Numbering on minor roads

Mapping around Chiang Mai I see that quite a few unclassified roads have been upgraded to tertiary and the number had XX. prepended to the road number. I understand that there could be province abbreviations in front of the numbers, but XX. doesn’t make sense. What am I missing here?

Perhaps the mapper who added "XX. " cannot type the Thai characters of the provincial code?

I have noticed this too.
IMO it would have been better to leave the Ref as 3012 e.g. as XX means nothing.
There are also others such as CHM.4335 and KHM.3013
Is there some kind of agreed standard here?
Most of the roads around CM just have their number as the reference.

CHM = Chiang Mai. As far as I know, there are at least two levels of numbered roads in Thailand: national roads and district roads. I have also seen rural roads with numbers and local roads.

I guess most mappers are in the same boat as me: I can read the numbers, but not the characters, so I can’t map them.

I think that a road “1234” without a provincial code is different from a road “NS. 1234”, isn’t it?
During my last holiday in the South, I saw many roads with 4 digits without code, and all of them started with a “4”. In contrast, roads with a provincial code could start with different digits also; often there was a sign reading “Department of Rural Roads” with the name of the province.
Consequently, I think that those roads should be mapped at a different level than roads with 4 digits without provincial code.

I think your observations are correct. If you look on Google Earth or Maps sometimes these roads are labelled ‘National Highway 1234’. So, since the xx. doesn’t seem to be a representation of reality, I will remove it where I encounter it.

I have stated in a previous post and I repeat it here that I don’t find it useful to blindly map road classes according to numbers, unless we want to create an administrative map of the world or Thailand, which not that many people will find useful. The infamous ‘kink’ in h’way 1 is my favourite example. With that in mind I will continue to map tertiary and unclassified roads not so much based on whether or not they have a number, but the importance, size and traffic volume. It’s not a hard and fast rule, I use my judgement based on the information I have. It’s sad to then see somebody ‘upgrade’ these minor roads, possibly without having been there.

Yes, there are national and provincial highways with four-digit numbers. The provincial highway numbers starts with the two-Thai-letter abbreviation of the province. E.g. “ขก.” for the province ขอนแก่น (Khon Kaen). See WikiProject Thailand and the referenced Wikipedia articles.

What do you mean with different level? Different class? I mapped already about 400 of these roads. And yes, I was there, not only to get the highway number. Both, the four-digit national highways as well as the rural highways serve the same purpose for the highway grid, i.e. intra-province connections. Thus it does make sense to have them in the same class. For the user the fact that they are built and maintained by different organizations doesn’t make a difference. Also for privately built or operated highways I didn’t see different classes anywhere.

Did I understand this correct? You are deleting the two-Thai-letter prefix of the provincial highways wherever you find them. This is the same as removing the prefix “A” from a “Autobahn”, the “B” from a “Bundesstraße” and the “L” from a “Landstraße” in Germany. Guess I got you wrong. Please explain.

By the way: Google maps of Thailand are grab. Especially in regard to highway classfication. There are just 2 line styles: yellow for one-, two- and three-digit highways and white for all other. Thus e.g. for four-digit highways and the driveways to private houses on private land have the same style.

No, I only remove the xx., not any of the Thai or other abbreviations, since I do understand that they represent something (even if I can’t read it, but that’s my problem).

I know what you mean about GM, but in a few places they seem to be not too bad with some residential streets named. In many places, however, GM is just plain wrong, showing lines where there isn’t even a walking track.

I think it’s no good idea to remove the “xx.” It indicates at least that this is a provincial highway. Thus not wrong but incomplete as many things in OSM. Without “xx.” the number is wrong. It looks like a national highway and can’t be distinguished any more from one with the same four digits.

See also my meesage “From formal criteria to usability” (
But I think that changing the “meaning” of tertiary, unclassified etc. is the wrong way - it was decided to be formal, as with most other countries - and I can tell you several examples from Germany where these formal criteria do not reflect the usability of the road either.
There are more tags available for roads than the formal classification only. Think of surface, smoothness, tracktype, oneway, lanes, etc.
I tried to create a map relying more on those criteria. I find it better than current representations, but I am not yet content with it. Though between Phangnga and Thapphut, highway 415 (a dual carriage way) is shown as a more important road than highway 4 (a narrow winding road), many “minor” oneway roads in villages show now up like trunk roads… I could not solve that issue yet, also a question to the mkgmap development list brought no answer.

Do you have a definition for useability which is valid for all users? I think that’s impossible. Different users have quite different ways to use or look at a highway. There are e.g. passenger car drivers, truck drivers, bus drivers, motor bikers, pedestrians, bicyclists, slow moving people, fast moving people, people with disabilities.

Thus I think it’s the only and the best way to describe the highways with criterias which are as far as possible formal and objective but still useable. From this data each user can create his map. E.g. there’s a MTB Map where MTB specific and other tags are represented in the line style. For routing higher classified roads are avoided and minor paved roads preferred.