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What is the the best/accepted way to map an intersection where a road changes from divided to non-divided at the intersection if the intersecting road is also divided? i.e:


I ask because I think this is the cause of stupid GPS directions at times "make a left, followed by a slight right"

asked 10 Jul '10, 21:19

Chris%20Dombroski's gravatar image

Chris Dombroski
accept rate: 0%


For most "advanced" mapping questions, a single best/accepted way of mapping doesn't exist, and mappers will therefore want to voice and discuss contradicting opinions on the topic.

I'm not aware of a consensus on mapping the style of intersections you describe, so this is probably one of those topics.

Please use the traditional forum or mailing lists for questions that will likely lead to discussion.

(10 Jul '10, 21:56) Tordanik

Right or wrong, I map that awkward situation like this:

__|__ |
  |  \|__
  |   |

In between the carriageways of the intersecting road, I gradually taper down the ways of the divided road to a single point where I then start the non-divided section. I start the slanting or tapering at the first crossroad and end at the single point at the second crossroad.

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answered 04 Sep '14, 07:25

wambag's gravatar image

accept rate: 0%

I have seen this method used in practice. The resulting driving directions can be a little ... odd, but it is often the closest to what is on the ground. It may help to try pulling the two leftmost nodes as close as could be considered realistic to minimise the "sharp bend".

(06 Oct '14, 22:49) InsertUser

It's not a style of intersection that is very common in the UK where I do most of my mapping but I think you would pretty much have to continue both carriageways to the far carriageway of the crossing road and then start the single carriageway road from there. So something like this:

  |  |
  |  +----
  |  |

Yes that may then need careful handling when doing driving directions, but so do lots of other things as well.

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answered 11 Jul '10, 09:00

TomH's gravatar image

TomH ♦♦
accept rate: 20%

edited 11 Jul '10, 09:01

normally its easy to handle which navigation software. one way with ref tag and implied oneway=no seperates to two ways with ref tag and oneway=yes. no other possibilitys.

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answered 04 Nov '11, 12:42

B%C3%BCrste's gravatar image

accept rate: 0%

an simple crossing with seperated right turn lanes, this is how I do it.

(04 Nov '11, 12:45) Bürste

@Bürste: It looks more realistic than a simple crossing, but it is inaccurate. If followed your map, cars turning left would pass on different sides (see

(04 Nov '11, 14:46) LM_1

your comment dragging down this discussion on maillist level.

it was actually some years ago fully normally to drive like this. they changed the rules here to allow more traffic. but as we are talking about a virtual path on a platform this abstract representation is perfectly what we want to teach our computers.

(04 Nov '11, 14:54) Bürste

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question asked: 10 Jul '10, 21:19

question was seen: 11,166 times

last updated: 06 Oct '14, 22:49

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