OpenStreetMap

Calculating the mapped road coverage in your region

Posted by PlaneMad on 18 January 2016 in English (English)

A few months back in the OSM India community, we were curious to know how much of the trunk network of National Highways has been mapped compared to the official statistics released by the government.

We started off by aggregating all the statistics we could find from various official sources on the road lengths for different types of roads into a common spreadsheet.

Next was to calculate the corresponding length of roads in each state mapped on OSM. To do this, I used the osm-coverage tile reduce processor with added support for Admin-1 regions from natural earth vectors.

All it takes to run this for the Indian subcontinent is:

npm install

node download.js --all

node index.js --area=[56,-12,116,42] > output.json

To generate per highway tag road length in kms for each state in the bbox. The processing should not take more than 5 minutes.

These numbers were used to compare with the official figures and generate a list of states where the national highway coverage needs to be improved.

Try it out for your area and see if it helps detect missing highway networks. The code is in the regions branch of the processor: https://github.com/mapbox/osm-coverage/tree/regions

Happy to hear feedback on how it worked and how the processor can be improved.

Comment from bojan12 on 18 January 2016 at 13:31

looks interesting

Comment from Heinz_V on 18 January 2016 at 19:59

Your statewise length of the NHs is completely out of date or full of errors. See the wiki-page for exact values. http://wiki.openstreetmap.org/wiki/National_Highways_%28statewise%29

Comment from PlaneMad on 19 January 2016 at 02:28

Heinz, the calculations were done a few weeks ago, but its still interesting to note the differences in length. If you can share the process you followed to do this it will help find the cause of the variation.

Comment from yogi_ks on 19 January 2016 at 12:38

It will be nice to know the process followed by Heinz to get the highways length mentioned on the wiki page. I used the old osm-length-2.pl perl script for Karnataka region from latest OSM extract to get highways length and got approximately similar length(~7789km) as in this common spreadsheet.

Kar

Comment from PlaneMad on 19 January 2016 at 16:11

Thanks Yogi, this is useful. Atleast we now know the numbers are not completely off. One thing to note is that both the pl and the osm-coverage script will be giving slightly higher counts due to dual carriageways. Still uncertain how badly this affects the final value.

Comment from Heinz_V on 23 January 2016 at 01:35

The NH-length in Karnataka is 6434km(OSM) and 6502km (MORTH. My calculatons take care of dual-carriage parts and road parts that are shared by two NHs (no double counting). I created for each NH-road seperate relations and calculate the length with the relation analyser. If the mapping is precise, than my calculations are also precise. A little problem is that the state boundaries are not mapped excatly. And it’s not clear what to do with NHs in big cities without a ref-tag. Does Morth count these roads??

Login to leave a comment