Double or single solid line


I saw that there have been some discussions before regarding this topic but I didn’t get what should be the best approach to have turn restriction when we have double or single solid line. There a many cases in which we don’t have signs or marks that indicate for example that you cannot turn left at the intersection but there is a double or single solid lane that means the same after all.

Thank you very much!

Suppose you’re talking about the divider tag on highway=* objects. Been tagging this for a while, seen at least one other removing them again, GKW, and testing in Valhalla, OSRM and GraphHopper giving it a week+grace on new roundabout where the flares end in solid divider lines on exit roads. It had no effect, the no-u–turns were needed, albeit no router would actually route that way but just in case someone stops on the exit realizing to have taken the wrong exit.

+1 for SekeRob. That is, at certain points where the road is a single way representing a single carriageway with two-way traffic, at points where a u-turn or left turn (rightsided traffic) could be made but there is a double divider line legally prohibiting that. I think the double line warrants a turn restriction at those points.

Where a road nears a roundabout and splits around a flare, the splitting point often has doube lines (no sign) to prevent a u-turn to reenter the roundabout. The tun restriction tells the route that traffic on the exit is not allowed to turn sharp left onto the approach lane. If the turn restriction is not there, the router has no way to know that the vehicle cannot turn sharp left there.

Surely such rules depend on the country you are discussing. You haven’t said that or have I missed it.


Not even just country, but sub-national polities too. E.g. in British Columbia it’s perfectly legal to turn left across a single or double solid yellow line. In neighbouring Alberta it’s legal to turn left across a single yellow line anywhere, but crossing a double yellow line is permitted only in a rural area; in urban areas, turning left across a double line is not legal, but it’s a rule that is often not enforced if it causes no disruption to traffic flow.


Yes, you all are right that depends on the country and even sub-regions. But I am willing to know what is the best approach to mark those cases in countries where we know for sure that a single or double solid line means no turn to the left, you cannot overpass that solid line…so it’s a turn restriction but without anything else displayed on the roadside, no sign, nothing…can we simply add a no_left_turn_restriction?
Thank you!

Where a marking on the road legally means no turning, you can add a turn restriction.

In places where a particular marking does not mean that turning is legally disallowed, you don’t add a turn restriction.

Is such a restriction really a thing though.

Many years of driving in France, where the rule exists, my observation is that where there is a solid line there are gaps in the line at every driveway/sideroad to allow turning.

Same in Nederland. When there is a gap at a turn in the dividing lines, drivers may turn, so no turn restriction there.

That’s no different here in Italy and from observing new asphalt stretches and the meticulous interruptions by dashed lines of the (water color paint quality) solid line dividers at entrances of service and driveways, it leaves little doubt that solid is solid, do not cross, do not u-turn.

Frankly, while I see the ‘you may do when safe’ logic, the solid and double solid is reasonably telling why they’re there, not for decoration, not only for informing that there’s your lane and the opposite way’s lane.

this is why it should be tagged when there isn’t. Quite often the solid line is interrupted to allow for turning into properties, but not always.

Not that long ago we had the same situation in Nederland. Nowaday the road construction rules require very precise lineage, including dashes for each and every serviceway and driveway, even rural private tracks.
If there is an interruption for entrance into a private field, additional signeage is required to prevent unwanted turning. That said, in practice you can find a lot of spots where the rules are seen as guidelines for others… so sometimes clear intent has to suffice (and that can hold up in court).

I think there is a misconception, when the line is not interrupted, you may not cross of course.

1 Like

Will obviously depend on local laws, but I would expect to be able to cross it to overtake a slow moving vehicle such as a tractor or bicycle, after obviously checking for enough visibility.

What would be the best solution for this case for example?
There is a double solid lane, but due to no restriction on that intersection, the routing engine will just use it in a bad manner. Thank you!

I’ve labeled highway dividers, aiming to prevent mistaken U-turns at exits despite router variances.

I would say that if the rules of the road in Riga are such that turning left from that service road across the double lines in the centre of Gustava Zemgala gatve is not a legal manoeuvre—if the rule would be no different than if there was a no-left-turn sign there—then it’s perfectly reasonable to add a no-left-turn restriction relation there. I would just be careful about mapping these sorts of things in jurisdictions you’re not sure about.