Hi Rob, Am Dienstag, 16. Oktober 2012, 21:42:56 schrieb Rob Nickerson: > 1. Although it is difficult to calculate how many turn restrictions have > some form of "condition", the numbers can't be that many in comparison to > normal restrictions that apply at all times. Adding the condition data to > the "restriction=*" tag therefore will not break the majority of > restrictions (they stay unchanged). Similarly adding the information in a > new tag will not break the majority of restrictions.
Agreed. > 2. For those restrictions that do have conditional details, if: > a) you add the details in "restriction = " you break the current tagging > and routing software will not know how to interpret it. The routing then > does not include the turn restriction (i.e. no restriction when you want > one), or if > b) you add the condition to a new tag then the routing software does not > see it (i.e. you have a restriction when you don't want one). > Both cases need the routing software to be updated... There is one difference for routers which do not know about conditions: (a) lets them calculate illegal routes, while (b) lets them calculate non-optimal routes. Since there are a lot of routers which still fail at certain restrictions, I guess we have to take those routers into account. I therefore definitely prefer (b). > As you see all proposed ideas will need the end users to change something. > And, in fact, as we currently don't have a way of including conditions, we > may already have incorrect turn restriction in OSM. We definitely have them. Here are some from a quick search: http://www.openstreetmap.org/browse/relation/338059 http://www.openstreetmap.org/browse/relation/1735851 (for more, just search through note/fixme tags) > _Conclusion_: Whatever we do should keep the tagging as simple and easy to > understand as possible. As we already have some "applies" type information > in "restriction:hgv = no-u_turn", my gut instinct is to include all the > "applies" type info in this tag. Hence the example "*restriction:hgv = > no_u_turn @ (length > 6)*". This would be (a) from above. Eckhart _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
