On a test track in the new Volvo FH, together with test drivers you get to experience how the Collision Warning with Emergency Brake system can avoid a rear end collision, even if its tight! The tractor trailer is fully loaded to 40 tons GCW.

Now load it up with full cargo and see how well it does. The reason trucks and other heavy vehicles have a long breaking path is because of inertia from it's own weight.

A truck cabin with an empty trailer can stop pretty fast, but load up the trailer and then try this, the inertia of the trailer will push the truck.