10.3.5.1 Historical Crash Analysis Intersection Crash Rate
Intersection crash rate is a diagnostic tool rather than a predictive tool. It is calculated from historical data to determine the safety level at an existing intersection. Crash rates calculate the number of crashes for a given period and location over a measure of exposure in terms of traffic volume. They help account for low volume intersections with a seemingly low number of crashes that are experiencing a high crash exposure. Crash rates are used to prioritize intersection improvement projects identified through network screening, when resources and funds are limited. The intersection crash rate equation is:

Where:
R = Crash rate for the intersection expressed as crashed per 1 MEV
C = Total number of intersection crashes in the study period (typically three to five years of data)
V = Traffic volume entering the intersection daily (obtained from traffic management center data or AADTs) per approach
N = Number of years in the study period