CONSTRUCTION ACCIDENT - OVERTURN TRACTOR-TRAILER
Review of the Event
A Tractor Trailer Dump Truck overturned to the passenger side while unloading topsoil at a landfill. A portion of the topsoil was stuck in the nose of the trailer. The driver (plaintiff), the raised the trailer, was injured when the overturn occurred. The driver, not wearing his seatbelt, was thrown against the passenger door when the tractor and trailer overturned.
The cause of the over turning of the tractor-trailer was caused by the uneven and uncompacted soil causing the raised trailer to act as an inverted pendulum.
A typical tractor-trailer dump truck dumping a load.
The photograph below shows the tire tracks that the loaded rear tandem trailer wheels make in the uncompacted surface of the landfill.
The photograph below shows a dumped load. Notice the tire track marks in front of the pile of earth. The depth of the tire tracks vary from the right side to the left side. This would cause the extended trailer to oscillate side to side when the load slides out of the rear of the trailer and pushes the trailer forward.
Results of the Calculations
The results of the calculations show that the forward acceleration of the tractor-trailer, in banging the tailgate to the trailer, caused harmonic motion (inverted pendulum effect) of the raised trailer. This inverted pendulum effect exceeded the static overturning torque and resulted in the tractor-trailer overturning.
The case was settled.