[Tagging] Kerbs

[Nick Bolten]

> The question is: does it make sense to introduce another `kerb` value in
order to differentiate between standard high kerbs and very high kerbs at
public transport stops?

If I understand the question right, it really comes down to what you
consider to be a curb. Some transit stops have raised platforms, and there
is no expectation that an individual would ever traverse that displacement.
But if it could be reasonably expected that someone would walk across that
displacement, I think `kerb=raised` combined with `kerb:height` would
satisfactorily describe the situation, because I've always interpreted
`raised` to mean `square corner`. That seems to be how all the examples
are, and the iconography used in various presets all show a square corner.
Also, a `rolled` curb also has a significant change in height, so it would
be odd if `kerb=raised` just meant that the curb implied a displacement.

Regarding Matej's suggestion: I think that `kerb=normal` has the
disadvantage of being ambiguous, or at least geographically varying. A
normal curb in many American suburbs would be `rolled`, or rounded, while a
normal curb in many dense areas of cities would be flush (with bollards
protecting pedestrians from traffic).

With that said, I agree that there are opportunities for improving `kerb`
tags. Here are some ideas to toss around:

- `kerb=square` would seem to be as descriptive as `kerb=raised`, but more
clear.

- `barrier=kerb` is sometimes used in combination with `kerb=raised`, which
seems redundant to me.

- `kerb=raised|rolled|flush` describes a curb interface with very little
horizontal component (a few centimeters at most), while `kerb=lowered` is
used for describing curb/kerb ramps, which can be 1-2 meters long and have
surface properties.

That last point brings up another issue, which is the meaning of `kerb` in
different tagging situations: as an attribute of a node on a street (such
as in conjunction with `highway=crossing`), as an attribute of a node on a
footway (such as in conjunction with `footway=sidewalk`), and as an
attribute of the way itself (the curb along a sidewalk). `kerb` means
different something slightly different in each of those cases,
respectively: the crossing *has* curbs on each side, of certain forms,
there *is* a curb interface along the footway, and the footway *has* a curb
of some form on one side.

If you have the time, I'd also like to invite anyone to provide
`kerb`-focused feedback on the Talk page of the (draft) pedestrian network
schema page:
http://wiki.openstreetmap.org/wiki/Proposed_features/sidewalk_schema. Its
purpose is to help organize a set of tags to best describe the pedestrian
network, and the concerns that have already been raised would be very
useful in the "Proposals to be worked into separate RFCs" section.

On Thu, Dec 28, 2017 at 1:54 PM Selfish Seahorse <selfishseahorse at gmail.com>
wrote:

> I agree that `kerb:height` is more useful than `kerb`. However, `kerb`
> seems to be a good starting point when mapping many kerbs and you
> can't measure them all yet, as it gives a rough information whether
> most wheelchair users can cross the street there or not.
>
> The question is: does it make sense to introduce another `kerb` value
> in order to differentiate between standard high kerbs and very high
> kerbs at public transport stops? Or should common high kerbs be tagged
> `kerb=raised` as well? The explanations on the wiki are contradictory
> in that regard (e.g. 'older kerbs' vs 'raised above the norm').
>
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