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Take a look at relation 2732863. I added the turn restriction but do not completely understand how it works despite reading all the available help I could find.

The restriction is only_right_turn when approaching the intersection from the south. The way forward (north) is blocked by a barrier and the road you're turning onto is one way going east to west. However, if coming from the north the restriction changes to only_right_turn. The same barrier is there to block southerly travel and the same east-west, one-way road forces the right turn.

Therefore the same intersection has two distinct turn restrictions depending on the direction of approach. But how does one specify that?

In the wiki I read about From: and To: members of a relation but can't figure out how to assign those roles to the ways in my turn restriction dialog in either Potlatch or JOSM.

asked 31 Jan '13, 16:32

AlaskaDave's gravatar image

accept rate: 16%

edited 01 Feb '13, 09:25

scai's gravatar image

scai ♦

You'll have to split Tha Phae Road at the intersection node and create two separate turn restriction relations. The one for the south approach (only_left_turn) would have the southward road (Kamphaeng Din), the intersection node and the westward Tha Phae Road as relation members. Kamphaeng Din Road will have the "from" role, the intersection node the "via" role, and the westward road the "to" role.

Conversely, the north approach will have an only_right_turn relation, with Ratchawong Road having the "from" role. The intersection node and the westward Tha Phae Road will thus be members of both relations.

permanent link

answered 31 Jan '13, 17:01

Paul_012's gravatar image

accept rate: 33%

edited 31 Jan '13, 17:06


Or, looking at Bing, you could split the northern way to have oneway slip roads into and out of it, and the road from the south then won't join the way to the north and everything will be controlled by the oneway sections and not need any turn restriction relations.

(31 Jan '13, 17:55) EdLoach ♦

@EdLoach - that sounds like a good and easy fix for this particular intersection. But I want to learn how to do this for the more general cases I'm likely to encounter in the future.

@Paul - okay, fine. So how do I assign those roles? The Potlatch advanced Turn Restriction dialogs are confusing to say the least and JOSM isn't much better.

Thanks for your time.

(01 Feb '13, 01:16) AlaskaDave

If anything on those pages is not clear, please tell us what that is, so they can be improved.

(01 Feb '13, 06:37) cartinus

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question asked: 31 Jan '13, 16:32

question was seen: 3,305 times

last updated: 01 Feb '13, 09:25

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