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Searched a lot for the steps involved in adding a roundabout. But was not able to locate a simple step by step tutorial .

The roundabout in question has two lanes and three exits .

I have traced the roads till the roundabout .

Please guide me how to add a two lane roundabout.



asked 12 Nov '11, 08:32

mjk6035's gravatar image

accept rate: 0%

You just have to draw a circle and apply the junction=roundabout tag as described on the roundabout wiki page and the traditional highway= tag as well (you should always use the highest highway classification of the roads leading to the roundabout). The number of lanes is described by the lanes= tag, in your case with lanes=2. The direction of the way you draw specifies the direction you have to drive through the roundabout (clockwise or counterclockwise). Adding exits and entries is simply done by connecting highways to the drawn circle. That's all.

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answered 12 Nov '11, 09:10

scai's gravatar image

scai ♦
accept rate: 23%


Thanks for the answer . Forgive if what I am asking is too basic .

With reference to scai's answer please clarify how to draw a circle . Do I have to put a groups of nodes in a circular format?

I am using Poltlatch-2 I tried adding a building and changing the tag 'junction=mini_roundabout'

Would be very helpful if you could be step by step instructions

Thanks in advance



(12 Nov '11, 12:39) mjk6035

Yes, you have to create nodes in a circle and connect them to create a circular way. Potlatch 1 has a shortcut T to arrange nodes on a closed selected way in a circle. I don't know if a similar shortcut exists for Potlatch 2.

edit: seems like Potlatch 2 has this little toolbox in the lower right corner which you can use to arrange the nodes of a created way in a circle.

(12 Nov '11, 13:27) scai ♦


Thanks for replying . Based on scai's suggestion I have been able to draw a roundabout


Please check and let me now if it is ok.



(13 Nov '11, 07:08) mjk6035

Looks good, Mathew, except for the missing connections of the entry/exit roads. You have to connect them with the roundabout's highway (by using the same nodes twice) or else routing programs won't be able to use them correctly. Also you don't have to apply the oneway= tag as roundabouts are always oneway. Just draw the line of the circle in the correct direction or reverse the way if you draw it the opposite way.

(13 Nov '11, 08:40) scai ♦

hi thanks for your reply . I could not identify which connections of entry/exit roads are missing . The roundabouts first exit road is not complete .Hopefully I will be able to complete that soon


Thanks in advance



(13 Nov '11, 11:50) mjk6035

I fixed the missing connections for you (and also removed the oneway tag). There is also a question about the most common mapping mistakes explaining the issue with unconnected ways . You should take a look at it if you want to learn how to spot and correct them.

(13 Nov '11, 12:25) scai ♦


Thanks for fixing the errors . To be frank I did not understand exactly what the mistake was . I went through the link http://help.openstreetmap.org/questions/1022/what-are-the-most-common-mapping-mistakes-that-other-users-make/1023

and got an idea of the common mistakes that are made.

Thanks in advance



(13 Nov '11, 12:38) mjk6035

Great! Note: when replying please create a comment instead of an answer, this is not a forum :).

(13 Nov '11, 13:46) scai ♦

@scai: you don't need to add the one-way tag to a roundabout, but it wom't do any harm, if one does, anyway, does it?

(14 Nov '11, 07:46) moszkva ter

No, it shoudn't moszkva-ter. But the way was drawn in the wrong direction and had oneway=-1 to reverse it again. I thought I better fix this because it might not be supported by all routing engines.

(14 Nov '11, 08:06) scai ♦
showing 5 of 12 show 7 more comments

There is a road that needs to be connected :) You can see it on the areal picture in Potlatch 2

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answered 08 Feb '13, 15:21

robvr's gravatar image

accept rate: 0%

Indeed there is - although interestingly it seems to date from after this question was asked!

(08 Feb '13, 16:07) SomeoneElse ♦
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question asked: 12 Nov '11, 08:32

question was seen: 10,309 times

last updated: 08 Feb '13, 16:07

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