The jackknife accident is governed by the laws of physics. A fully loaded trailer carrying tens of thousands of pounds of cargo far outweighs its tractor. If its tires lose their adhesion because of sudden braking at highway speed the trailer continues its forward movement even though the cab is slowing down. The energy of the trailer’s forward motion is then transferred laterally, causing the trailer to slide out back-end first, to the right or left. The energy of a fully loaded trailer sliding into oncoming traffic is like a giant hammer delivering hundreds of thousands of foot pounds of energy to anything it strikes. The shifting balance may also cause both the tractor and trailer to spin and lose their cargo, or trigger a deadly underride collision...more