Variable Reference Number

Thai reference numbers are often hard to understand for us Farangs. In Ubon Ratchathani province, I stumbled upon road which started as อบ.4069 on a Department of Rural Road sign. The kilometer stones showed the same number. Suddenly, a DRR sign showed up with อบ.4049, and then the kilometer stones also used that ref number. A few kilometers later, things reversed to อบ.4069.
I remember that somewhen later, a reference number changed midway (but did not reverse).
What does that mean? Are reference numbers somehow linked to the Amphoe also (not only to Changwat)?
I can see on Google Earth that the Northern part was not paved while the other parts were already paved when Google’s pictures were taken (no MapBox or Bing for that region available); further North, an unpaved dirt road connects (or likely: that tertiary is still not paved there yet). Could the numbers indicate different phases of construction / pavement?

I have seen some questionable numbering schemes here in Thailand but never anything like you describe. Maybe one of the Thai mappers can offer some help. In the meantime, I’ll just subscribe and follow.

I think the answer is probably quite simple … the DRR is renumbering many roads in Thailand, but they dont get round to changing both signs and milestones at the same time.
One favourite of mine (as I ride it regularly) is the short cut from Phu Ruea to Udon Thani…
For over a year, the sign said ลย.3002 while the milestones said ลย.2002.
Last November they finally got round to changing the sign !
And I often see milestones changed half way … I guess they are just half way through the job ! I tend to think if the road is changing, then go with the new number, and just add a note for other mappers.

Addendum - just noticed even I had only changed the western section. Now I have made it consistent along its length and will double check next time I ride it.

Though that looks like a reasonable explanation, that does not seem to apply here: the signs and milestones looked quite new.
And here it would imply a double renumbering: from อบ.4069 to อบ.4049, and then again from อบ.4049 to อบ.4069…

Most probably human error… as a recent visitor to Thailand observed, only in Thai would they let their road workers dress in camouflage gear !!

That’s a fact to be always considered…

Now I found the other example in Saraburi province:

These are different issues. The DRR’s numbering system is that the first digit indicates the level of highway a road connects to, while the other three digits are index numbers. So when a highway is upgraded or downgraded, the rural roads connecting to it have the first digit in their ref changed. This doesn’t explain the Ubon case in the OP though.

Okay, I’ve checked. The อบ.4049 case is obviously an error, since the real อบ.4049 branches off national Hwy 2172 at 14.9809, 105.2905 in Phibun Mangsahan District.

สบ.5052 appears to have been renamed สบ.1052 within the past few years. This is because it was extended to include the part of the Raphiphat Canal service road up to Phahonyothin Road (Hwy 1).

This means that this stretch of road should actually be part of สบ.1052 instead of ปท.3034. Bernhard, what were the sources you used for the recent ref addition?

That’s an interesting information. Can you explain that in further detail (perhaps also put it into the wiki)? I.e. what do those codes 1-6 mean (or even higher numbers, but 6 was the highest I can remember).
And I happened to see a three-digit number in Nakon Nayok: - well, that can be an error by the guys constructing the sign (I am sure that there were only 3 digits preceded by นย).

I travelled on bicycle thru Thailand (mainly Isaan), and on the way I stored some waypoints on my Garmin (typos not excluded, remember the ref 219 vs 2245 thread…).

The waypoints file (Garmin stores them separated from the “track”, I uploaded only the files with tracks; most of my waypoint notations are cryptic abbreviations) “Wegpunkte_27-DEZ-16.gpx” shows following waypoints:
25.7993642016-12-27T05:50:00ZSb 6046Flag, Blue
28.3186492016-12-27T06:04:21ZPt 3034Flag, Blue
29.0651052016-12-27T06:16:07ZSb 5052Flag, Blue

The “Pt 3034” is just a few meters after turning into that road from a road without number (possibly also Sb 6064, but I was not sure if that number is also valid after the turn to the left along the minor canal) from the other side of the big canal. You may download the “track” file from my traces ( file Track_2016_12_27_195854.gpx ). I cannot specify the exact source: a DRR sign or a kilometer stone.

For a cross-reference, can you check their database?

It’s not a suitable source to systematically get details from, but checking your questionable road could give some insight.
Website is horrible slow from outside Thailand, so can’t use it from here.

The Roadnet database covers only DOH roads. But I just found out that the published index of DRR roads are now available at (including past issues). The given starting-ending point coordinates seem quite unreliable, so it’s quite hard to decipher if you don’t read Thai.

However, by comparing the year-to-year changes, I was able to discern this much for สบ.1052/ปท.3034:

  • 2013: the stretch of road from Hwy 1 to the corner where สบ.5052 meets ปท.3034 is added to สบ.5052. Since it now connects to a 1-digit highway, สบ.5052 is renamed as สบ.1052.

  • 2015: that stretch of road is removed from สบ.1052 and added to ปท.3034 instead. However, the ref for สบ.1052 isn’t changed back, and ปท.3034 isn’t renamed.

So your addition is correct. I guess they changed it because it made more sense to have a single route running the length of the canal. It's had the side effect of having a PT road in Saraburi Province, though, in addition to the 1st-digit discrepancy.

Regarding the DRR numbering system, roads beginning with 1 connect to 1-digit DOH national highways, and likewise for 2, 3 and 4. DRR roads beginning with 5 connect to other DRR or local (municipal/PAO/SAO) roads, and roads beginning with 6 connect places without forming part of a larger network.

Aberrations such as the นย.004 mentioned are probably remnants from the old system before the DRR was established in 2002. If you see the words โยธาธิการ (ยธ.) or เร่งรัดพัฒนาชนบท (รพช.), those are old refs from the Public Works Department or the Office of Accelerated Rural Development.

Yeah, I should write this into the wiki.

Thanks a lot for your explanation, Paul! I guess we could learn some new aspects here.
Well, mapping reference numbers based on what we see on the ground will stay complicated…

Came along road อบ.4069 again last December. I did not see any sign with อบ.4049 any more. So that’s cleaned up on ground.