[Tagging] "width" on streets: Time for a recommendation

Supaplex supaplex at riseup.net
Tue Sep 29 09:38:54 UTC 2020

Now I am a little confused.

As I understand Pieter, you used "width:carriageway" in Bruges in a way
that includes parking:lanes (although you can estimate later how much is
effectively not available for flowing traffic if using parking:lanes).

My initiative for a clarification of the tagging was motivated among
other things to find a distinction between width /with/ and /without/
parking lanes in order to not only indirectly estimate the effective
width but to measure it directly. Personally, I had understood
"width:carriageway" to mean only the effective width available for
flowing traffic. But maybe this is exactly the right term for the
measurement from curb to curb and we still need a new term for the
effective width ("width:traffic_area")? Or is it anyway illusory to
specify the effective width of a roadway, because it has no "fixed
limit" (parking cars are changeable) and you can only estimate it anyway
by a combination with "parking:lane"...?

I think it would be helpful to be able to specify an effective width if
needed. After all, this is the most interesting parameter for assessing
the quality/usability of a street. Even with a full parking:lane-tagging
the estimation is worse than simply measuring it directly. For example,
in the case of "half_on_kerb" parking it is not clear to assume that
exactly half the average vehicle width is "lost" on the carriageway -
sometimes there is only one tire on the sidewalk and two thirds of the
vehicle occupies the roadway. Also global assumptions for the loss of
width when parking "diagonal" or "perpendicular" seem unrealistic to me.
De facto, parking lanes almost always occupy a constant area, and the
effective width of the carriageway can be specified to within a few
decimeters on site or on aerial photographs.

What do we do now? My (new) suggestion: "width:carriageway" means the
total road width from curb to curb or from edge to edge of the road
surface. "width:traffic_area" (or another suitable term; so far nothing
comparable is in use as far as I see) could be used to indicate the
effective width available for flowing traffic.


Am 27.09.20 um 22:47 schrieb Martin Koppenhoefer:
> sent from a phone
>> On 27. Sep 2020, at 13:45, Pieter Vander Vennet <pietervdvn at posteo.net> wrote:
>> This width was tagged with 'width:carriageway'. 
> I think this is a good tagging decision, being explicit about which width you have measured seems the way to avoid ambiguity. (and it still leaves room for the next project which could measure sidewalk widths ;-) ).
> Cheers Martin 
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