The hierarchy of controls is the NIOSH and OSHA ranking of hazard controls from most to least effective: elimination, substitution, engineering controls, administrative controls and personal protective equipment.
Applied to forklift and pedestrian risk, elimination means removing the interaction, for example by moving a process so pedestrians never enter a truck aisle. Substitution can mean using a conveyor or a smaller, slower vehicle. Engineering controls include fixed barriers, guarded crossings, interlocked gates and automatic speed reduction on compatible forklifts. Administrative controls include traffic rules, spotters, training and warning signs. PPE such as high-visibility clothing sits at the bottom.
Detection systems do not fit neatly in one tier. A system that only warns depends on a person reacting, so it behaves like an administrative control. A system that slows or stops the truck through its controls acts more like an engineering control. In both cases detection supplements physical separation and good layout; it does not replace them. The OSHA and NIOSH worksheet uses a fork truck and pedestrian example. See the forklift hierarchy of controls guide.