Defining classifications below trunk


Soemthing like that.

I’d prefer to add some more description regarding the meaning / importance of each classification level.

True, most wiki pages on primary just say that primaries are subject to the central/national administration, while secondarires/tertiaries are subject to regional/provincial administzration. Only the German page on primaries notes that other roads which are important are also primaries; and a feature stated there is a vast number of vehicles using the raod (more than 10,000 a day).

Let’s add for primaries:

  • built for long-distance travel, typically beyond province borders
  • 2 or more lanes, wide enough for two vehicles to pass each other without reducing speed
  • often extra lanes on the side (“shoulder” ?), comfortably wide for bicycels and motorcycles
  • paved (asphalt or concrete)

For secondaries:

  • major roads inside a province
  • 2 lanes
  • paved (asphalt or concrete)

For tertiaries:

  • connect two or more villages/hamlets
  • often narrow
  • most of them paved, but unpaved roads are possible

I guess that could agree well with your numbering scheme in most cases - and for the remaining cases, we’ll have a description why we do something different.


Seems okay. We may need a separate guideline for urban roads, since the considerations there are rather different.

I’ve updated the wiki page ( Please take a look at the wording there, and correct it or refine it.

I think 4 digit roads need an extra hint. It is the most “inconsistent” type of roads, because freshly built roads typically get a 4digit number, regardless of their importance and physical features. In rare cases, they meet trunk standards (4015 south east of Nakhon Sri Thammarat, or 4047 east of Phattalung), and sometimes they are just provincial roads of low importance (i.e. tertiary). I’d like to add a “warning” to that section, that a conclusion from 4digits to “secondary” is not very reliable.

In case of the “blue sign” 4digit raods, I’d like to emphasize that the two Thai letters for the provincial code are part of the reference number and must not be omitted - better add “xx” as provincial code when you cannot write it than omitting it completey.

I wholly agree. I’ve come across a lot of rural highways that have their letter prefixes missing. This is one thing that will have to be manually checked when converting highways to follow the new guidelines. Some of them are identifiable by their having the “wrong” first digit for the region.


Updated the wiki page. Please look at it, and correct/refine it.


On this topic I’d like to discuss exactly how to add those two-character abbreviations. Current practice seems to include the “.” following the abbreviation and before the number part of the ref. But sometimes there is a space following the “.” Sometimes not.

I’m guilty of not adding the “.” in the refs for some tertiary roads I’ve mapped. I never could see the reasoning behind this and still don’t, except that the signage does include it. It only indicates an obvious abbreviation after all. My reluctance stemmed from my assumption that searching for a route number that has no spaces delimiting it from the two-character province abbreviation would be difficult. However, if the dot must be there in order to correspond with the signage, then should there be a space between the province code and the route number?

So my question is, should we include a space between the “.” and the route number?

I’ve started to edit the tertiary roads in my neighborhood that have no included “.” but would like this issue clarified before continuing.


I always tagged it the same way than on the sign. 2-character province, then a dot, then the 4-digit number.

Having a space instead the dot does not make it wrong, does it?
I personally just followed the writing on the sign so it might be easier for people to recognize. And hopefully the people DORR thought a bit before deciding to add a dot on each sign they produce. So it must be the correct way of spelling it.

Any input from our native speakers?


I never noticed if the signage included a space after the dot. This somewhat-official-looking list seems to suggest that the DRR prefers the format “นบ.3021” (without a space).

Having spaces after full stops/periods is a general typographic convention (with lots of exceptions).

I don’t think it’s critically important for readability either way although I tend to prefer including a space regardless of how the signage presents it. I am really only looking for consensus about how to do it in the future.

By the way, while we’re on the topic, the tertiary roads whose numbers begin with “1” generally do not have a province prefix and as I understand it, are “national” or interprovince roads. Are there cases where that’s not true? The numbering system is a bit convoluted because there is an example in the Wiki where there is a 4-digit number, in this case, 3278 which is a secondary highway beginning with “3” and no province prefix.



Consensus is important …I have been using the two letter Thai abbreviation, followed by a space, then the 4 digit road number.
Until now I have been cut & pasting from the site
I hope the Province abbreviations are the same as the DRR are using !

I am in agreement with adding a dot/period/full stop after the Province abbreviation, by my vote goes to omitting the space… not that it matters, but it allows for a marginally conciser display on the renderer and GPS.

Stephan - is there any way you can work your miracles and bring them all into line in one fell swoop, perhaps putting XX where a abbreviation does not exist. … which in turn could generate an exception list which we cud quickly correct.

Finally, that looks like a pretty useful document that Paul has provided a link to … as its in Thai I cant read it, and is it also copyrighted ? One bit looks like it might provide official start & end coordinates of the Rural Rds, which wud be very useful !

Rgds, Russ.

I can’t add the “xx.” where needed, but I can update the refs so they all follow the same standard. But what should the standard be?

a) xx.1234 (dot)
b) xx. 1234 (dot-space)
c) xx 1234 (space)
d) xx1234 (no dot, no space)
e) something else?

I personally vote for (a) for these reasons:

  • It is currently used the most
  • It is what is described in the wiki
  • It is what is used by other maps in Thailand:
  • It seems to be the standard in at least one official looking document (Paul_012)

I don’t think it is hugely important what we choose as long as we can agree on something - if needed we can change the standard in the future, though it will be more confusing for people not following these discussions.

Hi Russ and Johnny,

are you saying that all 4-digit roads are actually maintained by the Department or Rural Roads?
I thought that only those with the code are done by them, while there exist other 4-digit highways which are maintained by the department of highways.

So either way I see no sense in adding a XX. in front of them. What would this help? In case something is missing it is easier to spot it missing if it’s actually missing.
And in case we can’t distinguish, we shouldn’t change it automated.


I personally vote for (c)

A period is never seen in signs for an abbreviation in the US (and I’m guessing most other countries either), on road signs or postal addresses. It’s completely redundant and adds a character that takes extra space to display. I realize this is Thailand we’re talking about but I just wanted to add my 2 cents to the discussion.

Hi Stephan,

Absolutely not, I am saying I can’t do that. The reason being that there is no way for me to tell whether it is a 1234 for xx.1234 road. What I am offering is to make the roads that already have an been correctly marked as DRR consistent.

Option (b) has one more character than option (a) which you are arguing against. I think you mean option (c) which is just a space or (d) which has nothing?

OK, I did some further research and the Department of Rural Roads which names the roads uses option (a) as well:

If these really are the official names of the road, isn’t that what we should use?