The Traffic Accident Reconstruction Origin -Approach Angles Problem-
This is a two car collision that occurred on a sunny weekday afternoon. Each of the involved cars contained one driver, and no passengers. Both drivers were transported from the scene by ambulance. After receiving treatment at a local emergency room both were released.
This collision occurred at the intersection of Army Rd. and the exit of a shopping center. Army Rd was a six lane divided asphalt road. It was posted with a speed limit of 45 m/h. The shopping center exit was divided and had two lanes entering and two lanes exiting. The intersection was signalized. Traffic turning from Army Rd. into the shopping center faced a five section head that allowed exclusive or permissive left turns.
Mr. Smith was a 40 year old male who was on his way home from work. He was driving his teal 1993 BMW 325i northbound on Army Rd. He needed to stop at the shopping center to run some errands. So, as he approached the intersection of Army Rd and the shopping center entrance, he moved into the left turn lane. He states he was facing a solid green traffic light. He looked north, saw no hazards approaching and began his left turn.
Mr Jones was a 25 year old male who was on his way to work. He worked as a bartender and was admittedly "late for work". He had a suspended drivers license, expired insurance and an expired tag on his brown 1986 Dodge Lancer. He was driving south on Army Rd in the center through lane. He states he was traveling near the speed limit, facing a solid green light, when he saw the teal BMW turn into his path. He braked dramatically and swerved but was unable to avoid the BMW. The cars collided. He states just after the collision he attempted to drive his Lancer off the roadway but the car wouldn't move.
Mr. Smith is sure of the following: He looked north before he made his left turn. He saw no approaching vehicle. He is forced to conclude that the Lancer was speeding.
Physical Evidence on the Roadway
There are two prominent slid marks in the center southbound lane of Army Rd. These marks begin north of the stop bar and continue their parallel path into the intersection. Once in the intersection there is an obvious offset in both marks. The marks continue, roughly parallel for a short distance then, the left mark disappears and the right mark changes in appearance. The right mark remains black but there is also a black grainy substance along this last section of the mark. This mark ends under the rest location of the right front tire of the Lancer.
|Diagram of collision scene showing skid marks,
rest positions of vehicles, and intersection layout (10 Kb gif)
|Detail measurements of skidmarks (9 Kb gif)|
|View looking south along the Lancer's approach. Note
Skid marks apparent in the center of the photo. The foreground
of this photo documents the skid mark beginnings (61 Kb gif)
|View looking south at Lancer's rest. The skids are straight
In the photo foreground, then change directions twice prior to
reaching the right front tire. (58 Kb gif)
|View looking south at both vehicles sitting at rest (53 Kb gif)|
|View looking south at the right rear of Lancer at rest (66 Kb gif)|
|View looking east at right front of Lancer at rest (58 Kb gif)|
|Close up of Lancer damage. Note the black
granular substance on the roadway. (77 Kb gif)
|View looking north west at right front of BMW at
rest. Note: the only damage in this photo is to the right
rear quarter. (70 Kb gif)
|View looking north east at right rear of BMW at rest.
Note deformed bumper cover exposing the
Styrofoam underneath. (63 Kb gif)
|View looking west at the BMW. This photo details
the contact damage. (60 Kb gif)
Solution by Brian Mc Henry
Solution by John Bates