It’s unfortunately common to begin a ramp or slip lane at the beginning of the lane change restriction. However, a more accurate modeling would be turn:lanes=* plus change:lanes=*. This is especially helpful in regions where a solid white line technically only discourages changing lanes and it’s legal to cross the line, for example when pulling out of an adjacent driveway.
Some of the most prolific corporate mapping teams didn’t get the memo, so when we go back and add lane-level detail, we often have to move the start of the slip lane back by some distance.
The blue line represents the “Kreuz Köln-Sud solution”, which hasn’t nearly achieved 99% adoption, though it is the most talked about.