Flashing amber

[O L Leigh]

Hi Chaps,

Feathers or Theatre Boxes are used at all junction signals to indicate whether or not a train is to take a diverging route and, where there is more than one possible route, which way you are going. They have nothing to do with the way in which trains are controlled on approach to the junction.

one TN

 

[GeoffM]

I don't believe that I said that the first signal on the diverging route will be held at red.

Um... you did! I didn't make it up!

I simply outlined the normal signal sequence at a junction equipped with 4 aspect flashing yellow signals as it is set out in the Rule Book.

As I mentioned, that a junction signal may or may not clear to a less restrictive aspect than a single yellow (denoting that the first signal on the diverging route is at red) cannot be relied upon no matter how often it may do so under normal operating conditions.

That's correct, I was just suggesting that it is not necessarily at red.

Incidentally, the junction signal does not clear within sighting distance, but will clear normally depending on what type of signal it is.

True in that it varies, but the idea of the joint beyond the AWS ramp is so you get a caution off it before the signal clears. If the routes you drive don't have this then that is slightly unusual - again, perhaps predating current standards. I'll see if I can find the relevant documentation for you.

Geoff M.

 

[O L Leigh]

Um... you did! I didn't make it up!

*Sigh*

I'm not going to argue about what I did or didn't say. The original post is there for everyone to see and to make their own minds up about. I use enough of these junctions to know what they actually do, but I also know from my training and the Rule Book what I should expect if they don't follow to form.

True in that it varies, but the idea of the joint beyond the AWS ramp is so you get a caution off it before the signal clears. If the routes you drive don't have this then that is slightly unusual - again, perhaps predating current standards. I'll see if I can find the relevant documentation for you.

None of the "flashing" junctions I use have this feature, nor any others that I'm aware of. To be honest it sounds more like the arrangement you get at Approach Controlled junctions, where the junction signal clears from a red only once the train has reached a certain point. Forgive me, but were you basing your statement on what Simsig does or do you have railway experience?

Many times the junction signal at a "flashing" junction has cleared to a green long before I get anywhere near the AWS magnet. Even so, as I've stated before, this cannot be assumed. Drivers should always drive as if the junction signal was a single yellow until they can see for themselves what aspect it actually is. Holding it at a single yellow until the train has passed the magnet achieves nothing and could, where the junction speed is particularly high, slow the progress of trains more than is necessary.

Our lines were recently resignalled (in the last 5 years or so, I believe).

one TN

 

[devon_metro]

As for Exeter SimSig, Mike Miles wrote that one so I can't comment. But he is normally pretty thorough with such things.

Geoff M.

Well, being local i'm pretty sure! After the class 45 sped through at about 50 onto the torbay branch with no approcah locking it must be the flashing yellow system!

 

[GeoffM]

I'm not going to argue about what I did or didn't say. The original post is there for everyone to see and to make their own minds up about.

Indeed, so why argue in the first place? I suggest we leave it.

Forgive me, but were you basing your statement on what Simsig does or do you have railway experience?

My full time job is producing formally approved signalling simulations for Network Rail. That involves working through the interlocking data - control tables, aspect sequence charts, etc. Believe me when I say signallers are fussy - and none have ever suggested that our simulations are wrong in terms of flashing yellows. If you let me know which area you work (by email if you prefer) I might have the data for that area at work and I can give you exact details of what the sequence is, where the trigger is, etc.

So, in answer to your question, I have a lot of railway signalling knowledge. You see the lamps on sticks; I see the logic driving those lamps.

Geoff M.
[EDIT]

Is this always the case, looking on Exeter Simsig, there is no flashing amber from DML > Down Torbay where the line speed drops from 60>40, which is 2/3 although it appears to use conventional approach control! Unless this is a fault with Simsig?

Well, being local i'm pretty sure! After the class 45 sped through at about 50 onto the torbay branch with no approcah locking it must be the flashing yellow system!

Okay, point noted. I'll let him know. Thanks.

Doing "about 50" on a 40mph turnout?!

Geoff M.
[EDIT]
Um... that's weird. It was supposed to be two posts and it treated it as an edit!
[EDIT]
Ok, I understand the double posts now.

I have a retraction to make. The release trigger point I mentioned is only when the flashing yellows haven't been active long enough for the driver to see them - ie it only applies under certain circumstances, not all circumstances. So while the special track circuit I mentioned DOES exist at ALL flashing yellow junctions (and near the AWS ramp), it is not used all the time. Apologies for the confusion.

Geoff M.

 

[O L Leigh]

My full time job is producing formally approved signalling simulations for Network Rail. That involves working through the interlocking data - control tables, aspect sequence charts, etc. Believe me when I say signallers are fussy - and none have ever suggested that our simulations are wrong in terms of flashing yellows. If you let me know which area you work (by email if you prefer) I might have the data for that area at work and I can give you exact details of what the sequence is, where the trigger is, etc.

Interesting stuff.

Sorry if I appeared to be having a pop, as that certainly wasn't my intention. It just helps to know at what level to pitch the discussion, as sometimes on forums you find that you have to go all the way back to first principles.

**EDIT**

Geoff: Just seen your clarification. Thanks for that.

one TN

 

[devon_metro]

Okay, point noted. I'll let him know. Thanks.

Doing "about 50" on a 40mph turnout?!

Geoff M.

Well more than 40 through Newton Abbot station so there was still somke braking distance before the 40mph sign.

Quite a nice junction to go over in an HST at 40

 

[Nat the Ned]

Well, being local i'm pretty sure! After the class 45 sped through at about 50 onto the torbay branch with no approcah locking it must be the flashing yellow system!

The only place you'll find flashing yellows in Devon is the signals each side of Totnes, trains will get flashing yellow if signalled into the platforms roads.

 

[960012]

We have them at Cockcrow, round meadowside to U2 u get a flashing double yellow then U1 u get a single yellow then ES u get a green with a feather to go up the spur (the Steepest part of the) then uve got ES17R which only displays yellow or grann as its a repeat, if that yellow it means your going to get stopped at ES17 which you dont want on a loaded train as u cant get going again. So if you see a Yellow on ES17R u tend to hang on the whistle all the way round the bend.

 

[matt]

We have them at Cockcrow, round meadowside to U2 u get a flashing double yellow then U1 u get a single yellow then ES u get a green with a feather to go up the spur (the Steepest part of the) then uve got ES17R which only displays yellow or grann as its a repeat, if that yellow it means your going to get stopped at ES17 which you dont want on a loaded train as u cant get going again. So if you see a Yellow on ES17R u tend to hang on the whistle all the way round the bend.

I was quite impressed at Cockcrow when I saw the flashing aspect

 

[960012]

yes, its wired wen you coem roudn the bend and wen u first look the signals not on lol, its just that yellow at 17R uve got to watch, the whistle is most used then lol

 

[devon_metro]

Well Nat. When a train through plat 2 to Paignton line is set the starter on plat 2 is on Yellow then clears to green when the train reaches it. If it is not flashing yellows before it then what on earth is it? I have witnessed many cases of it know: Blue pullman - winter booked non stop thru NA the BNS-PGN vomit and the 45! So please tell me what it is as i cannot think of an explanation.

 

[Nat the Ned]

Well Nat. When a train through plat 2 to Paignton line is set the starter on plat 2 is on Yellow then clears to green when the train reaches it. If it is not flashing yellows before it then what on earth is it?

Not 100% sure where you are on about, but on all signalling around Newton Abbot diverging routes are feathers. What you see maybe 'approach controlled'. ie yellows are used to slow the train down then clear to green when train nears...

 

[Tomnick]

Well Nat. When a train through plat 2 to Paignton line is set the starter on plat 2 is on Yellow then clears to green when the train reaches it. If it is not flashing yellows before it then what on earth is it?

Not 100% sure where you are on about, but on all signalling around Newton Abbot diverging routes are feathers. What you see maybe 'approach controlled'. ie yellows are used to slow the train down then clear to green when train nears...

You'll find 'feathers' used on the junction signal in all cases of flashing yellows that I'm aware of - including Totnes, I'm sure. A flashing yellow isn't a route indicator - just advance warning that a diverging route is set from the following signal.

I think I've read somewhere that there's three routes, on consecutive signals on the approach to Newton Abbot, signalled with flashing yellows (down main to platform 3 from one signal, down main to platform 1 on the following signal, and finally platform 2 to Paignton line) - Simsig doesn't agree with this though, and it seems unlikely under the 'rules' for flashing yellow (4-aspect) signals.

 

[Nat the Ned]

You'll find 'feathers' used on the junction signal in all cases of flashing yellows that I'm aware of - including Totnes, I'm sure. A flashing yellow isn't a route indicator - just advance warning that a diverging route is set from the following signal.

I think I've read somewhere that there's three routes, on consecutive signals on the approach to Newton Abbot, signalled with flashing yellows (down main to platform 3 from one signal, down main to platform 1 on the following signal, and finally platform 2 to Paignton line) - Simsig doesn't agree with this though, and it seems unlikely under the 'rules' for flashing yellow (4-aspect) signals.

Will check Newton Abbot out next time I'm at work. Yes, flashing yellow is not a route indicator, on the up main approaching Totnes this is the signal that can be a flashing yellow http://www.southwestrails.fotopic.net/p32016008.html (play spot the phone mast disguised as a tree), the next signal then has the feathers......

N

 

[Tomnick]

Will check Newton Abbot out next time I'm at work. Yes, flashing yellow is not a route indicator, on the up main approaching Totnes this is the signal that can be a flashing yellow http://www.southwestrails.fotopic.net/p32016008.html (play spot the phone mast disguised as a tree), the next signal then has the feathers......

N

That's good - just wanted to confirm that we were both on the same wavelength, so to speak!

It'd be good to confirm what the arrangements are around Newton Abbot anyway - I'm not sure either way!

As for that "tree" - hmm...

 

[devon_metro]

Well DM>plat 1 at Newton is deffo approach lock. But plat 2. own torbay is at yellow. And the trains come through at a good 45mph and i don't think you get signals that just go to yellow do you. would have thought it be flashing yellows before. Just out of interest Nat, where do you sign for in terms of guarding?

 

[16CSVT2700]

Didcot Parkway has flashing yellows.

Was on a HST back from Swindon and while paused at Didcot to let punters on/off the 3-aspect signal at the end of p2 was displaying a flashing yellow. We then crossed onto the slow lines and headed to Reading like that.

As an aside what is the speed limit on the slow lines from Didcot to Reading? we must have been doing at least 95/100..

 

[Beaker]

Flashing blues all the way, retb rules

 

[Tom]

Ha. Ha.

Winchester has flashing yellows for the diversionary route at Shawford station (creates the down slow route as far as Eastleigh). Woking also features them as part of Woking Junction Portsmouth diversion.

 

[voyagerdude220]

Didcot Parkway has flashing yellows.

Was on a HST back from Swindon and while paused at Didcot to let punters on/off the 3-aspect signal at the end of p2 was displaying a flashing yellow. We then crossed onto the slow lines and headed to Reading like that.

As an aside what is the speed limit on the slow lines from Didcot to Reading? we must have been doing at least 95/100..

I've got a feeling that at least some of it is 125 mph. It definately seemed very fast when i was stood by the door window on an HST, directly behind the HST PC last time i was along there.

 

[devon_metro]

Ok, heres the evidence that the DM is set at yellow onto DN TBY at Newton Abbot. No train was is the platform. So surely this would be flahing yellow before it. Don't think there is a signalling precedure that just allows green/double yellow>yellow (route diversion)> whatever the next aspect is.

It cleared when 43093 sped through Newton Abbot on the Dn Torbay Express

 

[Brian EWS]

I've got a feeling that at least some of it is 125 mph. It definately seemed very fast when i was stood by the door window on an HST, directly behind the HST PC last time i was along there.

The up and down relief are 100mph from Didcot to Tilehurst. Mind you following a stopper on my freights you might as well stick to 40mph.

As for flashing yellows there is a nice one at Oxford North Jct for the signal into the up platform at 25mph! They are not always for fast junctions.

 

[GeoffM]

i don't think you get signals that just go to yellow do you

Actually, you do. See http://www.rgsonline.co.uk/docushare/dsweb/Get/Rail-24777/RT0032A.PDF section B10.5. As to whether this applies in this situation, it is hard to tell without looking at the signal in rear. But one clue could be as to when the junction signal cleared to less restrictive than yellow - long before the train arrived, or just as it came into sight?

Geoff M.

 

[devon_metro]

As it passes the VT 4/5 stop board on the platform really.

 

[devon_metro]

EDIT Thanks for the PDF, i think that is the case at Newton Abbot. The mystery is finally solved

 

[Bonnie Prince Charlie]

Not disputing that there's flashing yellows at Westerleigh (Simsig shows them too ), but are you sure that the PSR over the diverging route is as low as 20mph? If that was the case, I'd have thought that approach control from red would have been preferred! I know there's quite a few exceptions, but flashing yellow junction signalling was originally intended for locations where approach control from red would be too restrictive, for example a 50-60mph turnout on a 90mph line.

Juncton at Kidsgrove where the route diverges off to crewe has flashing yellows for a 15mph psr

 

[66526]

If you're slowing for a red doing 15 over teh magnet and the linepeed through the junction is 30mph such as at Westerleigh (the 20 is a TSR) then I doubtr that you make up as much time.

 

[Death]

Hail all!
Just to add a bit more fat to the fire, here's another one for you to ponder over... :tongue3:

There is a 4-aspect signal on the western end of Pl. 2 at Brookwood (Don't know the number...Sorry!) which functions normally most of the time. However, it does show a flashing double amber when a train is due to travel down the Mid-Hants branch (I.E: Towards Aldershot, Farnham and Alton) from Pirbright Junction.

Now I don't know the ins and outs of the setup there, but here's a few points:

• I can't remember if this signal is the last one before the junction signal, but given the flashing double amber and the distance to Pirbright Jct from Brookwood (About 2 miles) I would imagine that there could be another signal between the two.
• From what I've observed, the signal enters this state well before the train arrives, and does not clear at least until the train has passed it. However, I always go to Aldershot from Brookwood, and signals aren't easy to observe from where I'm sat in the train!
• I'm guessing that the turnout speed limit for trains leaving the main line at Pirbright Jct is about 25mph, given how slow trains are when heading towards Ash Vale. However, this turnout could easily be taken at over 60mph (125 for tilters) without any safety issues.
• This is the only flashing double amber that I've ever known about, unless others have been mentioned in this thread and I've missed it!

I don't know if this'll help the debate at all, but can anyone tell me why trains take Pirbright Jct so slowly when they could easily do thrice their current speed without problems? Cheers! 8)

Farewell...
>> Death <<

 

[Tomnick]

If it's a flashing amber light, you're probably mistaking it for a pelican crossing on the road outside the station

Now I've got that one out of the way , I'll go through your points...

• Yep, there will be another signal before Pirbright Jn. - that'll display a single flashing yellow when the route's set for the diverging route at the junction itself. The signal following that will obviously be the junction signal itself - it'll most probably be held at yellow (with 'feather' lit) until the train's passed the AWS magnet, when it'll clear to a green as long as subsequent signals allow.
  
• The signal in question will show a flashing double yellow aspect as soon as the junction signal is cleared for the diverging route, whether a train's approaching or not (in fact, if a train is closely approaching at the time, it might not start flashing - that's another story!). It'll continue to show that aspect until it's replaced to danger by the passage of the train, just as any other signal would be replaced to danger. Obviously, though, if the route is cancelled at the junction, then the signal will revert to steady double yellow.
  
• There's all sorts of reasons why the speed over the diverging route might only be 25mph (I don't know the junction in question!) - it's not just the curve of the diverging route, but also the turnout itself. It might be safe for more than 25mph, but that doesn't mean it'll be hugely comfortable. And you wouldn't want to upset the Alton Line lot, would you?
  
• Finally, yep - I can name quite a few other examples!