OpenStreetMap

Does China really have 4,696,300 km of roads?

Posted by ff5722 on 11 June 2017 in English (English)

It's not exactly a secret that the official Chinese government statistics are often made up or obfuscated. The official stats for road network length say 4,696,300 km of roads. According to the CIA world factbook, China has 4,046,300 km of paved roads. In 2016, on OSM 1,635,931 km of roads was mapped in China. Update: in June 2017 we're already at 2,022,047 km!

Now compare the OSM data of a typical countryside area to the satellite imagery.

Pretty much all unclassified roads are still missing from OSM, and this is the case for most of rural China. Even for cities, there are only a handful of cities that have their residential roads mapped well. So it leaves me wondering, is the 4 million km of roads in total a realistic statistic?

Looking at the satellite imagery again, there are (minor) roads in a grid of about 300 meters distance. The densely populated North China Plain alone has an area of 409,500 kmĀ². Assuming every squared km of this area is covered by 6 km of roads, then there is a total of almost 2,500,000 km of roads in the Northeast China Plain alone. Within villages, the road grid is much more dense. And of course there are plenty of other densely populated areas in China, such as the Sichuan Basin, the Loess Plateau, the Northeast China Plain, the Pearl River Delta etc. etc.

Doing some very rough calculations (area of above regions times 2 km of road per square km):

Is it doubtful that the rest of the country has only 1.3 million km of roads? And this is with a conservative estimate of 2 km of roads per square km (although the Loess Plateau is not that densely populated).

There is also the number of road length per capita. It seems Germany has a comparable population density to China (the population of Western China is neglible). Using the number from Germany (2.81) times the population of China gives around 4,000,000 km of roads. Comparable to the official stats.

The only way to get the answer is by waiting some years for the OSM data to grow further. It's actually likely that even the Chinese government doesn't know the real number, as maps used in China (Baidu, Tencent) lack most of the minor roads. It could be that they censor it, but the purpose seems unclear in that case.

Comment from Mikelatham on 12 June 2017 at 03:14

We should help to better map out China. Even though I'm sure this site is blocked in China.

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Comment from SimonPoole on 12 June 2017 at 09:04

Just a note on the side: the DigitalGlobe Premium imagery looks really good in the area ff5722 referenced, so no reason not to simply trace the roads there. Best by the local community, but that is a bit difficult in the case of China, I suspect if everybody chips in we could have far better coverage in a reasonably short time.

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Comment from ff5722 on 12 June 2017 at 09:44

@Mikelatham No it's not blocked, in fact there are several dozens of active contributors based in China. Just don't go out photographing stuff with a map or GPS tracker in the hand and police won't care (as long as you don't stray near military objects).

@SimonPoole It's easy to trace due to the straight roads, but also kind of a boring task. And not helped by the fact that the chance of anyone travelling these roads guided by OSM data will be extremely slim for many years to come. I did some countryside detailing on a few other places in China, for example here and here. The result is quite satisfying, but with entire suburbs being built in a few years span and 10,000 km of motorway being newly built each year, most of us don't prioritize mapping these minor roads. Of course, everyone is free to do what they want, and it's unique to OSM that there are villages in the middle of Africa with all their buildings mapped, and villages in Germany without any.

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