Why do motorway fork signs not include the motorway number?

[crazyknightsfan]

Something that has always nagged at me - why do fork signs on UK motorways not include the motorway number for the through/straight direction?

Even where the motorway number changes (e.g. M6 becomes A74(M)) it's not shown.

Just a historical quirk?

[Euan]

The M6/A74(M) case is most likely just to avoid any confusion amongst drivers continuing along the motorway beyond the junction - if they suddenly caught a glimpse of a new number on the same continuous road after hundreds of miles they may feel like they have gone the wrong way. Either that or there is just simply not enough room on the sign to include the number alongside the word "SCOTLAND", as is the case on some signs further south on the M6.

Note this sign on the A75 as well:

https://www.google.co.uk/maps/@54.99978 ... 312!8i6656

The motorway south of J22 is not given a number on the sign, just an indication that it leads onto the M6 with "(M6)" shown on the sign. Even though the motorway across the border is officially numbered A74(M), it is almost made to look like the motorway is numberless when crossing the border and does not become the M6/A74(M) until after the first junction on the south/north side.

[J N Winkler]

Not showing the through route number on the FADS is a convention dating back to the Anderson committee's decision to adapt the German approach of progressive development of direction information in the advance signing sequence rather than the American one of carbon-copying destination legend across the exit direction sign (equivalent to a FADS in the UK) and all advance guide signs. Unlike the case in America, where the exit direction sign is clearly distinguished from the advance guide signs by an arrow, the FADS has the same format (including fork graphic) as the ADS, so it is differentiated from them by the absence both of a through route number and a mileage indication.

[Robert Kilcoyne]

Although the A74(M) is not signed as the straight ahead route at M6 Junction 45, you would see this fork sign on the A74(M) less than ten miles later:-

https://www.google.co.uk/maps/@55.04933 ... 6656?hl=en

and at the next exit:-

https://www.google.co.uk/maps/@55.06263 ... 6656?hl=en

The fork signs on the southbound carriageway at Junctions 19 and 20 also show A74(M) as the signed route straight ahead.

https://www.google.co.uk/maps/@55.06685 ... 6656?hl=en

The M74 is not signed as the straight ahead route at Junction 13 (Abington) travelling north, and the A74(M) is not signed as the straight ahead route at Junction 13 travelling south. The only indication that the motorway number has changed is the chopsticks sign after the exit slip road.

[Johnathan404]

I can see the argument that it's not needed because motorways regularly remind you of their number (now every 500 metres), there aren't many exits and when there are it's usually pretty clear which way the road continues.

Equally I think most people can't remember why we do it and it's just one of the things we do.

[Conekicker]

The ahead route number is, however, shown when gantries are present. With the increasing number of Smart Motorways, they will become more common.

[Viator]

Not showing the through route number on the FADS is a convention dating back to the Anderson committee's decision to adapt the German approach of progressive development of direction information in the advance signing sequence rather than the American one of carbon-copying destination legend across the exit direction sign (equivalent to a FADS in the UK) and all advance guide signs. Unlike the case in America, where the exit direction sign is clearly distinguished from the advance guide signs by an arrow, the FADS has the same format (including fork graphic) as the ADS, so it is differentiated from them by the absence both of a through route number and a mileage indication.

Showing my ignorance again, but: FADS? A quick Google search turned up "Far Advance ..." (Qatar) and "Final Advance ..." (Hong Kong).
(As my dad's old Reader's Digests used to say: It Pays to Increase Your Word Power)

[J N Winkler]

Showing my ignorance again, but: FADS? A quick Google search turned up "Far Advance ..." (Qatar) and "Final Advance ..." (Hong Kong). (As my dad's old Reader's Digests used to say: It Pays to Increase Your Word Power)

In terms of the example diagrams in TSRGD 2002 Schedule 7 Part X (motorway signs):

ADS = advance direction sign = ground-mounted fork sign to Diagram 2903 with distance

FADS = final advance direction sign = ground-mounted fork sign to Diagram 2906 without distance

By long convention (dating back to the Motorway Design Memorandum that was in samizdat circulation instead of being formally published), there is a first ADS with just side route number (e.g., "A52"), then at least one further ADS with side route number and destination (e.g., "Nottingham A52"), and a FADS with route number and destination for side and destination only for ahead. But, as Conekicker notes, things work differently for overhead signs, which are under different diagram numbers.

[brombeer]

The green FADS on expressways are also from a different series and will contain the A-number on which you find yourself. The combination of "blue FADS no / green FADS and gantries yes" has always struck me as somewhat odd. Somewhat discards the reasoning for leaving them out on the blue FADS too.

Personally, I understand that rationale, but a motorway number is just about the quickest bit of route confirmation that you can give, much more predictable too in comparison with the PDs ahead that they often come up with. It wouldn't really eat into space much needed for something else either.

[Euan]

I can see the argument that it's not needed because motorways regularly remind you of their number (now every 500 metres), there aren't many exits and when there are it's usually pretty clear which way the road continues.

Not in Scotland - from what I have seen, none of the motorways here have any km marker posts. Without them, it is pretty much down to the route confirmation signs for the motorway number to be identified and these can quite often be absent after a junction where they would be expected to appear. I don't think the km signs are used on the M4 in Wales either, or indeed at all on any of the NI motorways. Although having said that they are to be found on RoI motorways.

[brombeer]

At a minimum, these km signs came into being many years after the blue fork signs were designed, so it must have been factored into the system that you would only see the M-number on RCSs. But still that is defensible, if you look at a road number as something that above all serves to help you onto the right road, because you cannot anticipate which destinations will be signposted upon your approach but you will instantly recognise the number. In this reasoning, once you've taken the right exit, you'd switch to looking for destinations ahead (or your next road number) rather than confirmation of your M-number. This is why on Italian signs the road number disappears completely from the directional signage once you are on a particular numbered road - be it on green signs or blue. And then Italy doesn't really have RCSs to reconfirm the number either.

[crazyknightsfan]

Thanks to all for the very interesting replies.
It does seem like the answer is 'historical quirk' and that context was quite interesting, JN Winkler. Now it just seems to be a piece of important information missing from major direction signs. As someone else noted above, it's not like it would require much additional room on signs to include it.
Very interesting to see the examples from Scotland where the Motorway Number does appear on the signs!

As a side note, the NSW (Australia) approach to signing motorway exits does draw heavily on the UK motorway signage - i.e. an initial ADS at 2km with only destinations for the exit, then a second ADS at 1km with destination for the through direction as well. On the earliest signs the 2km ADS sometimes had the shorter version with no number straight ahead but I haven't seen those used since at least the 1980s.

[nodnirG kraM]

Very advanced warning if you head left for Toronto and straight on for Newcastle...

[Bryn666]

Motorway signs were designed before the corresponding A-road signs, so it is a historical quirk.

Remember the only places on an Anderson-era sign system you'd see a motorway number were:

1. Approach ADS, these were all blue despite being on an all-purpose road. The Preston experiment of using a white background and blue panel for the motorway was abandoned for the M1 and beyond.
2. Route confirmation sign in the central reservation located after the entry slip road. Mileage signs mounted on the nearside verge did not feature a motorway number.

The start of motorway signs simply used the word "Motorway", except on the M1 and seemingly A20(M), which used "Prohibited on motorway" and a list, instead of the big "NO" and list (which was used at Preston).

I should do a detailed write-up on this on t'blog. Maybe a job for tomorrow evening when I've nothing to do post-IHE conference.

[crazyknightsfan]

Motorway signs were designed before the corresponding A-road signs, so it is a historical quirk.

Remember the only places on an Anderson-era sign system you'd see a motorway number were:

1. Approach ADS, these were all blue despite being on an all-purpose road. The Preston experiment of using a white background and blue panel for the motorway was abandoned for the M1 and beyond.
2. Route confirmation sign in the central reservation located after the entry slip road. Mileage signs mounted on the nearside verge did not feature a motorway number.

The start of motorway signs simply used the word "Motorway", except on the M1 and seemingly A20(M), which used "Prohibited on motorway" and a list, instead of the big "NO" and list (which was used at Preston).

I should do a detailed write-up on this on t'blog. Maybe a job for tomorrow evening when I've nothing to do post-IHE conference.

Look forward to reading that
The Anderson-era signage reminds me of US interstate-style signage - if there are no gantries then the only time you would see the interstate (or US) number would be on RCS/trailblazer type signs. The mileage signs in the US still don't have the route number.