MAINTAIN A SAFE DISTANCE
Maintaining a safe distance from the vehicle ahead of you is essential to driving safely. Heavier vehicles and vehicles under load require more distance to stop.
According to guidelines from The Department of Transportation, heavier vehicles should allow themselves four seconds of distance from the vehicle ahead of them while moving at 40 mph to allow ample stopping time. For every additional 10 mph, add an additional second. For an example, see the diagram below.