Trunk Roads on OS Maps

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Euan
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Trunk Roads on OS Maps

Post by Euan » Tue Jan 08, 2019 09:07

On another thread there was some discussion about the A92 changing from trunk status to local status in Dundee which made me wonder whether there is any definitive criteria for the colouring of trunk roads on OS 50k maps. Is there any reasoning behind the fact that many non-trunk roads are coloured in green on OS 50k maps just the same as roads maintained on a national level?
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nowster
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Re: Trunk Roads on OS Maps

Post by nowster » Tue Jan 08, 2019 09:19

Does green designate trunk or primary?

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Re: Trunk Roads on OS Maps

Post by Chris Bertram » Tue Jan 08, 2019 09:21

nowster wrote:
Tue Jan 08, 2019 09:19
Does green designate trunk or primary?
Primary, I believe. However, in Scotland, my understanding is that with a few rare exceptions, all primary A roads are also trunk.
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Re: Trunk Roads on OS Maps

Post by orudge » Tue Jan 08, 2019 09:24

Yes, since the mid-90s, practically all non-trunk primary roads in Scotland were de-primaried (and some trunk roads were de-trunked). Many maps still seem to show the old statuses (e.g. A91/A92/A93 being primary even though the A92 is the only one with primary sections these days).

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Euan
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Re: Trunk Roads on OS Maps

Post by Euan » Tue Jan 08, 2019 11:52

In Scotland and Wales almost all roads shown in green on OS maps are trunk roads, with a few exceptions. I have noticed that some of the exceptions in Scotland have at least been partially reverted back to red in recent years including the A93, the A7 north of Galashiels and the eastern half of the A71. The A74 in Glasgow between the city centre and Fullarton has bizarrely been left green on OS maps despite the M74 extension having opened nearly 8 years ago now. On mapping from the early 2000s there were fewer non-trunk roads shown in green - roads like the A811, A91 and A952 were shown in red and have since been shown in green suggesting that there might initially have been a rule to colour only trunk roads (Scotland/Wales only) in green and all other A roads in red.

In England there are far more roads shown in green than there are trunk roads and it seems like many of them would be shown in red if they were in Scotland or Wales. Although on the other hand there may be several non-trunk roads in England that would be trunk roads in Scotland or Wales and have been scaled down to take into account the far greater number of roads and volumes of traffic which would make it difficult for England-wide maintenance to work properly as far as that level of priority. In the end the colour of a road on maps might just be chosen to reflect the colour of the signage out on the ground.
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nowster
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Re: Trunk Roads on OS Maps

Post by nowster » Tue Jan 08, 2019 11:58

Primary = green signage. Secondary = white signage.

However, primary is not the same as trunk, except in Scotland. By the way, not all motorways are trunk.

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Re: Trunk Roads on OS Maps

Post by Steven » Tue Jan 08, 2019 16:43

Euan wrote:
Tue Jan 08, 2019 09:07
On another thread there was some discussion about the A92 changing from trunk status to local status in Dundee which made me wonder whether there is any definitive criteria for the colouring of trunk roads on OS 50k maps. Is there any reasoning behind the fact that many non-trunk roads are coloured in green on OS 50k maps just the same as roads maintained on a national level?
Trunk roads aren't mapped on Landrangers these days and haven't been for a while. Primary Routes on the other hand are.

The clue is in the map key!
Last edited by Steven on Tue Jan 08, 2019 19:42, edited 2 times in total.
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From the SABRE Wiki: Trunk road :

A Trunk road (or national road in the Republic of Ireland) is a road maintained by a national government body – as distinct from the great majority of roads, which are maintained by local Highway Authorities. Trunk roads are generally, therefore, the most important roads nationally; for example, most (though not all) British motorways are trunk roads.

An individually numbered road may be a trunk road for all, part, or none of its

... Read More

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Re: Trunk Roads on OS Maps

Post by vlad » Tue Jan 08, 2019 19:41

As Steven has said, the OS don't mark trunk roads on their maps. Green means primary.

Back in days of old they coloured all Class I roads red so didn't distinguish primary roads. They did, however, label trunk roads by appending (T) after the road name. As such, A52 wasn't trunk whereas A52(T) was, even though they were both part of the same A-road.
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Re: Trunk Roads on OS Maps

Post by Chris Bertram » Tue Jan 08, 2019 20:26

vlad wrote:
Tue Jan 08, 2019 19:41
As Steven has said, the OS don't mark trunk roads on their maps. Green means primary.

Back in days of old they coloured all Class I roads red so didn't distinguish primary roads. They did, however, label trunk roads by appending (T) after the road name. As such, A52 wasn't trunk whereas A52(T) was, even though they were both part of the same A-road.
It was, however, never totally clear where trunk status ended. If you knew where a county borough boundary was, you could make a fair guess there, but out in the sticks it could be anywhere.
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Re: Trunk Roads on OS Maps

Post by owen b » Tue Jan 08, 2019 20:38

vlad wrote:
Tue Jan 08, 2019 19:41
As Steven has said, the OS don't mark trunk roads on their maps. Green means primary.
Of course on the 1:25,000 Explorer maps the OS has irritatingly never got round to standardising with the 1:50,000 maps. On the 1:25,000s all A roads are red (red/white for single track A roads).
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Re: Trunk Roads on OS Maps

Post by Chris Bertram » Tue Jan 08, 2019 21:45

owen b wrote:
Tue Jan 08, 2019 20:38
vlad wrote:
Tue Jan 08, 2019 19:41
As Steven has said, the OS don't mark trunk roads on their maps. Green means primary.
Of course on the 1:25,000 Explorer maps the OS has irritatingly never got round to standardising with the 1:50,000 maps. On the 1:25,000s all A roads are red (red/white for single track A roads).
1:25,000 maps are less likely to be used for route planning, so the distinction between primary and non-primary A roads is unimportant. At least they do use red now, older maps used orange, solid for A roads, long dashes for B roads and shorter dashes for higher quality unclassified roads.
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Re: Trunk Roads on OS Maps

Post by Stevie D » Tue Jan 08, 2019 21:55

owen b wrote:
Tue Jan 08, 2019 20:38
Of course on the 1:25,000 Explorer maps the OS has irritatingly never got round to standardising with the 1:50,000 maps. On the 1:25,000s all A roads are red (red/white for single track A roads).
I think this is partly down to practicality and partly down to the different purposes of the maps.

Explorer maps show footpaths, bridleways and byways in green, so there would be a greater risk of confusion if some roads were also shown in green. While there is also that possibility with pink on the Landranger maps, the way that the maps are drawn (particularly around the relative thickness of the different ROWs) makes this less likely.

Landranger maps are more likely to be used by people using the roads such as drivers or cyclists, where the precise road classification may be more relevant, whereas Explorer maps are more likely to be used by walkers, where the distinction between primary and non-primary A roads doesn't make so much difference.

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