[OSM-talk] Turn restrictions
steve at asklater.com
Wed Aug 15 22:48:53 BST 2007
So I'm on a train otherwise I'd link to Andys wiki page he pointed to
today, but I want to try out a turn restrictions scheme,
Given a road direction, and roads 'Baker Street' and 'Marylebone
Road' you tag the way 'Baker Street' with
If you can't turn right then it's 'no_turn_right'. If you can't turn
at all it's 'no_turn'. And thats it. There are three major problems
First, as far as I know JOSM doesn't let you use keys more than once
but the API does. So you can't have more than one no_turn_left. So
Second, what if it's no turn for car but ok for bikes, or whatever.
Well, then shouldn't we look at triple tags?
car:no_turn_left:Marylebone Road ? That is, keyvals now have third
string along with key and val? We'd add a third keyval property, call
it what you will, and all the current keyvals will have that third
proprty set to 'general'. So general:name:Foo Street and so on. Then,
this third column can be specialised along the lines of Map Features
as the keys and vals are.
Third, what if someone misspells 'Marylebone Road' or the road isn't
joined, or it doesn't exist or something. Well, people will enter bad
data ON PURPOSE and our map data will never be perfect ANYWAY. And,
it's a wiki so you can fix it. And, it's incredibly simple compared
with any competing scheme I've seen. Also, JOSM (or potlatch) can
prompt you and say 'ah-ha Mr. Mapper, that looks wrong!' And you can
read it, but you can't read bigscheme:way:324543525234:no_turn:34523452.
SteveC | steve at asklater.com | http://www.asklater.com/steve/
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