Originally Posted by
KerryIrons
Coincidentally I just saw this discussed on the Association of Pedestrian and Bicycle Professionals list serve. I had forgotten the term but indeed it is a "two stage turn." For those who think this is not to be done, look it up.
As long as there's an understanding a two-stage turn (with or without the marked box and other devices) is different from a "right-U" maneuver (either with or without the subsequent right), then it's all good. Although the right-U achieves the same result as the TSTB, it has different interactions with traffic.
The two-stage turn box markings and signs are covered in Interim Approval IA-20, which can be seen at
https://mutcd.fhwa.dot.gov/res-interim_approvals.htm