C13: Contributing Circumstances, Environment
Apparent environmental conditions which may have contributed to the crash.
This element is divided into Subfield 1, Subfield 2, and Subfield 3. Each have the same attributes for recording up to 3 applicable environment contributing circumstances.
Important to determine existence of unusual conditions that could be useful in determining the need for additional traffic control devices or geometric improvements. (Pedestrians and pedalcyclists are covered in traffic units.)