Not used in autocross? Not on airfield courses (no room), but I've seen 'em on sites with more open pavement. Try this and scale to your liking. You can box the whole 180 if you want -- that also allows you to make it optional direction -- doesn't matter which side of each double cone you enter on, so long as you exit on the other.


[edit] Nuts -- ACSII art didn't work. Basically, the apex cones are a double cone set spaced to define the length of the switchback. Completely or partially box the space around them to define the 180s.