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

[Andy Allan]

On 17 December 2012 14:35, cotswolds mapper <osmcotswolds at gmail.com> wrote:

> Of the various views, I tend to like highway=service +
> designation=unclassified_highway as the most useful.

> I agree highway=service is unsatisfactory, but with
> designation=unclassified_highway it seems the least worst route to a helpful
> map.

I don't normally get involved in tagging discussions, but I have to
disagree here. There is an objective fact to record ("the road is
signed as unsuitable for HGVs") and the tagging should express this
fact in a clear and simple fashion.

There is nothing about the highway=service tag suggests or implies
that these roads are unfit for HGVs. In fact, large numbers of service
roads exist that are perfectly suitable for HGVs, around industrial
estates and so on. Moreover your original example of Dark Lane is
where it's signed "unsuitable for motors", and again nothing about the
highway=service tag that implies that you can't drive motor vehicles
down them - the vast majority of service roads are designed for motor
vehicles! Adding a "designation=unclassified_highway" again doesn't
have anything to do with hgvs or motor vehicles (and starts to seem
like "oh-no-its-not" tagging, which is frowed upon too).

The "least worst" route is to tag the situation as explicitly as
possible. Personally I would use hgv=unsuitable or
motor_vehicle=unsuitable or long_vehicle=unsuitable, as appropriate.

But "highway=service + designation=unclassified_highway" has got
nothing to do with what you see on the ground, and doesn't record the
facts of the situation. Tagging for mere side-effects of a handful of
current routing implementations is a bad, bad idea. Be as clear, and
as explicit, as possible please.

Cheers,
Andy