Signalling and tunnels

[Silver_Link]

Hi all,

 

This is going to sound like a daft question but here goes;

 

If there is a tunnel between a signal box and a distant semaphore signal, would the distant signal be fixed?  If not and it is operational how would the wiring, used to control said signal run through the tunnel? Would it be in the cess of the tunnel floor or would it run along the walls in tubing?

 

I'm looking at NER territory, probably somewhere around the southern or lower central regions between 1900 and 1920.

 

Many thanks again

 

Karl 

[uax6]

Why would the distant be fixed because of a tunnel?  There are reasons why it would be fixed, but just because there is a tunnel is not one of them.

The wire run would normally be as per a platform face, pulleys cleated into the brickwork (with provision around recesses so the P-way don't fall over them). The distant could of, course be motor worked, so just a pair of wires in the cablework through the tunnel. 

 

Andy G

[Jeremy Cumberland]

I suppose there would need to be a repeater in the signal box, so there would be an electrical cable as well.

[Silver_Link]

3 minutes ago, uax6 said:

Why would the distant be fixed because of a tunnel?  There are reasons why it would be fixed, but just because there is a tunnel is not one of them.

The wire run would normally be as per a platform face, pulleys cleated into the brickwork (with provision around recesses so the P-way don't fall over them). The distant could of, course be motor worked, so just a pair of wires in the cablework through the tunnel. 

 

Andy G

Thanks Andy.  I thought that it may have been fixed to warn or caution as there may be limited visibility of the home signal on leaving the tunnel.

 

Now that you have mentioned platform faces it's obvious.

 

Thanks

 

Karl

[The Stationmaster]

18 hours ago, Silver_Link said:

Thanks Andy.  I thought that it may have been fixed to warn or caution as there may be limited visibility of the home signal on leaving the tunnel.

 

Now that you have mentioned platform faces it's obvious.

 

Thanks

 

Karl

Think of it thos way Karl.  If it is a worked Distant and it is standing at caution the Driver of anapproaching train will be looking out expecting to find the Home Signal at danger.  If it is a worked distant and it is at clear the Driver will expet to find the Home Signal at clear.

 

Now translate that to a Fixed Distant which is always at caution - so doesn't give a clue about the state of the Home Signal so in theory the Driver doesn't know what to expect, so in theory he expects t find the. Home Signal at danger.  But in reality he might well work on the basis that we don't usually get checked here  - so doesn't bother too much about the Home Signal - until he sees it at danger!  Basically a fixed distant does little beyond reminding a Driver where he is and that he is approaching a stop signal.

 

The GWR did things rather differently with Distant Signals because it fixed them at caution, other than at junctions, if there was a restriction of speed to 15 mph or less in Station Limits between the stop signals to which it applied.  Hence on single lines on the GWR distant signals at crossing places were normally fixed at caution because the speed for hand exchange of tokens was restricted to 10 mph

[Silver_Link]

Hi Mike,

 

Thank you for the explanation.  It makes more sense now.  I suppose that because it would be a double tracked branch, no tokens would be exchanged so exchanges wouldn't be a concern.  If the signalman needed to speak to the driver it would then be a case of putting the distant at caution and home at danger, which would then inform the driver of a potential issue, whereas under 'normal' conditions both would be off. 

 

I think because I have no experience of working distant semaphores (I worked for a heritage line where all distants were fixed), the actual reason of operation passed me by.

 

Thanks again 

 

Karl

[Jeremy Cumberland]

39 minutes ago, Silver_Link said:

If the signalman needed to speak to the driver it would then be a case of putting the distant at caution and home at danger, which would then inform the driver of a potential issue, whereas under 'normal' conditions both would be off. 

Under "normal" conditions, both are on. If the signaller is able to pull off all the stop signals for a train, they will also pull off the distant (if a worked distant is provided), allowing the train to pass through the station without slowing down. Returning signals to danger in front of an approaching train is only done in an emergency.

 

If any of the stop signals need to be held at danger (perhaps, for example, the signaller doesn't have line clear for the next section, so the starter cannot be cleared), then all the stop signals will be held at danger until the train is within sight of them, and of course the distant will be at caution. The train will be cautioned at each stop signal in turn (brought almost to a stand, as the rule book has it) up to the one it needs to stop at. This in turn means that if the driver passes the distant signal at caution and subsequently sees the home signal at clear (without being cautioned at it), they will know that all subsequent signals controlled by the same box are also clear, and so they can accelerate.

Edited January 7 by Jeremy Cumberland

[Silver_Link]

20 minutes ago, Jeremy Cumberland said:

Under "normal" conditions, both are on. If the signaller is able to pull off all the stop signals for a train, they will also pull off the distant (if a worked distant is provided), allowing the train to pass through the station at line speed. Returning signals to danger in front of an approaching train is only done in an emergency.

 

If any of the stop signals need to be held at danger (perhaps, for example, the signaller doesn't have line clear for the next section, so the starter cannot be cleared), then all the stop signals will be held at danger until the train is within sight of them, and of course the distant will be at caution. The train will be cautioned at each stop signal in turn (brought almost to a stand, as the rule book has it) up to the one it needs to stop at. This in turn means that if the driver passes the distant signal at caution and subsequently sees the home signal at clear (without being cautioned at it), they will know that all subsequent signals controlled by the same box are also clear, and so they can accelerate.

Hi Jeremy,

 

Sorry yes.  I do know that signals are usually kept at caution/danger. I should have elaborated more and said that when a train approaches and if the next section is clear then the signal would be off.  This is what I meant by 'normal' but I should have chosen my words better.

 

Thanks

 

Karl 

[Michael Hodgson]

2 hours ago, The Stationmaster said:

 Basically a fixed distant does little beyond reminding a Driver where he is and that he is approaching a stop signal.

 

If it has an AWS ramp associated with it, that should help him wake up.

[The Stationmaster]

2 hours ago, Michael Hodgson said:

If it has an AWS ramp associated with it, that should help him wake up.

Should being the operative word - a succession of double yellows and the Driver might well have got into 'auto AWS cancel mode' (although that  shouldn;'t be the case at a distant signal)

[SM42]

On 07/01/2024 at 18:34, Jeremy Cumberland said:

Under "normal" conditions, both are on. If the signaller is able to pull off all the stop signals for a train, they will also pull off the distant (if a worked distant is provided), allowing the train to pass through the station without slowing down. Returning signals to danger in front of an approaching train is only done in an emergency.

 

If any of the stop signals need to be held at danger (perhaps, for example, the signaller doesn't have line clear for the next section, so the starter cannot be cleared), then all the stop signals will be held at danger until the train is within sight of them, and of course the distant will be at caution. The train will be cautioned at each stop signal in turn (brought almost to a stand, as the rule book has it) up to the one it needs to stop at. This in turn means that if the driver passes the distant signal at caution and subsequently sees the home signal at clear (without being cautioned at it), they will know that all subsequent signals controlled by the same box are also clear, and so they can accelerate.

 

A dangerous assumption there. 

 

The home signal off with a distant at caution may mean that the signalman thinks the train is close to it but is guessing as the home signal is out of sight. 

 

The signalman may also have got a bit keen, or distracted by other movements, who knows. 

 

All that cleared home signal is saying is:

You may proceed past me but I'm saying nothing about the aspect at the next.

 

Expecting things that don't happen ( green signals for instance) can cause all sorts of heartache.

 

Andy

[ikcdab]

On 07/01/2024 at 17:48, The Stationmaster said:

Think of it thos way Karl.  If it is a worked Distant and it is standing at caution the Driver of anapproaching train will be looking out expecting to find the Home Signal at danger.  If it is a worked distant and it is at clear the Driver will expet to find the Home Signal at clear.

 

Now translate that to a Fixed Distant which is always at caution - so doesn't give a clue about the state of the Home Signal so in theory the Driver doesn't know what to expect, so in theory he expects t find the. Home Signal at danger.  But in reality he might well work on the basis that we don't usually get checked here  - so doesn't bother too much about the Home Signal - until he sees it at danger!  Basically a fixed distant does little beyond reminding a Driver where he is and that he is approaching a stop signal.

 

The GWR did things rather differently with Distant Signals because it fixed them at caution, other than at junctions, if there was a restriction of speed to 15 mph or less in Station Limits between the stop signals to which it applied.  Hence on single lines on the GWR distant signals at crossing places were normally fixed at caution because the speed for hand exchange of tokens was restricted to 10 mph

As was the case on the Minehead branch. When Whittaker automatic token changing was installed, the distants became worked.  A cleared distant then not meant a clear line through the loop, but also that the automatic token changing was in use so speeds of up to 40mph were allowed.