[OSM-talk-be] sidewalk as ways or tags

[Ben Laenen]

Renaud MICHEL wrote:
> You mean that a pedestrian is allowed to cross aven a national road
> anywhere he wants, and even walk on it?

Walk on it: at certain conditions, yes: no sidewalk that can be walked on, no 
walkable shoulders, and no traffic signs explicitly forbidding it. Also have 
to walk left on the road I think.

Crossing it: no traffic signs forbidding pedestrian access (motorway, 
motorroad, no pedestrians allowed) and no crossing closer than 30 meters.


> I have always thought that (and acted acordingly), if a crossing (be it
> controlled or not) is close enough you may not cross the road but must take
> the crossing. (close enough beeing around 50-100m, but I don't remember
> exactly)

Yeah, in my memory it was 30 meters. But I don't know many big roads that have 
a crossing every 60 meters.

> > Also, only put a tag like foot=no on the road when there are signs
> > explicitly forbidding pedestrians on the road. [...]
> 
> Well, my reasoning was that, as I had mapped separately the walking part,
> that the main road sould not be used for walking.

(warning: it gets ugly here if you're not closely familiar with access tags)

And I can understand that logic, but here's the tricky part: osm access tags 
are not simple tags just telling whether X is allowed or not... They have 
another meaning, and in the case of foot=no on a normal road it means that 
there is a sign C19 that forbids pedestrians to use the road (and with such a 
sign this actually means the entire road, so including the sidewalks if there 
are some).

The two may look very similar, but as said above: with the traffic sign 
pedestrians cannot cross or use the road at all. Without the sign, they can 
given the conditions above. So that's why we need to have the distinction.

Likewise, you don't add bicycle=no to a road if there's a cycleway (and people 
who did this are also often incorrect in their way of thinking, since they 
very likely discarded access for mopeds).


Given non-subjective data, a router would just see that there's a footway or 
cycleway which is part of the road and direct you there, and it wouldn't need 
tricks like foot=no. And it should see that there's a crossing close enough 
and let you use it.

> OK, I don't really understand your point about linking to a road,

Well, read my previous paragraph: a router has to know whether that footway or 
cycleway is part of the road or not. If it is, then the router should give you 
directions to follow them. If it's not, then a pedestrian could make use of 
the road, or the footway which in this case is another road that happens to 
run parallel to the main road.

(And I just realize some parts may read ambiguously since there's no English 
word to make the distinction between road as in the entire public area between 
parcels including the part where the cars drive, cycleway, sidewalks, verges 
etc., and road as in just the part where cars drive...)

Greetings
Ben