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I have been doing a lot of mapping of Thailand recently, and the country has many roads that are separated by an impassable median. I am assuming that any road where the median is physically impassable (such as having armco/concrete barrier, hedges, or even grassed areas) should be drawn as two parallel ways (with one way tags usually). Conversley, any road where the divide can be physically (even if illegally) crossed, such as a white line, even if double & continuous, then it is to be drawn as a single way. Does that fit with OSM convention ? Russ

asked 17 Apr '11, 20:07

Russ%20McD's gravatar image

Russ McD
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edited 27 Feb '12, 20:54

Kozuch's gravatar image


Yes, it does.

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answered 17 Apr '11, 20:13

Richard's gravatar image

Richard ♦
accept rate: 18%


Don't forget to add all kinds of turn restrictions though: on a four way crossing you will need four no left turns and two no straights. This requires lots of cutting ways, too. Cumbersome...

(27 Feb '12, 16:57) moszkva ter

In Openstreetmap only a physical barrier (or a patch of grass) between the lanes makes it necessary to map it as two ways.

So yes that's the convention in Openstretmap.

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answered 27 Feb '12, 14:32

emj's gravatar image

accept rate: 15%

edited 27 Feb '12, 14:46


There's a section on this old wiki page: Editing Standards and Conventions#Divided highways

And here's an example of an awkward road in London which has a barrier in the middle down some of its length.

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answered 27 Feb '12, 15:42

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Harry Wood
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question asked: 17 Apr '11, 20:07

question was seen: 8,336 times

last updated: 27 Feb '12, 20:54

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