[Talk-GB] OSM Road Classification - Trunk/Primary

[Andy Townsend]

Hello,

Following a number of complaints to the Data Working Group I've changed 
these back (those that hadn't already been reverted - several mappers 
have changed some back already) in 
https://www.openstreetmap.org/changeset/111266298 and also did some 
manual tidying afterwards (see 
https://www.openstreetmap.org/user/SomeoneElse/history from 111265277 
onwards).  Some of that manual tidying (e.g. gaps in relations) was 
probably fixing issues that already existed prior to any of these changes.

I think that things should be back as they were before now, but if 
anyone sees any remaining issues please let us know.

Best Regards,

Andy (with a Data Working Group hat on)


On 14/09/2021 17:50, Barry McGuire wrote:
> It's strange that the highway=primary tag is used for non-primary 
> routes, and it seems like an historical accident caused by people 
> assuming trunk roads and primary routes are the same thing, when 
> they're not (usually). Trunk roads form part of the strategic road 
> network and are managed by a highways authority (e.g. "National 
> Highways" formerly Highways England, and their relevant counterparts 
> in Wales and Scotland). Primary routes are selected routes between 
> primary destinations. Other A roads are roads connecting important 
> (although not necessarily primary) destinations.
>
> The Scottish OSM maps already have their strategic routes as trunk, 
> with all other A roads as primary, which more closely follows OSM 
> terminology.
>
> In Wales the vast majority of their primary routes are also strategic 
> (trunk) routes, but not all of them.
>
> In England there is a proliferation of roads at the OSM 'trunk' level 
> which isn't seen in most other countries, especially not in town and 
> city centres. Many of the roads are currently tagged as 'trunk' 
> because they're primary routes but they're single carriageway, when 
> OSM usage indicates 'trunk' roads are 'high performance or high 
> importance roads that don't meet the requirement for a motorway'. This 
> implies they should be mostly dual carriageway and high importance, 
> yet fall short of motorway classification (e.g. A1, A11, A12, A14, 
> A19, A2, A20, A23, A27, A30, A31, A34, A35, A38, A4, A47, A66). This 
> further implies that using the 'strategic route' designation for the 
> 'trunk' tag would be more appropriate than using the 'primary route' 
> designation.
>
> Proposal to align UK road types with OSM types as follows:
> OSM Motorway = UK Motorway
> OSM Trunk = UK strategic routes, known as 'trunk' routes (Currently UK 
> primary A roads)
> OSM Primary = All other A roads (Currently UK non-primary A roads)
> OSM Secondary = B roads
>
> Strategic route designations can be found by using data released under 
> OGLv3, just like the NaPTAN data.
>
> There are a few edge cases to consider:-
> * B5093 Mosley Road, Fallowfield, Manchester is designated as a 
> primary route and is also a B road. Resolved by changing to strategic 
> = trunk.
> * B6261 at Shap, Cumbria linking A6 to M6 is designated as a primary 
> route and is also a B road. Resolved by changing to strategic = trunk.
> * A505 and A602 between Stevenage and Luton are not primary routes 
> despite linking two primary destinations. The proposal would place 
> this road on the same level as all other A roads, by abolishing the 
> distinction between 'primary' and 'non-primary' A roads on OSM.
>
> England-Scotland border (West to East) - 2 changes at the border (A7 
> and A68)
> * M6 Motorway
> * A7 primary route (Scotland strategic, England non-strategic)
> * A68 primary route (Scotland strategic, England non-strategic)
> * A697 primary route (Scotland non-strategic, England non-strategic)
> * A1 primary route (Scotland strategic, England strategic)
>
> England-Wales border (North to South) - 1 change at the border (A465)
> * A494 primary (Wales strategic, England strategic)
> * A55 primary (Wales strategic, England strategic)
> * A483 primary (Wales strategic, England strategic)
> * A535 primary (Wales non-strategic, England non-strategic)
> * A5 primary (Wales strategic, England strategic)
> * A483 primary (Wales strategic, England strategic)
> * A458 primary (Wales strategic, England strategic)
> * A44 primary (Wales non-strategic, England non-strategic)
> * A438 primary (Wales non-strategic, England non-strategic)
> * A465 primary (Wales strategic, England non-strategic)
> * A40 primary (Wales strategic, England strategic)
> * A48 primary (Wales non-strategic, England non-strategic)
> * M48 motorway
> * M4 motorway
>
> Changes of designation at borders are not unusual, so I'm not 
> concerned about that.
>
> The only real downsides to this proposal are the work involved (which 
> shouldn't really take too long) and the loss of information about 
> which roads are designed as primary - which is a bit of a false 
> distinction in any case as primary routes do not indicate the actual 
> standard or importance of the road, just that they link two 'primary 
> locations'. Note that 'primary' locations do not mean they they're 
> actually important locations, just that they're useful for navigation 
> purposes (e.g. Scotch Corner as a junction, and Stevenage for itself 
> and the towns around it). The use of those locations for navigation 
> purposes made sense in the 60s but with satnavs etc the standard and 
> relative importance of the road should take priority on maps.
>
> Thanks,
> Barry
>
>
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