A few, simple questions about signals

[DaveNewcastle]

. . . .
In fact I think it probably means there are two intermediate block stop signals between successive signal boxes. Another example of sloppy use of railway jargon.

That would appear to fit the circumstances.

There's a box at each end of the two track section (at Blair Atholl and Dalwhinnie), there's signals at at least two points in between those end points, and an exceptionally high risk of incident in between (steep gradients either side of the pass, and the potential for deep snow and poor visibility) and with other special instructions in place (drivers exiting that section in either direction are required to contact the local signaller to confirm that the entire train has made it in one piece!).

Thanks for that.

 

[Tomnick]

Is the requirement to contact the signalman to advise 'train complete' merely because trains are likely to be detained (waiting for the single line?) before the tail lamp passes the box? Not particular unusual, and certainly unconnected with the gradients, if so. Seeing the tail lamp (or being advised as above), of course, proves that the train has left the section intact and allows the signalman to send 'train out of section' to the box in rear.

 

[DaveNewcastle]

Is the requirement to contact the signalman to advise 'train complete' merely because . . . . .

I'm sorry that I can't answer your question.
But I can confirm that the Highland Main Line is single track at either end of that section, that there is a box at either end, and that the Special Instructions state "Blair Atholl. When an Up train is brought to a stand at the Up platform, the driver must immediately advise the signaller that the train is complete with tail lamp attached." and the mirror opposite instruction at Dalwhinnie at the other end.

[This instruction would not normally apply to East Coast's HSTs, or the Sleeper, as they don't call at Blair Atholl or Dalwhinnie]

 

[Zoe]

In fact I think it probably means there are two intermediate block stop signals between successive signal boxes.

There are indeed two Intermediate Block Home signals between Blair Athol and Dalwhinnie, these are at Dalnacardoch and Dalnaspidal.

 

[Welshman]

I am definately certain! You have named 5 stations there which have starter signals. How about st Neots, sandy, shepreth, harringa, arlsey, cuffley, Bayford, crewes hill, welham green, oakleigh park, baldock, new southgate... There is 12 stations which all have a platform with no signal visible from the platform.

As I say, with the exception of junction stations and major stations, any starter signals are generally a coincidence rather than deliberate. Many stations have a signal visible but which is a long way out of the platform so not a starter signal.

Continue down the East Coast Main line to Grantham, where you find that, presumably because of the braking distance from the previous signal protecting the cross-over from the Nottingham line just to the south of the station, the next signal on the down main is way beyond the station, and actually protects the crossover from platform 4 loop back on to the main line.

There's no way that signal can be sighted by either the guard or the driver on leaving Grantham, so if the train has been cautioned at the south end of the station, it moves very slowly indeed around the bend until the aspect can be seen.

And, as that bend is canted for I think 100 mph running, it can be an interesting experience creeping round it!

 

[Tomnick]

I'm sorry that I can't answer your question.
But I can confirm that the Highland Main Line is single track at either end of that section, that there is a box at either end, and that the Special Instructions state "Blair Atholl. When an Up train is brought to a stand at the Up platform, the driver must immediately advise the signaller that the train is complete with tail lamp attached." and the mirror opposite instruction at Dalwhinnie at the other end.

[This instruction would not normally apply to East Coast's HSTs, or the Sleeper, as they don't call at Blair Atholl or Dalwhinnie]

Thanks, always interesting to read about the method of working in different areas. That does indeed, though, seem to be just a means of advising the signalman that the train's complete (which, on an Absolute Block line, must be ensured - usually by observing the tail lamp directly - before a following train can be accepted, regardless of the gradients in the section).

 

[455driver]

On a similar note-

Whenever pilotman working is in operation he will always say to the signalman "1A23 arrived at <where-ever> complete with taillamp",
Even when its a multiple unit which wouldnt be able to arrive if it wasnt complete due to the braking system employed.

Its in the rule book so that is what is done.

 

[Tomnick]

Indeed, the tail lamp is as important as ever on lines where there's no continuous train detection! I think one exception was the tokenless block between Salisbury and Exeter, where trains left the single line at a couple of locations where the tail lamp couldn't be observed - deemed acceptable because of the minimal risk of the trains used on that line becoming divided and not being brought to a stand as a result, if I remember correctly.

That said, I've read about at least a couple of cases where a train formed of 15x units has divided on the move, and the front portion has continued unchecked - something to do with the 'uncouple' button, I think?

 

[edwin_m]

I'm sorry that I can't answer your question.
But I can confirm that the Highland Main Line is single track at either end of that section, that there is a box at either end, and that the Special Instructions state "Blair Atholl. When an Up train is brought to a stand at the Up platform, the driver must immediately advise the signaller that the train is complete with tail lamp attached." and the mirror opposite instruction at Dalwhinnie at the other end.

[This instruction would not normally apply to East Coast's HSTs, or the Sleeper, as they don't call at Blair Atholl or Dalwhinnie]

The signal box at Blair Atholl is at the Perth end of the platforms so the signaller won't see the tail lamp on an Up train until it leaves the platform. At Dalwhinnie it's at the Inverness end so the same applies to Down trains. As soon as the train is confirmed complete, the last Intermediate Block signal can be cleared so a following train can approach the station (assuming the platforms are beyond the clearing point).

 

[SussexMan]

Also, as a little aside, trains MUST NOT be despatched from [Birmingham New Street] on anything but a green. That doesn't stop NS despatchers trying to get you to leave on a yellow, mind.

Can someone explain why.

 

[A-driver]

Can someone explain why.

Not sure why at bns but at London bridge low level there is (or at least was) a rule never to dispatch/leave on a yellow as there are gaps in the conductor rail and stopping at the next red is very likely to gap a unit. Not sure if BNS is to prevent trains being held in a platform with doors closed although at Cambridge it's fairly common to leave plat 4 on a yellow and sit in platform 1 at a red for a minute or so.

 

[The Planner]

Some platforms at New St have two signals in close succession at the platform ends, may be to do with that.

 

[edwin_m]

Is it that the next signal beyond the platform is less than a train length beyond the station throat, so if a train gets stopped there it will be trailing back and blocking the route of other trains?

 

[The Planner]

This is what I mean. Trains are normally behind the horizontal signal when in the platform so you don't want to be going on a yellow!
Photo

 

[Toots]

Most stations have what you would call a Home signal (before entering the station) and a starter signal (to leave the station). No idea what broadgage is on about. hock:

No they don't, a Home signal lies at the end of an Absolute Block section,and a Starter or Section signal,is at the beginning of an Absolute Block Section or an Intermediate Block section.You can have several stations in an AB section.The confusing part is that the portion of line between the Home and Section signals is called the 'Station Limits',but in the signalling sense, this doesn't actually have anything to do with stations at all.....

 

[Llanigraham]

Well done Toots! Would you like a job?

I suggest a few people need to sit down and read this web site:
http://www.signalbox.org/

 

[Railsigns]

There is a starter so far beyond the north end of Blair Atholl station and slightly round a curve to the right, that I'm not convinced that a guard on the platform could see round the curve far enough to see the signal. I've never remembered to ask a guard there if it really is a starter, or a section just happens to start near the station. (It may protect the crossover a mile ahead). Anyone here know the area?

The Down Section signal does protect the crossover. Here's the signal box diagram, also showing the two consecutive intermediate block sections:

 

[DaveNewcastle]

The Down Section signal does protect the crossover. Here's the signal box diagram, also showing the two consecutive intermediate block sections:

Excellent!
You've answered two questions at once.
Thanks.