Hi Laurent, thanks for your analysis, very appreciated! Also the knowledge in different countries is nice to have :)
I can remember we excluded those tracks as it was very unusual in most countries with grade > 1. So yes, if this is required then it is very important to include grade2 and even 3 (I'm not sure if higher), maybe we make this configurable in the CarFlagEncoder and per default it is 2? Later we make this country-specific (#175) (BTW: The only downside will be that more streets are added to the network and algorithms without CH will be slightly slower for long routes) Also I found this related issue (not yet looked again into it :)): https://github.com/graphhopper/graphhopper/issues/253 Regards, Peter On 06.01.2015 12:40, Laurent Bendel wrote: > OK, the code is actually pretty readable, I did my homework. It turns out the > algorithm turns down tracks with tracktype=grade > 1. From > CarFlagEncoder.acceptWay: > > if (tt != null && !tt.equals("grade1")) > return 0; > > by changing this to > > if (tt != null && !tt.equals("grade1") && !tt.equals("grade2")) > return 0; > > I get correct results, and given the very low weight given to such tracks, it > shouldn’t impact much other routings. Or would it ? > > According to http://wiki.openstreetmap.org/wiki/Key:tracktype, grade2 should > definitely be acceptable for a general purpose vehicle, grade3 probably too. > As for the example outlined below (no man’s land between Mauritania and > Morocco), it’s actually more like a grade4, mostly compacted sand, some soft > sand. Still crossed by all kind of small cars every day. So if somebody > corrects OSM with the more correct grade type, the routing will again fail. > But this is unavoidable in the grand scheme of things. > > Any thought ? submit a patch ? > > Laurent > > PS: note that in Australia, some tracks are labeled highway=secondary or even > highway=primary, so the problem doesn’t exist. > > On 5 janv. 2015, at 19:34, Laurent Bendel <[email protected]> wrote: > >> Hi there, >> I’m new to graph hopper, but I’ve already spotted a problem: it seems the >> algorithm decides that tracks (highway=track) are impassable by cars, but OK >> for bikes. E.g.: >> >> https://graphhopper.com/maps/?point=Dakhla%20الداخلة%2C%20Morocco&point=Nouadhibou%2C%20Mauritania&layer=MapQuest >> >> The problem is, in quite a few countries outside of Europe, main roads can >> be so bad that they are classified as tracks, but still used by thousands of >> normal cars, buses and lorries. The border between Mauritania and Morocco is >> a typical example, it is actually the only link between North and West >> Africa..! Maybe they should be weighted « less » than highway=unclassified, >> but still taken in account. Any reason it is implemented this way ? >> >> I’m using the graphhopper.com service, not my own server. >> >> Thanks, >> Laurent >> >> > > _______________________________________________ > GraphHopper mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/graphhopper _______________________________________________ GraphHopper mailing list [email protected] https://lists.openstreetmap.org/listinfo/graphhopper
