On Mon, Mar 24, 2008 at 1:01 PM, Ben Laenen <[EMAIL PROTECTED]> wrote: > On Monday 24 March 2008, Andy Allan wrote: > > I think a lot of the physical cycleway tagging is ambiguous at the > > moment, especially with the cycleway= tag. I think cycleway=track was > > intended only for adding to highway=* (not highway=cycleway), but I > > would advise that all off-road cycle paths, including those on > > sidewalks, are drawn as a separate way with highway=cycleway instead. > > I beg to differ here. When you have to tag cycleways belonging to a road > not as "highway=whatever, cycleway=track" but as > separate "highway=cycleway" they just become an editing mess, > especially at intersections. Especially when adding route relations to > them. Just imagine two dual carriage ways with on either side a > cycleway crossing: you then need 24 different ways to just represent > that one intersection, like this: > > |||| > --++++-- cycleway > --++++-- road > --++++-- road > --++++-- cycleway > ||||
I count 8 ways? Unless you are splitting all the ways at absolutely every intersection which is probably a little excessive. Obviously creating a way for every single cycle lane is going to just cause a mess, so where they do just follow the road, on the road, it's probably best to keep them as just a simple tag. However, where they are clearly separate, it's probably best to tag them as you would a dual-carriageway, and for the same reasons. With a separate cycleway you generally can't just hop-on/hop-off without being a menace to other traffic and there's sometimes even a physical barrier; the way can also diverge from the main road way, taking short-cuts round roundabouts or similar. > > But there are more reasons why I don't like these as separate highways: > > * We're also not tagging sidewalks as separate "highway=footway" right > (well, I guess there is not tag for sidewalks yet but it'll come -- but > I can't imagine someone tagging them all like separate ways anyway, > just think about the intersection mentioned above and add > four "highway=footway"s to them). Cycleways are usually between the > sidewalk and the road, so it becomes quite odd that a sidewalk is just > a tag, but a cycleway is its own highway. That's just an argument for modeling the pavement properly. Most pavements are just tacked onto the road as an extra "lane", but with a kerb (to discourage the cars from using it :-) ), so I wouldn't usually bother adding these as separate ways, but where the pavement diverges or is clearly separate, it should probably be modelled as such. > [snip] > > * It's just a lot harder to make them their own highways. it's much > easier to make mistakes. It's possible to argue that one both ways: it's easier to see what's going on and where cycle tracks start and stop, and where exactly they are. > > * Rendering engines could handle it much easier if it were just a > cycleway=* tag added to the road. >From practical experience I disagree. > > * You can usually arbitrarily go from the cycleway to the main road (to > cross it for example). Routing applications could make use of that, if > it's just a cycleway=* tag. Maybe you have to watch out for parked cars > for example, but I've seen cycle lanes where there are parked cars > between you and the road as well, yet the cycle lane is a lane and not > a track. (and before someone mentiones it: yes, relations like the > dual_carriage relation could solve that, but let us first get relation > support in editors a bit better before trying to put more and more into > relations) Potlatch is getting relation support sometime soon.... just awaiting deployment :-) Dave _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
