A helpful question to ask is: what is the intended purpose of the hi-vis vest?
The answer is likely to be: to increase the visibility of the worker to protect against being run in to.
Then consider the circumstances in which the forklift is operating:
- If the worker is operating the forklift without any other vehicles in the vicinity, (e.g. a single forklift in a warehouse) the hi-vis vest does not provide any protection, so (unless the area is zoned a compulsory hi-vis area for other reasons by the PCBU), there is no legislated requirement to wear the vest while driving the forklift.
- If a worker is entering an area where other vehicles are operating in order to drive the forklift, then that would be a very good reason to wear the hi-vis vest, to increase the visibility of the worker for other drivers.
- Some workplaces expect all workers to wear hi-vis vests to distinguish them from others in the vicinity, which may also have a range of safety implications.