Interstate segments have unique characteristics as compared to the non-interstate roadway segments. Without the presence of at-grade intersections and driveways, there are very few conflict points present along interstate segments. Therefore, they were analyzed as part of a separate analysis. Similarly, the segments in between the interchanges along the interstates differ tremendously from the areas near interchanges, so the interstate segments were analyzed separately from the interchanges.
High crash interstate segments were ranked based on three factors:· Crashes Per Mile: the number of crashes that occurred within 150 feet of the centerline of an interstate segment per mile of length
· Crash Rate: the number of crashes within 150 feet of the centerline of an interstate segment per million vehicle miles traveled (VMT) on that segment
· Crash Severity Index: An index that assigns higher weights to crashes that result in injuries and fatalities than to crashes that result in property damage only
The cumulative rank of these three factors became the interstate segment’s score. A segment with a lower cumulative score was ranked higher on the list.
There were high crash interstate segment lists developed for each state. Due to differences in the state crash databases, the Kentucky analysis analyzed each segment in each direction, while the Indiana analysis combined both directions of travel along a given segment.