Ben Johnson <[email protected]> wrote: > On the subject of tagging "site unseen"... you brought up a perfectly > legit point about routers and efforts made in the past to assist routing > engines. I'm just trying to get a sense where our community stands in > relation to maxspeed tagging "site unseen", for residential streets, and > how we identify such tagging.
Just to be clear, I'm totally against speed limit guessing based on highway=* type. (site unseen maxspeed tagging). I understand the motivations: that you don't have to change the router, that it encourages corrections and more maxspeed info to be added. It is just that adding potentially millions of default maxspeed tags to residential streets, rather than adding one line of code to a router or exporter seems totally skewed to me, especially when in most case the routing applications will work just fine on residential streets (mostly non-through ways, after all) without this information. Most routers aren't (and shouldn't be) directing people to use residential streets as through routes. Routers presuming a too low speed for residentials (the speed in AU is relatively high) usually yields a satisfactory outcome even when the residential roads don't have a tagged maxspeed. Well intentioned default speed tagging may in fact have the opposite effect, for example in the OSRM default configuration it will cause routing to use residential roads tagged with maxspeed=50, rather than taking a tertiary road with a lower default maxspeed. My only concession to routers, would be that if you maxspeed tag a residential street you should try and also tag the connecting ones if possible, so that routing anomalies don't happen due to speed presumptions. Ian. _______________________________________________ Talk-au mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-au
