OpenStreetMap
[Ed note: this is a ‘preprint’ because my usual blog has technical problems]
A few days back I read this article about the longest straight lines on land and sea and I wondered how routers would handle the load, at least for the land one.
So I set up a route between Rua da Fortaleza, Sagres, Portugal, and what looks like the main square in Quanzhou, China. SRTM and GraphHopper handled the request just fine, while for some reason valhalla didn’t. Then I upped the stakes, by requesting foot routes. Foot routes are harder because the foot network is way bigger than the road network. SRTM and GH succeeded, but not without some effort. I tried to benchmark it, but it seem at least OSRM seems to cache the results, which makes sense. Interestingly, the route more or less follows the great circle all the way down to around Tyumen, Russia, where it starts to deviate more and more as the roads become less and less frequent. Also, OSRM proposes a land only route, while GH also includes ferries, but that depends on how OSM uses GH and how GH (and probably OSRM too) are configured.
I also read the foot notes on that article[1]. It mentions that Sagres is also the end of the longest land route, period; the other end is in Russia. First thing to note is that is says that the end is close to the North Korea border, “the eastern terminus of that country’s road network”. I wonder where he got that nibble, because I found there are connected roads almost all the way to the Chukchi Peninsula, crossing the antemeridian. I found that all routers choke there. So the calculation for the longest foot route will have to wait until this is fixed; I’m not going to settle for partial results :)
Lastly, That Other Map does not even has those routes, so technically they don’t have that problem :)
[1] you do that, right? :)
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