[Talk-GB] Ground truth v legal truth

Philip Barnes phil at trigpoint.me.uk
Fri Jul 19 15:59:42 UTC 2019

On Fri, 2019-07-19 at 16:43 +0100, Lester Caine wrote:
> On 19/07/2019 16:04, Philip Barnes wrote:
> > As the sabristi have already discovered this one, and the OSM edits
> > appear linked to Sabre Wiki edits, I will identify it.
> > 
> > In this case I am concentrating on A5191 (Coleham Head, Belle Vue
> > Road,
> > Hereford Road)
> > https://www.openstreetmap.org/#map=18/52.70122/-2.74811
> > 
> > Not a primary on the ground as can be seen on mapillary.
> https://www.sabre-roads.org.uk/wiki/index.php?title=A5191
> As some say, sabre is not an official source but it does use OSM as
> it's 
> mapping tool!
> Essentially this seems like the opposite of my own problem. Around
> here 
> the A46 moved over closer to Evesham, and the old road became the
> B4632. 
> Traffic is then pushed towards the A46 and what can be a 10 mile+
> detour 
> over the other more direct routes linked with the B4632 and even the 
> secondary B4632 is 'avoided' by the routers! In your case the
> preferred 
> route would seem to be the A49 and rather than downgrading the old
> route 
> to a B road it's been left with an A designation? Bottom line is if
> the 
> A5191 is used on traffic reports it should be identified. That it is
> not 
> now a 'preferred route' is a problem, which in practice was screwed
> up 
> by giving it the A5191 designation in the first place, and tagging
> it 
> 'tertiary' IS breaking the rule don't tag for the router :( In the 
> absence of something to override the 'primary' rule set then we are
> a 
> bit stuck, but that should be something additional to what is the 
> documented designation. That the road classifications provide a
> crude 
> rule set for routing has always been a problem but in the case of
> the 
> A5191 what is the speed limit? I think I would expect 30MPH if it is 
> essentially 'residential' which should push routing to faster 
> alternatives, but we are now seeing 20MPH zones even on primary roads
> to 
> calm traffic and provide direct rules for routing?
Looking through the history this road has been mapped as tertiary since
2008, several local mappers have touched it but until one remote
mapper, nobody had considered it to be primary.

Phil (trigpoint)

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