Turner-Fairbank Highway Research Center

 
 
 
 

State Statistics

File Types

All of the selected States maintain basic crash files, roadway inventory files, and traffic files. In addition, individual States also collect other types of data. Depending on the particular problem being studied, files from one or more States may be used by the analyst. The following table indicates the files that are available.


CA IL ME MI MN NC OH UT WA
Crash X X X X X X X X X
Roadway X X X X X X X X X
Traffic Volume X X X X X X X X X
Curve/Grade
X



X X X
Intersection X
X
X



Interchange X X X X X


X

Crash — Contains basic accident, vehicle, and occupant information on a case-by-case basis. Typical data include type of accident, type of vehicle, sex and age of occupants, fixed-object struck, accident severity, and weather conditions.

Roadway — Contains information on roadway cross-section and the type of roadway. Data include the number of lanes, lane width, shoulder width and type, median width, rural/urban designation, and functional classification.

Traffic Volume — Contains annual average daily traffic (AADT) data. Additional data on hourly volumes and percentage of trucks is also available in selected States and/or locations.

Curve/Grade — Contains horizontal curve and vertical grade information. Data include degree of curve, length of curve, percent grade.

Intersection — Contains information on highway intersections. Data include traffic control type, intersection type, signal phasing, and turn lanes.

Interchange — Contains information on highway interchanges. Data include interchange type and ramp characteristics.

Data Quantity

HSIS contains only police-reported accident data on the State-maintained highway system. The size of the State-maintained system depends on the policies of the State and is not necessarily proportional to the size of the State. Data for the original five HSIS States are available from 1985, while data for the three new HSIS States are available from 1991, and data for Ohio is available from 1997. The following table provides an indication of the quantity of data available.


First Available Year Average
Crashes/Year
Roadway
Mileage
California 1991 171,000 15,400
Illinois 1985 144,000 17,300
Maine 1985 37,000 23,300
Minnesota 1985 77,000 57,300
North Carolina 1991 112,000 64,400
Washington 1993 43,000 7,200
Ohio 1997 132,000 18,300