A tractor trailer was traveling through a construction zone when it hit a very large, 12 inches wide by 14 feet long, pothole in a temporary asphalt patch in a roadway diversion within the construction zone. The right front steering axle wheel hit the construction zone pothole. The driver claimed he lost control of the steering and ended up trapped when the tractor flipped onto its side and crushed the driver compartment. The right side of the tractor and steering axle which struck the pothole is shown in Photograph A.
Photograph A View of right (passenger) side of subject accident tractor.
The left, or driver side, of the tractor trailer after the accident is shown in Photograph B.
Photograph B View of driver's side of subject tractor accident.
The allegation was that lack of or improper maintenance of the vehicle steering and spring system resulted in a loose connection in the right front leaf spring assembly. Upon impact with the pothole, the right front wheel and steering axle moved rearward, causing a loss of steering control resulting in loss of vehicle control and flipping of the tractor and trailer onto its side. A view of the end of the right side fuel tank confirmed that the right front steering axle tire had moved rearward and had carried and trapped the mud flap into the front of the fuel tank. Photograph C shows the tire tread witness mark or contact evidence finger print to that event.
Photograph C View of mud flap imprint on front of fuel tank.
Examination of the right front leaf spring assembly confirmed that the U bolts were deformed and that the leaf spring assembly had moved rearward and displayed some rearward displacement post-accident. The bent U bolt and rearward displaced leaf spring assembly are shown in Photograph D.
Photograph D Bent front spring U-bolt on right side of subject tractor.
A view looking up at the displaced right leaf spring assembly is shown in Photograph E.
Photograph E Rearward movement of right front tractor leaf spring.
An arrow marks the sheared leaf spring to pillow block keeper pin. The sheared keeper pin is displaced about 3 1/2 inches rearward, post-accident.
A close-up view of the sheared keeper pin is shown in Photograph F. A white arrow denotes the sheared keeper pin.
Photograph F View of sheared right front spring keeper pin.
One or more attending experts wanted to measure the nut breakaway torque. As can be seen, the rear U bolt is highly deformed (see arrow) as shown in Photograph G.
Photograph G Close-up view of left front spring U-bolt.
A close-up view of the nut and threaded end connection of the deformed U bolt shown in Photograph G is shown in Photograph H.
Photograph H View showing deformation of U-bolt.
An uneven gap between the U bolt nut and washer, resulting from the deformation of the U bolt, is easily discernable. The gap between the nut and the washer is denoted with a white arrow. Such a gap would make breakaway torque measurements meaningless.
Following review of the evidence, the plaintiff changed direction in the litigation and this investigation was terminated.