Re: [Talk-us] Does only_straight_on imply no_u_turn?
Randy wrote: > I would not count on only_straight_on as being interpreted as no_u_turn; > nor would I assume no_left_turn includes no_u_turn as a default. 90% or > more of the time the implication would be there, but there are some cases > where a U-turn may be permitted at a traffic light, against the designated > traffic flow. Much better, and more flexible, to overtly include all > restrictions. In Washington State, one can U-Turn anywhere they can do so without blocking traffic unless specifically restricted by signage or local ordinance. ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Does only_straight_on imply no_u_turn?
On 1/8/10 12:59 PM, Randy wrote: > Alan Mintz wrote: > > >> When tagging a T-shaped intersection like this: >> >> B >> B >> B >> B >> AAA+AAA >> >> if you tag a no_left_turn restriction from A into B, it renders (in JOSM >> anyway) as an arrow going straight and right. This doesn't make sense in >> these T-intersection cases because there is no road continuing right from >> the intersection. So, I've been tagging these as only_straight_on instead, >> which effectively is the same thing, but renders better (though not the >> same as the sign). >> >> However, in tagging a no-left/no-U at such an intersection, I realize that >> "only_straight_on" might also imply no_u_turn, in which case most of my >> previous tagging in the case above is wrong, since most of them were >> no-left-turn signs only (i.e. U-turns are allowed). >> >> Does only_straight_on imply no_u_turn (in addition to meaning no left and >> no right)? If so, does it make more sense to render no_left_turn as a >> left-turning arrow with a line through it, instead of the current >> straight+right arrow? >> > I would say this is a very good example of don't tag for the renderer. actually, i think there is a bit of discussion on rendering on the turn restriction relation page, and i think it is to a degree wrongheaded as it shows equvalencies between the red "can't" and blue "can" signs that aren't correct if there are oneway tags in place. JOSM renders with the blue "can" signs, and ignores any underlying oneway tags on the ways, with the result that we can clearly see the sometimes wrongheaded rendering that the Turn_restriction wiki page calls for. since it's still apparently a proposal, i suggest we should amend the discussion on it and see about getting this fixed. richard ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Does only_straight_on imply no_u_turn?
Alan Mintz wrote: >When tagging a T-shaped intersection like this: > > B > B > B > B >AAA+AAA > >if you tag a no_left_turn restriction from A into B, it renders (in JOSM >anyway) as an arrow going straight and right. This doesn't make sense in >these T-intersection cases because there is no road continuing right from >the intersection. So, I've been tagging these as only_straight_on instead, >which effectively is the same thing, but renders better (though not the >same as the sign). > >However, in tagging a no-left/no-U at such an intersection, I realize that >"only_straight_on" might also imply no_u_turn, in which case most of my >previous tagging in the case above is wrong, since most of them were >no-left-turn signs only (i.e. U-turns are allowed). > >Does only_straight_on imply no_u_turn (in addition to meaning no left and >no right)? If so, does it make more sense to render no_left_turn as a >left-turning arrow with a line through it, instead of the current >straight+right arrow? I would say this is a very good example of don't tag for the renderer. The information you have given is adequate for a renderer to properly label the intersection (no left turn + no highway to the right). A renderer should be able to take this (not so) special case into consideration in labeling the flow directions. While only_straight_on is also valid, since it is the only available option when no left turn is allowed, consider this: If the the N-S highway, in your example, were ever extended, then someone would have to notice the restriction in the relations and change it or right turns wouldn't be routed. Better, in my opinion, to stick with the signage. I would not count on only_straight_on as being interpreted as no_u_turn; nor would I assume no_left_turn includes no_u_turn as a default. 90% or more of the time the implication would be there, but there are some cases where a U-turn may be permitted at a traffic light, against the designated traffic flow. Much better, and more flexible, to overtly include all restrictions. -- Randy ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
[Talk-us] Does only_straight_on imply no_u_turn?
When tagging a T-shaped intersection like this: B B B B AAA+AAA if you tag a no_left_turn restriction from A into B, it renders (in JOSM anyway) as an arrow going straight and right. This doesn't make sense in these T-intersection cases because there is no road continuing right from the intersection. So, I've been tagging these as only_straight_on instead, which effectively is the same thing, but renders better (though not the same as the sign). However, in tagging a no-left/no-U at such an intersection, I realize that "only_straight_on" might also imply no_u_turn, in which case most of my previous tagging in the case above is wrong, since most of them were no-left-turn signs only (i.e. U-turns are allowed). Does only_straight_on imply no_u_turn (in addition to meaning no left and no right)? If so, does it make more sense to render no_left_turn as a left-turning arrow with a line through it, instead of the current straight+right arrow? -- Alan Mintz ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
