[Talk-GB] Ground truth v legal truth

Lester Caine lester at lsces.uk
Fri Jul 19 15:43:10 UTC 2019

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.

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?

Lester Caine - G8HFL
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