Employers and duty holders must make sure that the working site is suitable for the vehicle to operate safely.
Your risk assessment should include answers to these questions:
If work has to be done above ground level, and permanent, safe access cannot be achieved using platforms, gantries or other site measures, arrange other types of safe access.
Moveable steps (not attached to the vehicle) are safer to climb than vehicle-mounted ladders.
Think about signs showing trip, slip, fall or other general hazards wherever there is a significant risk of an accident. But do not put up so many signs that drivers ignore them as part of the 'background'.