Service drive requirements

[ccloud20]

In the NCARB site design practice vignette, a "turnaround or drive through circulation is not required for the service drive".

I took this exam a couple of years ago but failed the vignette portion. In my exam, A TURNAROUND OR DRIVE THROUGH CIRCULATION WAS REQUIRED.
I did not have enough room for a drive through so I provided for a turnaround solution but i don't think that what i provided met the minimum requirement of a turnaround.

Could somebody give me some info on the minimum requirements of a turnaround for a service access please?