New speed limit laws

Hi. I know I haven’t been around lately, but I wanted to drop by to mention, in case you haven’t noticed, that a new default speed limit law came into effect 22 July.

It replaces the old speed limit laws in place since 1979 and 1981. Mainly, it adds new speed limits for several road categories: dual carriageways in non-urban areas, frontage roads, and the expressway. It also adds provisions for small four-wheeled trucks, big bikes, school buses, and tractors.

Another law from earlier last year also allows for authorities to designate certain highways that are dual carriageways with median barriers and no at-grade u-turns with a higher speed limit, that of 120 km/h for cars. So far this has been applied to Highway 32 up to Sing Buri and segments of a few others.

Here’s an overview table showing the default maximum speed limits set by the new laws as well as existing ones for the motorways and rural roads under the DRR.

The maximum limit for trailers/tuk-tuks was reduced from 60 to 55 km/h. Other than that, the numbers from the old law haven’t been changed, but some definitions have. Buses are specified as vehicles carrying over 15 passengers. The definition for trucks changed the gross weight from 1,200 to 2,200 kg. Trailers are clarified to cover both truck and car trailers. (The old law had some confusing wording where the trailer category actually only applied to car trailers and not trucks, though in practice it was interpreted as covering both anyway.)

The urban roads category was previously listed as Bangkok, Pattaya, and municipal areas. The new law changed that to Bangkok, Pattaya, city and town municipalities, and community areas (เขตชุมชน khet chumchon). These “community areas” are supposed to be declared by the local traffic authorities, but it’s still unclear how this will be done in practice. Note that it’s the same word as in the commonly found warning sign that says “เขตชุมชน ลดคาวมเร็ว City limit, reduce speed”, but they’re not technically supposed to refer to the same thing. Subdistrict municipalities (เทศบาลตำบล thesaban tambon) now fall within the non-urban category.

The most significant change here is probably the raising of the speed limit for dual carriageways (those with physical barriers) in non-urban areas. These are default limits, though, and they’re overridden by local traffic ordinances and posted signs.

I understand that current tagging has been somewhat haphazard, with some contributors only tagging posted speed limits and others also tagging based on the national defaults. The latter group will need to be updated to reflect the new regulations, but it’s not really possible to identify the sourcing for all the currently tagged speed limits. Some systematic re-evaluation of current tags will be needed to ensure the correctness of the information, if the community is serious about the update.

In this context, I would like to point out to the table of default speed limits:

tagging maxspeed on every road would now be a problem.
So tagging maxspeed=* is the way to go if there is a physical signs giving a specific limit.
Other roads can fall back to defaults.