Systemic Safety Project Selection Tool

EXAMPLE 3. New York State Department of Transportation Crash Tree Diagram to Select Focus Facility – Long Description

After selecting lane departure as their focus crash type based on an analysis of crash data for the years 2007 through 2011, NYSDOT created a crash tree diagram for the state roadway system to identify the focus facility type for their systemic planning effort. The first level separates the severe roadway departure crashes into rural, urban, and New York City areas. Separating the data into three more levels (divided versus undivided, number of lanes, and speed limit) identifies the appropriate focus facility as those that are rural, undivided, and two lanes with a posted speed limit of 55 miles per hour. The total number of crashes is 6,030 statewide, of which 2,512 are in Rural areas, 1,900 are in Urban areas, and 1,618 are in the New York City area. In Rural and Urban areas, Undivided roads, 2 Lanes, and 55+ mph are the major contributing factors from each level. In the New York City area, Divided and 2 Lane roads with 30-50 mph speed limits are the major contributing factors from each level.