An automatic braking system and method are provided for controlling the automatic operation of a pneumatic (air) brake system installed on commercial highway vehicles and the like, particular heavy trucks and buses. When a possible collision is detected or an object is detected in proximity to at least one side and/or end of the vehicle, the system automatically operates the existing, factory installed air braking system of the vehicle to avoid a collision or mitigate the collision impact by concurrently pressurizing each of the rear and front pneumatic service brakes of the vehicle. Pressing the existing vehicle brake pedal deactivates the automatic braking system, thereby permitting the driver to take over control of braking at any time.