 Brake lag distance also needs to be taken into account. When operating a vehicle with air brakes, it takes about half a second for the mechanical operation to take place. Finally, braking distance is the distance it takes a vehicle to stop once the brakes are applied. Braking distance is affected by the weight, length, and speed of the vehicle, as well as road condition. This tip was brought to you by JJ Keller and Associates. Visit us at JJKeller.com.