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

cotswolds mapper osmcotswolds at gmail.com
Mon Dec 10 13:36:04 GMT 2012


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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