Divided roads with intersections, without allowing u-turns?


I’m new to OpenStreetMap, and have taken the editing tutorial, and Googled to try to find an answer to this, but I can’t. Hopefully, it’s okay to ask this question here.

In this part of Perth, Wellington Road is divided by a barrier and drawn as two parallel one-way roads.


There’s an intersection with lights with Barrack Street.

As it’s currently drawn, OSM will route a person like this:

If I understand it correctly, the OSM map currently is interpreting the divided Wellington Road as two separate roads, and the intersection highlighted in the screen cap above as being a tiny piece of road that lets you drive safely to the second set of lights, and then back onto Wellington Road.

However, the intersection looks like this:

And so directing people to perform a U-turn at these lights is illegal. I’m not sure how to edit this map to have it understand this intersection correctly. I’d like to correct this intersection, and quite a few other intersections like it along Wellington Road. Is there anyone who can give me some advice?

Kind regards!

OSM doesn’t route! All routing is done by third party applications.

What is the basis for saying there are no U-turns? Is it a general rule for your country. In that case, you should request the various routing engine developers to add rules to their software.

Is it because there are explicit no U-turn signs? In that case, you should add turn restriction relations to prevent the U-turns.

Is it because, although there is no absolute law against it, it is likely to be viewed, by the police, as dangerous driving? That’s more difficult, as the decision will depend on heuristics. I suggest you define a set of heuristics, based on objective information about the roads, and suggest to the routing engine developer that they apply them.

The routers should be making their decisions on the same information as a flesh and blood driver would.

If it is illegal to turn at this point you need to add a turn restriction. I don’t think, though, iD has a built in support for this kind of restriction involving three ways. You can still manually do it.

Do you only use iD (as in your second screenshot) or do you also user another editor like JOSM?

You need to add a restriction like this https://www.openstreetmap.org/relation/7664317
(But not all routers support the restrictions when role “via” is a way, like this case)

Thanks hadw, we’re using graphhopper/jsprit. I’ll try making this an issue in their forum.

Many thanks! That’s what I was wanting to know. Thank you for showing me.


But can people make U-turn when Right turn is allowed by lights?