Signal Ahead! sign

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Russardo

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Hi all.

On the Ayr to Glasgow line I noticed at least two triangular signs that are yellow, with a black border and black exclamation mark "!" in the middle (if I remember correctly). Underneath the triangle it says "signal ahead". The sign seems quite a distance away from the actual signal and was on a straight line (although there are some bridges that may restrict the drivers view of the signals). With AWS etc and the fact that it's a four aspect line I was wondering why these were introduced? (as I have only noticed them recently).
 
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O L Leigh

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Hi Russardo,

They are usually used where the signal sighting is particularly poor, and where the signal could have possibly been SPAD'ed in the recent past. They are there just to remind the driver of the location of the next signal where this might not otherwise be obvious.

There are at least two similar instances on my routes. One for a signal around a tight bend and the second where the next signal is obscured by a road bridge and the next signal beyond that is visible to the driver first.

HTH

one TN
 

nutter

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There is also one just after okengates (wolves to shrewsbury line) station warning (MJ 354 IIRC) is 732 yards ahead. Visability of the signal is normal with no obsticles in the way, and it isn't on a particulary tight curve.
 

O L Leigh

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Hi Nutter,

There may be line of sight issues that are only obvious from the driver's seat, or possibly some other local problems with sighting that signal. Line curvature and viewing obstructions are just the particular problems at the locations I was referring to. It was by no means an exhaustive list. ;)

one TN
 

nutter

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Cheers for putting me straight one TN. On tuesday i'll have a proper look (from the passanger seat :cry:) and see if i can see any obstruction. It is on a overhead cantenary style support to the left of the line. But as you said, I might not be able to see any obstruction clearly. Could it be because the distant (600 yards before) is not that clear in certain light.
 

O L Leigh

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Glad to help. Let me know what you discover. :)

The distance could be an issue, especially at night. I drive on lines with OHLE and tend to use the stanchions as a guide to how far I am from any particular signal and usually aim to stop at the stanchion before if the signal is at red. Where there is no OHLE or any other way of judging your distance from a signal, such markers could be very useful. At night, colour light signals are very bright and, if there are no other signals around, it can be hard to judge exactly where a signal might be. However, in that situation I would prefer countdown marker boards (like on the motorway before an exit) rather than a board telling me I was 632 yards away.

one TN
 

nutter

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Just passed the signal in a forward facing seat and sighting is clear a good 450 yards before the signal as it is raised and the land on the left (the inside of the slight curve) looks as if there used to be a siding there. If i can see it clearly from way back then surely a train driver doing their job should be able to see it as well. Never mind, the sign is there because it's there i suppose
 

Techniquest

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A slight curve you say? Could be a good reason for it to be there. Depends on what other signals are in the area, what the signal might be protecting, all manners.

As for the 632 yards sign, someone's being a bit precise there I'd say.

Best way to find out is to be cheeky and ask a driver on the route what it's there for I'd say.
 

nutter

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The curve has a rough radius of about 2km. The reason why the sign is so precise is because it is on the end of Okengates down platform, so they could just use the platform as a mark to measure from. The sign could be there to remind drivers of all stations trains that the signal exists.

I have edited the first post but for those who get confused why FGWfan says 632 yards to the signal it's because thats what I thought the sign said before I saw it from an all stations today (and so passed it at slow speed)
 

nutter

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There are no other down signals on the curve. There is the distant between 1 and 2 km before the signal and a YY to slow trains down for Wellington about 1.5km down the line, out of sight due to the curve. The British railways should become known as the 8th wonder of the world :lol:
 

O L Leigh

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Nutter,

Sorry, but that just doesn't add up. The driver will know that the signal is there from his/her route knowledge. Besides, those signs aren't put out for that reason.

I suggest that the view of the signal is very different from the driving seat than from any other viewpoint within the train. As someone else has suggested, asking a driver might be the only way to settle this one (assuming one is willing to talk about it).

one TN
 

Tomnick

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Wherever I've seen a 'signal ahead' sign, it was on the approach to a signal that might have had restricted visibility for various reasons (as oneTN's suggested more than once!) - possibly used where signals have a SPAD history for that reason? One example I can think of is at New Mills east of Manchester - the first signal after a diverging junction follows a pretty sharp curve (and an overbridge, I think), and with the restricted visibility I suppose it could be potentially easy for a driver to open up after the PSR at the junction, temporarily overlooking the fact that he's just had a single yellow at the junction signal - the 'signal ahead' sign just acts as an extra reminder of a slightly obscured signal, I suppose.
 

Techniquest

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It's a rare instance of sense coming first, tied with safety, in the industry. As Tomnick has said, and oneTN more than twice, it's only there to act as a reminder, something to fall back on. 'I didn't know the signal was coming' 'There was a sign reminding you of this at the junction'.
 

NumptyDriver

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You're mostly barking up the right trees here - 'Idiot Boards' as they're sometimes affectionately known are usually put in place as spad mitigation attempts for multispad-ed signals, which of course can be for a variety of reasons. they're usually on open running lines where visibility is restricted or where there's a risk of driver inattention/distraction. There are a few dotted around the Manchester area where i drive, one approaching Dean Lane station on the down where there's a reduction in speed to 25mph over thorpes bridge junction, followed by a 60mph where inattention could lead to a driver opening up against the red, which has very restricted visibility under dean lane road bridge. There's another approaching Lostock Junction on the down where the signal has restricted visibility due to curvature of the line and foliage, the linespeed here is 75mph and it's a long signal section from the previous signal where trains would still be accelerating after leaving bolton. These boards are not infallible as has been unfortunately proven by a recent spad in the guide bridge area. I don't sign that area yet but from what i've heard the driver set off from a platform with a single yellow at the end, negotiated a crossover at 25mph, opened it right up and only saw the red when it was too late at about 50-odd mph, the train passing the signal by about 30 yards after the TPWS activation, this signal apparently has 3 countdown marker boards on approach.

It's a case of 'every little helps', obviously a driver should react to every cautionary signal in some way (this helps as a reminder - doing something different ie reducing from notch 7 to notch 6 when accelerating after passing a double yellow for example, or coasting, or braking, whatever's appropriate) but drivers are human beings and human beings are not robots - better drivers than me have had spads i'm sure and thinking that way and being professional will help me to (hopefully) avoid spad-traps. Route knowledge is absolutely invaluable. All drivers will be aware that signals exist, not every driver will be able to pin down the exact location of every stop signal because some signals just aren't very often at danger. We are all assessed regularly, some assessments involving route-conducting/map drawing and i can tell you that any driver who misses out a main-aspect running signal, especially a multi-spad, will fail assessments.
 
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