Modifying a highway to a dual-carriageway in the city: Pattani

While mapping in the city Pattani, TH, we have observed that a portion of a primary highway “Ref=42” was mapped as a single road instead of a dual-carriageway from to for a length of approx 10kms.

But when Referring to the available Karta Image at this location we can see a physical barrier on the ground which needs to be mapped as a dual carriageway.

And also we observed that this highway has an incomplete relation which consists of “route 42” for a length of 172 km in total. We request your help to help us understand and fix the data at this location without affecting the relation and looking forward to your suggestion for a complete route for Ref=42.



Many highways are being changed from “common” highways to dual-carriage highways. Simple concrete borders for separating the carriageways are often not visible in the imagery, and can rather easily be placed on existing 4-lane highways. So when you detect such a carriageway separation on ground, just add the data to the database. If possible, also add U-turns.
As for the relation, I’d suggest to just delete it - I hope other mappers agree with that suggestion.

What’s the initial intended purpose of that kind of relation anyways? I’ve seen those in Malaysia too, and my itchy hands are forever tempted to delete them. :smiley:

To cause trouble? E.g. adding a lot of tags to the relation which - depending on the renderer - will overwrite tags on the way… (happened with Phetkasem road, highway 4: relation had highway=trunk, though that road is still not a trunk for some sections…)
No, seriously, I do not know.
It makes visualization of a long road easier, but so what?

Please fix the dual-carriageway, as others suggested.
We had a related discussion in the past. Roads like on your above picture, just without the divider in the middle exist in a lot of places. As software frequently assumes that you can start driving in any direction, if the road is mapped as a single way, this did lead to unsuitable route guidance suggesting to cross the road. In practical this is not allowed and often not possible due to traffic, but people still frequently do it and also create frequently accidents by doing so.

I would have suggested to also map roads which are clearly meant to be one-ways as two separate roads. even in case the divider is just a meter a of zebra paint. But this is a different story.

Regarding route relations. Try to keep them in order.

See the wiki:

they are quite common. Their use is sometimes disputed, as it is adding extra effort to keep them updated. But this holds true for most relations and some editors are known for making it easy to break them.

Specifically route=road are used to identify road segments belonging together even in case their ref is not unique in the area you are looking at.

Thank you everyone for chiming in. We will take the pointers and will modify this road into a dual carriageway. As soon as it’s modified, we will post the changsets for reference here. Thank you for sharing the resources Stephan!