[Tagging] access: motorcar and goods, how to read the hierarchy

Martin Koppenhoefer dieterdreist at gmail.com
Fri Feb 17 13:01:13 UTC 2017


2017-02-17 12:26 GMT+01:00 Simon Poole <simon at poole.ch>:

> Mistake #1: assuming that there is a vehicle class hierarchy (of any kind).
>


well, that's what the wiki has in the sentence above the hierarchical
scheme (indentation): "This hierarchy is different in each country."
It might be different, but a hierarchy "of any kind" is likely to exist in
most countries.



> Typically law-makers see no reason to conform to computer science niceties
> when drafting regulations (rightly so) and will simply add or deduct
> vehicle properties in ways that make sense for the regulation in question
> (well most of the time :-)).
>


when it comes to signs with restrictions, drivers can benefit a lot from a
logical hierarchy, because it makes the signs quickly readable.
Otherwise you end up with signs like this:
http://www.laleggepertutti.it/wp-content/uploads/2014/03/cartelli-stradali.png


> The OSM hierarchical approach makes sense from a practical mapping pov,
> but will have issues accurately modelling such edge cases and I would
> suggest just living with that.
>
>
I still believe we should know what the key "motorcar" is meant to describe
(it could also be a country specific definition, must not be valid
globally). There's no definition in the wiki, it only states
"automobile/cars" and a link to wikipedia which is more confusing than
helping.

What does it mean that the "motorhome" is indented in the wiki table with
respect to motorcar, while "goods" is not?

How do I know whether a restriction or allowance for motorcars is valid for
hgv as well? Or shall I add 33 access-tags on every road?
E.g. typically an isolated motorcar=no implicitly means also hgv=no,
goods=no, motorhome=no, agricultural=no, tourist_bus=no, bus=no, ...
while a motorcar=yes does likely not imply anything for hgv or tourist_bus,
but eventually it does for motorhome and goods.

Cheers,
Martin


https://wiki.openstreetmap.org/wiki/Key:motorcar
https://en.wikipedia.org/wiki/Car
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