[Tagging] RFC - Feature Proposal - area of steps for pedestrians.

Warin 61sundowner at gmail.com
Sat Mar 30 01:08:09 UTC 2019

On 30/03/19 11:13, Nick Bolten wrote:
> I like the idea of addressing the area-ness of steps! Thanks for 
> taking the initiative on this. I have a couple questions and ideas 
> that are hopefully helpful.
> # curb (kerb) lines
> What would you think of tagging each step way as a kerb line? e.g., 
> each step way could be barrier=kerb, kerb=raised, and could have other 
> relevant kerb tags like kerb:height.
> This would make it very easy to know what tags to use for virtually 
> any curb-like feature in OSM with non-trivial length: make it a curb 
> line. This would also dovetail with other curb line conventions, such 
> as knowing which side is higher (the side on the right of the way).

Rather tedious to map anything other than a straight line! See the 
Queluz National Palace for example. Or relation 9443810 - it turns 3 
right angle corners..
> # Determining upper/lower steps + number of members
> The example says you would set one step to role=lower and one to 
> role=upper. Does this mean that the relation effectively applies to a 
> single step?

No. It applies to a set of steps ... you map the top and bottom and 
identify each. You could do it .. very small area! For a single step I'd 
rather go with your barrier curb idea.

> On a stairway, a single vertical part of a step could of course serve 
> as both upper and lower, so we'd need more information if a single 
> relation described the whole stairway.
> As a follow-up, what about using the order of relation members, like 
> how bus routes do? This might make it easier to map whole stairways: 
> order = ascending (literally). You could then use the role to describe 
> segments if the stairway splits, though a role like role=1 might be off.

err does not work. They form a closed way. As such one lateral will be 
connecting from top to bottom, while the other will be connecting from 
bottom to top.
Best to have the direction of the lateral way point upwards, but even 
that does not matter as the top is identified by the role in the 
relation as is the bottom.
> # one-to-one way nodes?
> For mapping a step, the proposal says, "Create 2 ways, one for the 
> upper part of the steps, another for the lower. They should have the 
> same number of nodes and have the same direction."
> I'm wondering why they need to have the same number of nodes. It seems 
> to me that the Queluz National Palace example would actually be 
> impossible to map as a single area this way, since it splits into two 
> stairways at the top. But I might be misunderstanding the proposal.
Err no you don't misunderstand it. I think it is a function for the 
renders to ease drawing of these non linear ways such as the Queluz 
National Palace example, connections between the upper and lower way 
nodes form the point where rendering lines change direction...

The Queluz National Palace example needs 3 areas to be defined. But the 
present imagery does not have enough definition for me to do that. I 
have roughly done th elower bit, the upper two are simple ways..

The Sydney Opera House has quite a few steps - not all of them mapped. 
But they are much easier to map being larger + linear and with the 
better imagery we have with the NSW LPI Imagery. I have just done 
relation 9443810 for a set as mentioned above.

> # In combination with one or more highway=steps ways
> It's fairly complicated to route on areas, and this one in particular 
> seems even moreso. What would you think of recommending mapping both 
> an area (which is good for rendering/barriers/advanced routing) and 
> one or more highway=steps (which is good for routing + network 
> analysis + attaching to a building entrance) ways?

Yep. I think;
  the laterals should be tagged as steps - that way they can be used for 
routing and hand rails and number of steps.
the upper and lower ways should be tagged as footways - that way they 
can be used for routing .. and tactile paving..

This would aid routing as any connecting way to any of the ways - top, 
bottom or lateral should route.

------------------ Still thinking on it. Mixed feeling on the suggestion 
of providing a central way of steps .. the 2 sides would handle routing.
> On Thu, Mar 28, 2019, 8:06 PM Warin <61sundowner at gmail.com 
> <mailto:61sundowner at gmail.com>> wrote:
>     Hi,
>     This one has been sitting for a long while! Still not certain
>     about some
>     aspects of it.
>     See what you make of it.
>     https://wiki.openstreetmap.org/wiki/Proposed_features/Area-steps
>     Discussion here for preference.
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