirling North if there was a move on or off the Alloa line.

 

[Daniel]

Just for interest, there are still proper (rotating) banner repeaters on LUL in the area of Rickmansworth (JP) box.

 

[Cherry_Picker]

Indeed there are, and they are bloody horrible things compared to the LED ones on the rest of the network. Cant see them going any time soon, the linespeed on the up through Rickmansworth is quite low (50 on the approach falling to 25 through the station) that you do get quite a lot of time to see the signals, but the one outside the station can be a pain to see at night from a distance. It just appears to be a white powder coated disc with a black stripe on it and it is illuminated by a weak lamp. I'd at least like to see retro reflective discs there.

 

[142094]

Sure there is an old style one at Dundee as well.