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Steven M. Schorr, PE ::::

Case Synopsis: Southbound (SB) tractor-trailer operator is executing a left turn across the northbound (NB) lanes in an attempt to head eastbound (EB) at an intersection. The tractor-trailer is turning from an exclusive left-turn lane, across the path of the opposite left-turn lane, and across two NB lanes. As the truck is turning, a NB vehicle strikes the passenger side front of the tractor. The tractor-trailer operator testified that he looked for approaching NB traffic prior to turning, but saw only a small truck moving into the opposite left-turn lane. He claims that the small truck must have obscured his view of the vehicle that struck him.

Expert Analysis: A three-dimensional (3D) environment was created in the computer to accurately represent, to-scale, the intersection, the approaching roadway, and the involved vehicles. The relative speeds and resulting positions of the vehicles were evaluated within the 3D environment. Cameras [to represent the eyes of the tractor-trailer operator] were placed within the 3D environment. The computer-aided, 3D analysis determined that no matter where the small truck was located approaching, and moving into the left-turn lane, the operator of the tractor-trailer, especially from his elevated position, should have seen the vehicle that ultimately struck him. The 3D environment was also used to evaluate the length of time that the left-turning tractor-trailer was visible to the NB vehicle operator and whether, despite the actions of the tractor-trailer, the northbound vehicle operator had an opportunity to avoid the collision.

Result: The engineering analysis, including the 3D environment, established that the left-turning tractor-trailer operator should have seen the approaching NB vehicle prior to and as the truck was executing the left turn. Further, once the tractor-trailer started the turn, the approaching vehicle operator did not have sufficient times or distance to avoid the collision.

, with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.