Review speed limit cases in Thailand that have “mph”


After an analysis of the speed limit values in OSM, we found several regions in Thailand where the value is added using mph, e.g., maxspeed=6 mph, maxspeed=5 mph (miles per hour). According to the legislation of each country, speed is measured in km/h (kilometer per hour): Thailand (Thailand Speed Formats).
The objective is to correct/remove speed limit values that have “mph”, and ensure the value is in the default unit. We found 21 ways with the speed limit in “mph” in Thailand.

Regions we are reviewing:
Thailand: Kathu, Muang Chiang Mai, Thanyaburi, Wihan Daeng.

We will extract all the way ids from these regions and we will correct/remove wrong speed limit values that have “mph”.

For more details, here is the GitHub Ticket.


Great initiative.

When considering the maxspeed tag, it’s important to keep in mind that it should reflect the actual legal speed limit or signage, rather than just a suggestion or physical limit.

I have noticed that some users in Chiang Mai use maxspeed on unsigned narrow or unpaved roads as a recommendation. If you happen to come across such instances, it would be best to also remove them.

Zeichen 274-60 - Zulässige Höchstgeschwindigkeit, StVO 2017.svg200x200

I found also some funny misinterpretations of weight-limits (21t), which I have now fixed. Luckily the initial editor supplied mapillary links for the source.

Seems to be a common mistake. Either bad auto-complete of the tag by editor, or mapper misinterpreting the sign. I fixed 21t and 12t. I have not searched for other typical weight limits.

I’m curious about the typical signed maxweight and maxspeed values that are legally used in Thailand. Does anyone have this information?

Here are some examples. I guess they are in use:

For weight limit I certainly saw the 21t signs. I did a quick search, which also comes up with 20t, 12t, 10t and 5t. This all sounds reasonable. My impression is that the 21t and 12t are quite common. lower limits might be if the building/road in question is weaker.

I guess the situation in Thailand is similar to other countries in which the weight limit is adjusted according to the physical properties. Like a bridge, which can’t handle more weight.

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