Dual carriageway/divided highway turn in wrong direction
  • Hi - a bit of advice on OSM features, please. I've searched the forum but haven't uncovered the answer to this problem. A pointer to an existing thread would be welcome, of course. The description following is for driving on the left, in New Zealand, and is in British English.

    There's a junction I should be making a right turn at, a major intersection on a dual carriageway. But Mapfactor Navigator Free with Open Street Map plots a left turn to a junction further along the road where it asks for a U-turn. The traffic-light controlled junction in question is where a secondary road crosses a trunk road which is a dual carriageway. It seems that MFN does not know that a right turn is possible on the far side of the dual carriageway, instead preferring a left turn with the flow of traffic on the first carriageway before a U-turn to join the other carriageway. 

    What data should be on the OSM map to help MFN compute a right turn? (Assuming the problem lies in the map data rather than MFN, of course.)

    Hopefully this link will take you to the junction in question - https://www.openstreetmap.org/edit?editor=id#map=20/-37.66556/176.18706 My route is from the road to the north, making a turn to the west on the trunk road.

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  • This small connecting road is mapped as "unclassified". This type of classification MFN only routes for "last mile" if no other way is possible as standard for car. For me thats a bug as discussed further, because unclassified is the lowest kind of settlement connecting roads in OSM. But in this case I would give that part of road the classification of the road incoming to that junction. I will check and try later from my PC. I answered by smartphone.

    I guess that's wrong and one may drive from North into both lines of the dual carriageway. So I splitted the southward unclassified at the node, where it crosses the southern line of the dual c. and changed the new small part between the oneways to highway=secondary. The changing will be active in MFN free after map-update next month.

    Greetings from the other side of the World Germany

  • Thanks for the explanation, that's really helpful. And for making the change, too! 

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