Add an obstruction to one side only
The next part of this lesson requires a pallet standing on it's edge or other similar obstruction. This is placed at a distance away from the drum or cone so that when the truck is driven around the drum, staying close to it, the rear of the truck only clears the pallet by around 50 to 75 mm.
Again starting on the easy side, typically the left, the trainees are instructed to drive towards the cone, make a turn around it but at the same time ensuring that the rear end of the truck misses the obstruction.
They should then go back to the starting point and make a second attempt. This should be repeated as many times as the trainee needs but the idea is for the instructor to make sure the trainee can get around the drum without hitting anything and at the same time whilst checking all-round from obstructions.
I always found that a piece of French chalk was a most useful addition to the instructor's "toolkit" because as these exercises progress, things usually get moved or knocked over.