Figure 2-3. Collision Diagram.
After preparing your diagram, make a search for points of similarity. These may be--
All accident vehicles coming from the same direction.
Colliding cars coming from the same direction such as north.
Accident of one type, such as cars turning left.
Accidents occurring during one season of the year.
Accidents occurring at a certain time of day or during certain lighting conditions.
Accidents occurring under the same weather conditions.
(2) Another useful accident analysis tool is the conditions diagram. See Figure 2-4.