On Thu, 23 Apr 2009 22:19:39 -0700, Paul Johnson <[email protected]> wrote: > In Salem, Oregon, I have encountered a ramp that I can't quite seem to > make a restriction that JOSM thinks is valid, so I'm wondering what the > expected way to handle such a situation is. The area in question is > visible at > http://www.openstreetmap.org/?lat=44.929397&lon=-123.024784&zoom=18&layers=B000FTF > > Coming from the flyover ramp to Mission Street eastbound, as well as > from the Mission Street bike lane ramp where that lane rejoins the road, > drivers and cyclists alike are faced with a No Lane Change line that > prevents a legal movement to the left turn lanes onto 17th Street. > Effectively, this means that you may or may not be able to turn left at > 17th depending on how you entered from the next intersections west. You > can see the pavement markings as they are on the ground at > http://maps.google.com/?ie=UTF8&ll=44.92934,-123.02527&spn=0.000872,0.002414&t=k&z=19 > > For those who aren't familiar with why this is a hard question: > > 1) JOSM doesn't seem to want to have more than one "via" or have a way > as a "via" in a restriction relation; I'm not sure if this is right or > wrong for JOSM to expect. What's the live use on this? > > 2) Solid white lane lines mean you can't change lanes in this area > (exception being bicycles are allowed to enter or leave their restricted > lane over the solid line adjacent to the bicycle restricted lane). > > 3) Only one lane change is allowed per vehicle per 1000 feet. Lane > changes are unrestricted between all lanes for 60 feet between the two > intersections, and traffic moves at expressway speeds (40-50MPH). > > So how does one handle such awkward turn restrictions (other than > slaughtering the civil engineer who came up with such a bogus > interchange to begin with)? This is not a turn restriction, as you are allowed to turn left from the road, but rather a lane change restriction. This must be handled in the map somehow as well, but there is no way to tag it at the moment to my knowledge. I suggest somebody start working on a lane relation, as much information lies in lanes, such as specified lanes for left and right turn, off-ramps, where you can change lane, where you cannot change lane, differented restrictions in different lanes (such as you cannot change between the left-most lanes where an onramp comes on right-hand side of a motorway, restrictions applying only for one movement, not the other (i.e. you can change lane to the left, but not to the right). I am more than willing to help you form such a relation, but doesn't have time to do the work myself. -- Brgds Aun Johnsen via Webmail
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