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

[Chris Hodges]

Those roads caught my eye, as I know them both.

They're both a little odd.  The first (my ex lived on Moseley road 20+ 
years ago) looks like it should be an A road - it's a continuation of 
the A6010 Wilbraham Road connecting to the A34, but the A6010 turns 
north and becomes Wilmslow Road (before turning east again to meet the 
A34, but the capacity isn't great IIRC).


At Shap (I cycled some of that B6261 last month onto the A6), it's a 
short link between two important (deliberately vague term) routes.  I'm 
pretty sure the designation "B6261" predates the existence of the M6, so 
the numbering was kept the same, but the road grew in importance.  This 
is common, the redesignation as primary isn't.


Funnily enough the OS maps aren't consistent here: the 1:50,000 shows 
the B6261 as primary (green, as the A6), while the 1:25,000 uses the B 
road orange.  In Manchester the dual carriageway B road is orange on the 
1:50,000 as well.


Chris




On 15/09/2021 10:09, Barry McGuire wrote:
> Hi Paul,
> to the A6010
> There are two sections of primary B roads that I've been able to find, 
> which is against the Government's own advice for primary routes:
> * B5093 Mosley Road, Fallowfield, Manchester is designated as a 
> primary route and is also a B road.
> * B6261 at Shap, Cumbria linking A6 to M6 is designated as a primary 
> route and is also a B road.
>
> The proposed change would make UK OSM consistent with the global OSM 
> terminology (i.e. a trunk road is a high performance or high 
> importance road that doesn't meet the requirements for motorway). Many 
> of the UK's primary routes (tagged on OSM as 'trunk') are relatively 
> minor roads (single carriageway, multiple roundabouts, 30mph limits) 
> and there is no way those should be classed as 'trunk'. There are some 
> non-strategic primary routes that are dual carriageways with grade 
> separated junctions and national speed limit (i.e. OSM 'trunk' 
> standard), but they're in the minority.
>
> The proposed change has the added benefit of making the UK OSM 
> definition consistent with UK terminology, which has long term benefits.
>
> It has been noted that OS maps distinguish between primary and 
> non-primary. Is the global aim of OSM to replicate in-country mapping 
> standards or to create a consistent map as possible globally? The 
> guidance for East Africa states "In Kenya, despite the official 
> designation International Trunk Roads, most of type A roads are not 
> trunks as defined by OSM. The vast majority of Kenyan A roads must 
> fall into the category highway=primary." To me this indicates OSM is 
> aiming for a consistent standard internationally, and currently the UK 
> (well, mostly just England) sticks out as not applying the 'trunk' tag 
> to the required standards.
>
> As Tom said this is a matter that keeps being raised so it's clearly a 
> persistent issue that needs resolving.
>
> Barry
>
> On Wed, 15 Sep 2021, 09:21 Paul Berry, <pmberry2007 at gmail.com 
> <mailto:pmberry2007 at gmail.com>> wrote:
>
>     > Retaining the current system produces the quirks mentioned
>     previously e.g. primary B roads and routes between primary
>     destinations not being primary, which are difficult to handle - in
>     fact each of the primary B roads are designated differently on OSM
>     (one as trunk and one as secondary).
>
>     If you're going to open this can of worms, at least get your
>     definitions right. There's no such thing as a primary B road. Only
>     A roads can be primary and non-primary.
>
>     The system isn't great but there's a lot to be said for OSM in
>     being consistent, even if it's not as we would have designed it if
>     we were starting from scratch.
>
>     Pick your battles wisely.
>
>     Regards,
>     /Paul/
>
>
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