What must be done before leaving a parked vehicle?

Setting the parking brake and chocking the wheels is crucial when leaving a parked vehicle, particularly when on an incline or uneven surface. The parking brake helps secure the vehicle in place, preventing it from rolling unexpectedly. Chocking the wheels provides an additional layer of safety by physically blocking the wheels, further reducing the risk of movement.

This combination is especially important in commercial or industrial settings, such as at substations, where heavy vehicles might be parked and could cause significant hazards if they were to move unintentionally. While locking the doors is certainly a good security measure, it does not ensure that the vehicle will remain stationary. Simply turning off the engine or leaving the parking brake off can lead to dangerous situations, especially if the vehicle is parked on a slope. Thus, setting the parking brake and chocking the wheels is the most comprehensive method for ensuring vehicle stability before leaving it unattended.