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E.g. Gamlebrua is a bridge that is physically limited to 200 cm width. Passing it with a 2m wide vehicle is legal, but my guess is that most GPS users would prefer an alternative route.

How should I mark up that? Marking it as 'cars not allowed' would be useful, but not entirely true.

asked 04 Aug '16, 10:39

Styrheim's gravatar image

accept rate: 0%

edited 04 Aug '16, 18:54

aseerel4c26's gravatar image

aseerel4c26 ♦

Use maxwidth=2 if this is the legal limit.

Usually we tag the legal state as well as the physical state of the road (surface, smoothness, tracktype, maxspeed, maxspeed:practical, maxheight, maxweight and so on). We don't tag "suggestions" like "avoid the road if possible", this is the task of the routing engine.

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answered 04 Aug '16, 10:51

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scai ♦
accept rate: 23%

edited 07 Aug '16, 15:57


Wait, OP didn't confirm that there is a legal max width. We can only put maxwidth=200 if there is a sign, right? In case of just a practical limit, then it should be maxwidth:physical= or just width= if I understand the wiki correctly. For that matter, I don't see why we would need the new and seldom used maxwidth:physical= when we already have width=.

(05 Aug '16, 08:53) joost schouppe

You are right. If there is no legal limit then maxwidth is wrong and should not be used.

Regarding width and maxwidth:physical: This is a good question and the wiki description is not clear. In my opinion width specifies the width of the road/path. This is equal to the maximum possible track width of the vehicle passing this road. However the vehicle itself could be somewhat larger. Imagine a road being 2 meters width, thus allowing only vehicles with a track width of 2 meters. Still it could allow vehicles with an actual width of 2.2 meters to pass. In this case one could use the tags width=2 and maxwitdh:physical=2.2. But that's just a guess, not sure if this would be really correct. This is better asked in a separate question.

(05 Aug '16, 09:59) scai ♦

@scai: I would think of maxwidth:pysical of the maximal width a vehicle could have. width is the width of the feature. In case of a bridge that may be significantly more due to construction elements/cage. Or is width on a typical bridge object in OSM the "track width" as you reason? I think it is not clear. What is the extent of width for that bridge picture? maxwidth:physical seems to be more clear to me. Full disclosure: I created that wiki page of a not yet widely used tag … as I just noticed. ;-)

(05 Aug '16, 22:38) aseerel4c26 ♦

@aseerel4c26 That's what I tried (and maybe failed) to explain. Yes, in my opinion width is the same as the track width of a vehicle since a vehicle can't drive on a road that is smaller than it's track width. For the bridge in your picture maxwidth:physical is IHMO a few centimeters larger than width.

(06 Aug '16, 09:38) scai ♦

@scai: thanks. And the track width is the outside width of the track/tires?

I think width is quite undefined what it means if tagged to a bridge. Which is the feature, which is described by width? Is it highway=unclassified (for example) or is it the whole highway=unclassified + bridge=yes?

In the past, when I tagged width onto a highway=residential I measured the width of the road, from curb to curb. If that is right – I do not know. What if sidewalk=both is tagged, too?

(06 Aug '16, 17:20) aseerel4c26 ♦

@@aseerel4c26 Yes, track width is the distance between the vehicle's tyres. But I think it is usually calculated based on the wheel's center which makes it a little more awkward.

If a road has a width tag and also sidewalk tags then in my opinion the width just applies to the actual road and not to the sidewalk. The sidewalk's width must be tagged separately using sidewalk:width or sidewalk:left:width + sidewalk:right:width. So measuring a road's width from curb to curb sounds right.

(07 Aug '16, 09:58) scai ♦
showing 5 of 6 show 1 more comments

You could use maxwidth together with maxwidth:physical to make clear that even if you accept to act illegal (or are an emergency vehicle driver or …) there is no way through this bridge with a 2.4m wide vehicle.

I guess the bridge is physically at least some centimetres wider than the legal restriction. So, maybe this:

  • maxwidth=2
  • maxwidth:physical=2.05
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answered 04 Aug '16, 18:56

aseerel4c26's gravatar image

aseerel4c26 ♦
accept rate: 18%

edited 05 Aug '16, 19:52

In that case use the maxwidth tag. There is almost no road that "should be avoided". Just add enough detailed tags and information so that someone can know if it's useable for their use case.

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answered 04 Aug '16, 12:16

rorym's gravatar image

accept rate: 11%

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question asked: 04 Aug '16, 10:39

question was seen: 2,520 times

last updated: 07 Aug '16, 15:57

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum