Thai road numbers

Discussion in 'Touring Northern Thailand - Trip Reports Forum' started by Jurgen, Sep 10, 2011.

  1. Jurgen

    Jurgen Moderator

    Oct 23, 2009
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    You don't need route 66, to get your kicks in Thailand; you would even not find a trail with that number (at least not yet).

    When I write reports for the GT-rider website, I often use, like other contributors, route numbers as esoteric shortcuts to describe itineraries. This is confusing for readers less familiar with the region, and I hope that this short post brings some clarification about the Thai roads numbering system.

    1. Road definitions.

    The official definitions of highways, in Thailand, are as follows (1992 Thai Highway Act):

    * Motorway (Special highway), a large capacity highway designed for high speed traffic, with limited access (responsibility of Department of Highways, DOH). Some existing highways have been upgraded to the new motorway network; others have still to be build.

    * National highway, the main roads (primary highways), part of the network connecting regions, provinces, districts, and other important destinations (responsibility of Department of Highways, DOH). They grant unrestricted access to users, mixing pedestrian, bicycles, agricultural traffic with racing vehicles, overloaded ten-wheelers, and even elephants.

    * Rural highway or rural road, highway under responsibility and registration Director General of Rural Highways (DORR). Here, even more, everything is possible, not only very slow traffic, but also drying harvest, spread out on the road.

    * Local highway or local road, highway under responsibility of local administrative organization (registration overseen by the provincial governor).

    * Concession highway, highway for which a legal government concession has been granted (registration is overseen by DOH).

    Another network is a sort of “overlay”:

    * Thai expressway system: high capacity, usually elevated and controlled-access highway, around Bangkok and nearby provinces (operated under the oversight of the Expressway Authority of Thailand (EXAT),

    2. The Big Four.

    Four famous national highways leave Bangkok toward all cardinal points and link the capital to the main provinces. They have well known given names and are the most important roads for each region :

    * Route 1: Phahonyothin Road. Northern Thailand - all the way up to Mae Sai, linked to the Tachilek bridge to Myanmar.

    * Route 2: Mittraohap Road ("Friendship Road"). Northeastern Thailand - in direction of Nong Khai, linked to the Friendship Bridge to Laos.

    * Route 3 : Sukhumvit Road. Eastern Thailand - already a major artery inside Bangkok, leading to Chonburi, and ending one hundred kilometers before Hat Lek crossing to Cambodia.

    * Route 4 : Phetkasem Road. Southern Thailand - down to Songkhla, linked to the Malaysian “North–South Expressway”.

    The “big one” (Phahonyothin Road) passes through Lampang, where a branch out, route 11, connects to Chiangmai. A huge kilometer marker indicates the distances to important destinations.


    3. First digit and region.

    Following the model of the “Big Four”, the first digit of a highway indicates which region is primarily deserved. These are the subdivisions:

    1. Northern Thailand
    2. Northeastern Thailand (Isan)
    3. Central, eastern Thailand and upper South
    4. Southern Thailand

    Thus, the first digit gives a general indication about the geographic context of a road.

    Additional numbers are made available to the new “motorway network”, making the situation less obvious in the future. Segments of route 7 and 9 already exist and the other decimals (5,6, 8 are allocated in the Motorway Master Plan.

    One day we might see a branch out called Thai “Route 66”; or even “Route 77” ;) !

    4. Number of digits

    The one digit roads are the main national highways, and additional digits should give an indication about the relative importance of the links. This is the official classification:

    * Two digits road: main highway (within a region)

    * Three digits road: secondary highway (within a region)

    * Four digits road: intra-province highway

    Unfortunately, the length of the number gives no clue about the traffic, the pavement and the size of the artery. Development of settlements, need for communication links and money flows for construction, do not always comply with the master plan’s forecast.

    Specialists argue about the incoherent numbering of the Thai highway network; many two digit links are as important as the “Big Four” and some three digit roads are dual carriage ways, with four well paved lanes.
    Bikers are lucky, the GT-rider website ( provides accurate descriptions of many itineraries, allowing them to savour the trails best suited to their mood and bike’s tyres.

    As an example, the North is rich in roads beginning with the digit “1”. The Big “One” (Phahonyothin Road) runs up from Bangkok to the Myanmar border in Mae Sai, deserving Lampang, Phayao and Chiangrai. It does not include Chiangmai, which is connected through route 11, a branch out, starting in Lampang. This city is, however, well deserved in all directions, by 3 and four digit roads.

    To make it less straightforward, some 4 digits roads have different initial numbers. This is probably the result of allocations by less centralized offices.

    A route 3037 is in the North:


    A route 4007 is in the North:


    A route 3011 is in the North-East:


    A route 4016 is in Loei (North-East):


    A route 6030 is in the North-East:


    Another particularity is the existence of roads with identical (four digits) numbers, in different locations. One example is the 1001, north of Chiangmai and route 1001 near Phayao

    Route 1001 in Phayao:


    5 The ultimate dream

    The brainchild of a cooperative project called “the Great Asian Highway” is an ultimate highway dream. The first fabulous link is running from Tokyo to Bulgaria, over a distanced of 20,557 km, half of the circumference of the earth. AH 1 (Asian Highway 1) also crosses Thailand, following existing segments of route 33, 32, 1 and 12, from Aranyaprathet, at the Cambodia’s border to Mae Sot, the frontier with Myanmar.

    Marginally less impressive is Asian Highway 2 (AH2), running on 13,177 km, from Denpasar (Bali) to Iran. This route can also be enjoyed in Thailand, from Sa Dao, Malaysia’s border to Mae Sai, the northern entrance to Myanmar. Its journey follows mostly route 4 and route 1.

    Asian Highway 3 (AH3) connects Russia to China and Myanmar (Burma). It has a planned length of 7'331 kilometers, from Ulan-Ude to destination, crossing into Thailand on the Mekong bridge, in Chiangkong (under construction). It joins route 1(AH2) in Chiangrai, to run to the Myanmar's border.

    AH3 near Chiangkong:


    AH3, is partly following route 1152, partly route 1020:


    Junction of AH1 and AH3 is in in Chiangrai:


    Six other, less prestigious but still interesting Asian highways, are crossing Thailand;

    AH12: Laos (on AH3) to Thailand (on AH1)
    AH13: Oudomxai, Laos (on AH12) to Nakhon Sawan, Thailand (on AH1/AH2)
    AH15: Vinh, Vietnam (on AH1) to Udon Thani, Thailand (on AH12)
    AH16: Dong Ha, Vietnam (on AH1) to Tak, Thailand (on AH1/AH2)
    AH18: Hat Yai, Thailand (on AH2) to Johor Bahru Causeway, Malaysia
    AH19: Nakhon Ratchasima, Thailand (on AH12) to Bangkok, Thailand (on AH2)

    The blue panels marking the Asian highways are symbols of a big adventure, a vision of unhindered horizons, a dream of travels without limits, without borders, an evocation of the sailing routes spanning the World. This is still far from reality, and few sectors are totally open, at least for bikers traveling on their two wheels.

    6. Anatomy of a milestone

    Road markers in Thailand are called « lak kilo » (kilometer stick). The word is the same in Lao language where many villages bear the name of a « kilometer marker » indicating the distance to an important city. In that country, settlements are called « Lak Sao » (kilometer twenty) or Lak Samesip Song (kilometer 32) or what ever distance it might be.

    A square house is the basic shape of a Thai milestone :


    Milestones, in Thailand, are square, with a triangular roof. The front has a relief picture of a Garuda bird (a Krut, the official King's sign), with the road number. The Thai letters « K » and « M » are written underneath with the distance to « point zero », the starting of the route. It is often a city, but can also be the intersection with another link. The back of the pillar in blank

    On the sides, the first distance is to the nearest village, and underneath, if different, to the next bigger agglomeration. Each side has generally one or two inscriptions, one of them usually similar to the distance written on the front panel. The exception is when “point zero” is not in a city. Then, the given distance, on the front, is to the starting point.

    Thai milestones are painted white, with black inscriptions. A new fashion is to renew them with preprinted reflective panels.

    A milestone with an identical distance on the side and on the front panel:


    A milestone with a shorter distance (to an intersection) on the front panel:


    The end of this route, as indicated on the fornt panel, is before the city:

    Not all milestones are informative:


    Some routes have additional distance markers between the milestones. Small pillars are planted every 200 meters, providing a precise localization on an itinerary.

    Small sticks divide the kilometer distance in 200 meters increments:


    Rural roads are indicated by large blue panels:


    Rural road signboard:


    A small rural road in Phayao:


    A new fashion is to use kilometer stones for marketing purposes. Fun pictures of large, big or huge kilometer markers are posted on GT-rider’s website, at the following url address:

    Threads with similar contents (there are probably more information of the same type to be found in the GTR-database):

    Thai Road numbers and markings

    Search on road numbers:



    WikiProject Thailand
    accessed 05.09.2011

    Thai highway network (from Wikipedia)
    accessed 05.09.2011

    Thai motorway network (from Wikipedia)
    accessed 05.09.2011
    accessed 05.09.2011

    Asian Highway Network (from Wikipedia)
    accessed 05.09.2011

    Pdf document describing the Asian Network
  2. Ryan Kuo

    Ryan Kuo New Member

    Apr 22, 2011
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    You are definitely the Thai Road expert!! But I doubt if I can just travel myself by follow your instructions. Better still to have you accompany!! :p
  3. SilverhawkUSA

    SilverhawkUSA Ol'Timer

    Mar 15, 2003
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    Excellent research project, Jurgin. You answered some lingering questions I have had. and I consider myself fairly well traveled. Some very nice photo compositions also. Thanks.
  4. cdrw

    cdrw Ol'Timer

    Oct 6, 2006
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    Jurgen...what an incredibly informative post!
    I admire your perseverance in compiling this dissection of the Thai road signs/markers.
    Thank you!

    I suggest that this post be transferred from the Northern Thailand forum and re-located as a 'stickie' on the General Discussion forum.
  5. speedybuffalo

    speedybuffalo Active Member

    Aug 13, 2009
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    super comprehensive explained principles - thanx Jürgen. Of course as a a pedantic rider I also fought my way through conflicting numbers. May be U have a valid explanation for that 2: Quite frequently i found the numbers on the blue road boards are not the same as on the white milestones on the same road .... :( (and 'of course' different to my most trusted ThinkNet maps).
  6. LivinLOS

    LivinLOS Ol'Timer

    Mar 11, 2008
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    Super post..

    Makes me laugh tho how many Rds they will use the same number for.. I know at least 3 or 4 '4s' down south..

    Surely a Rd cannot split in a Y and both branches (in fact all 3 of the Y) be the same number ?!?!
  7. Jurgen

    Jurgen Moderator

    Oct 23, 2009
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    Thank you friends for reading my post. I am not an expert but was puzzled by numbers and did some research … that might interest others.

    @ cdrw, yes you are right, it is not be the right place for the post. I (wrongly) put is there because the « sticky » giant-kilometers was there. I suggested to David to move it where ever suitable

    @ Speedybuffalo : you are probably referring to the blue « AH » panels. These are for the Asian highway network and, only by chance, in some cases similar. Usually they are different as it is a totally different numbering system. So yes, the blue panels are different from the milestones. The other blue panels are for rural roads (tanon chonabot), they have four digits and the milestones have the same numbers. It is possible that inconsistencies exist, but I have no examples of such differences. As you know the panels for the highways are white.

    @Ryan : do not hesitate to come over tho Thailand, roads are fabulous and you do not need a guide. Nevertheless, I will be happy to make a ride with you

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