Why is there so much less traffic sign data in Japan?

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Hi,
Can anyone help me explain why I use “traffic_sign=*” to look up Japan traffic signs and get very few results. Is this normal? Is the traffic sign data not entered in Japan, or my query keyword is incorrect (normal in other countries)?

Thanks a lot.

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The amount of OpenStreetMap data varies wildly in different countries depending on number of volunteers and whether there are suitably licensed alternate sources that can be imported.

I think the level of completeness for Japan in general isn’t very good from the few things I’ve looked at previously.

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And traffic sign mapping is really on extreme side of micromapping so coverage anywhere will be really low.

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Open data is quite good in Japan. There’s access to the national government’s map and imagery (although there have been changes in the licence to some before), as well as most if not all local government if asked. There have been many imports, including place= previously, and 3D building= ongoing. It’s basically the limited number of users relative to the country size.

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To explain the problem:

If there is a max_speed=50 value on a road itself, it is quite easy to develop applications for routing etc that use that value. But if you have a separate point next to the road with traffic_sign=max_speed & max_speed=50, it becomes much harder to use it. Like how do you know which road that speed sign applies to? The obvious first pick of anyone would be the closest one but first I can guarantee that there will be significant percentage of cases where that is wrong, and additionally you may not know in which direction of the road it applies to.

In summary, if you want to map traffic rules, apply them to the road, not by mapping the signs themselves.

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