[Talk-GB] Unfit for motors - tagging for routing

Gregory Williams gregory at gregorywilliams.me.uk
Mon Dec 10 15:11:45 GMT 2012


"motor_vehicle=no" says that motor vehicles aren't legally allowed along the
road. That's not the case as Aidan has pointed out that these are the
blue-backed advisory signs. If going with the commonly-used tags then I
think that, whilst it's still technically not right,
"motor_vehicle=destination" would be a better "hack". However I don't like
hacks.

 

There are several roads near me marked "Unsuitable for HGVs", a similar
blue-backed advisory sign, which I've tagged with "hgv=unsuitable". I don't
know whether any of the routers actually do anything with this at the
moment, but I think that the best tagging for the "Unfit for motors" would
be the equivalent "motor_vehicle=unfit" or "motor_vehicle=unsuitable".
Personally I can't see any difference between saying "unfit" or
"unsuitable", so I'd be tempted to go with the one that's currently got the
greatest number of uses, "motor_vehicle=unsuitable" (though with only 11
uses according to taginfo it's hardly high!; 0 instances of
"motor_vehicle=unfit").

 

I think that changing the class of the road to service isn't the best way of
recording the data. These roads will quite often legally be an unclassified
highway and changing the class away from that just isn't accurate. In my
view it'd be better for the routers to start taking into account the
"x=unsuitable" style of tagging, though I realise that it's the usual
chicken and egg situation here when the use of such tags is currently very
sparse.

 

From: Aidan McGinley [mailto:aidmcgin+openstreetmap at gmail.com] 
Sent: 10 December 2012 14:30
To: cotswolds mapper
Cc: talk-gb
Subject: Re: [Talk-GB] Unfit for motors - tagging for routing

 

 <http://wiki.openstreetmap.org/wiki/Key:motor_vehicle> motor_vehicle=no
should suffice I would have thought?

On 10 December 2012 13:36, cotswolds mapper <osmcotswolds at gmail.com
<mailto:osmcotswolds at gmail.com> > wrote:

There are lots of roads where I map which have "Unfit for motors" signs
(blue/white advisory) but are normal maintained roads in limited but regular
use. Typically they are narrowish, with lots of bends and often steep. In
general anything up to maybe the size of a skip lorry can get through
(though some are too narrow), but what makes them unfit for motors is very
long stretches without passing places,so if you meet something coming the
other way, one of you has a very long, difficult reverse.

 

They are currently tagged in OSM as minor roads, which of course means they
are eligible for routing. As an example, most (all?) routing services (not
just OSM-based, Google Maps has the same problem) will route Chalford Hill
to Stroud along Dark Lane, but Dark Lane has an "Unfit for motors" sign.
It's the shortest and most direct route from the A419 to most of Chalford
Hill, but very few locals use it. 

 

I'd like to tag these roads so that routing services will avoid them, but
can't find any direct way of doing this. I've seen elsewhere that one mapper
has tagged similar roads as Service roads. This has two advantages: routing
services will ignore them(?); and service roads render differently so anyone
using the map visually will be less likely to use these roads. It's pushing
the current definition of service road rather a lot, but if you consider a
service road to be a road that should only be used to access locations
connected to the service road, then it seems within the spirit of the
definition.

 

There's a specific issue with Chalford Hill at the moment. Road closures
(due to collapsed retaining walls) mean that the popular routes to the
valley (Old Neighbourhood and to a lesser extent Coppice Hill) are closed
and likely to remain so for over a month. My local source (a parish
councilor) says that most locals are using a long diversion and avoiding
Dark Lane. (Traffic on Dark Lane has increased, and there was recently a
fist fight when two cars met and neither driver would reverse. Locals want
to make it temporarily one way, which would massively increase its
usefulness, but there's no quick way of doing this.)

 

My two questions:

 

1) Should OSM data discourage use of routes that locals -  who are likely to
be better than outsiders at coping with narrow lanes - avoid as too
problematic;

 

2) Is tagging usable but 'Unfit for motors' roads as service roads an
acceptable way of doing this or is there a better method (that is recognised
by current renderers and routing engines).

 

As my opinion on (1) is yes, I've tagged Dark Lane and a couple of even more
difficult roads as service roads, at least for the duration of the road
closures, but will happily revert the tag if there's a better way.

 

Rob


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