Talk:Proposed features/U-turn

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Difference to turn restrictions

I can't really see the advantage of your proposed tag over the existing turn restrictions, i.e. restriction=no_u_turn. See Relation:restriction Could you clarify that? --Mueschel (talk) 09:57, 16 November 2019 (UTC)

No u turn restriction is used to forbid U-turning at a node (normally a junction). My proposal is used to allow / forbid U-turning outside a node, directly on a way. Imagine the highway is 5 km straight with no junction, which is mapped as a simple straight line. You want to allow / forbid U-turn on the 5-km long highway. The relation can't do that. -Miklcct (talk) 12:37, 16 November 2019 (UTC)

Can be useful for routing software at start/stop points

Currently I know no OSM tag for a bidirectional way to designate a legal restriction to cross a special road marking (a double line, an island, ..) dividing forward lanes and backward lanes. So when routing software starts a trip at the middle of the way it freely selects forward or backward direction which is prohibited for a regular (non-special) vehicle in reality. When the trip should be ended at the opposite site of the way routing software has no info to prohibit a regular (non-special) vehicle from the left (right at the left driving counties) turn at the middle of the way.

This is true on all modes, applies to bikes and pedestrians too. If starting from a side road, turns are usually allowed across double solid white/yellow lines. ---- Kovposch (talk) 06:23, 11 August 2021 (UTC)

Is this actually useful?

Is this something that actually varies on a small scale? To take your 5-km highway as an example, are there actual stretches of highway where you can't deduce the legality of a U-turn based on the road classification ("no U-turns on motorways") and/or road geometry ("no U-turns within 100 meters of a curve")? --Carnildo (talk) 19:00, 19 November 2019 (UTC)

It certainly is useful. A very common situation, which is rarely correctly mapped, is a bi-directional two-lane road with a solid white line in the middle. This certainly is a clear u-turn=no situation in most countries. --voschix (talk) 13:17, 9 April 2021 (UTC)
Should you add country defaults to change=no though? ---- Kovposch (talk) 06:19, 11 August 2021 (UTC)
I agree that it is useful. I was just trying to find how to add this. In my situation a sign that says no u-turns for 570 yds, most of which is dual carriageway so restrictions can be added in the usual way but the last 70 yards is a bi-directional, two-lane road with a broken white line, i.e. you can overtake on the opposite side of the road but you still cannot u-turn. It also happens to be a very wide stretch of road so it would be physically easy. TrekClimbing (talk) 20:51, 10 August 2021 (UTC)
Would be easier to allow restriction=no_u_turn on way. 2235 instances.
---- Kovposch (talk) 06:15, 11 August 2021 (UTC)