The Traffic Accident Reconstruction Origin -Approach Angles Solution-

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### A Solution by Charles Veppert

Old proverbs notwithstanding, some pictures speak a thousand questions. This photograph offers allot of information but also begs for more.

The tire marks, which enter the bottom of the photograph, appear to be from a dual wheel pickup or small straight truck. They are full braking skid marks made in a panic brake situation. The longest skid marks are from the front wheels, identified by the overdeflection of the front tires due to weight shift. It is particularly noted in the left front skid mark, which displays the classic dark outer edges. The outer skid marks were left by the rear dual tires, which were unloaded by the same weight shift and show the tread pattern of the tires. The sudden deviation in direction undoubtedly comes from a near 90 degree impact from the right, which caused the truck to move left and rotate slightly counter-clockwise though still retaining most of its forward momentum. The impact was likely just ahead of the center of mass of the truck.

Given the length of the visible portion of the skid marks it would appear that it traveled at least 3 wheel base lengths to impact and nearly another length post-impact. Using a wheelbase of 14 feet it slid about 42 feet pre-impact and about 56 feet to rest. Using an average value of f = .70 for asphalt this gives a pre-impact speed loss of 30.7mph and a total loss of 35.4mph. This of course assumes that grade is not a factor. Post impact travel does not seem to be a function of impact but from the trucks own momentum.

The tire marks curving in from the right appear to be from vehicle #2 as they correspond to the direction of the impulse. Any conclusions about #2 are dependent upon vehicle mass. In order to redirect the truck as it did, it may have been a small car at a slow speed or a motorcycle at high speed. At any rate, it does not appear that it was panic braking as the truck was, but rather leaving a scuffmark prior to impact. It is also possible that this mark does not pertain to this crash at all.

The white dashed lines that travel across the photo appear to be lane lines outlining the path for vehicles making a left turn through an intersection. If so, that would mean that there are multiple lanes approaching from the right and the crash occurred in the middle of a large intersection.

Of considerable interest are the apparent gouges that cross the truck skid marks post impact. They could be old gouges that were already in the roadway, but could also be post impact and have erased the trucks skid marks as they were gouged out.

Charles Veppert is 40 years old. He, his wife Joyce and their two children, Christopher and Shelby live in Mogadore Oh.

He is a Sergeant with the Ohio State Highway Patrol assigned to the Ohio Turnpike, one of the safest highways in the nation. For the past 11 years he has been a member of the Ohio State Highway Patrol's regional crash reconstruction unit. He holds ACTAR certification #696.

Mr. Veppert can be reached at [email protected]

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