All good points Bob.
I'm just thinking that we need to have a default, well defined, path to follow when there is no double yellow line or light pole that makes sense to use. I would propose that your "control points" be the edges of the streets. That is, if the runners are traveling north in the right lane they must stay in the right lane until they are even with the south edge of the cross street. Then they follow a straight line to the point on the south edge of the right lane of the cross street that is even with the west edge of the north-south street. Not sure if that's clear. Maybe a picture is needed.
A description of a standard way of doing this would be good because I see a lot of maps that don't have detailed descriptions of how these turns are done.