Many elements go into ensuring the safety of 

our highways, from program policy decisions 

to roadway and traffic design. To assist safety 

analysts, researchers, and others involved in the 

study of highway safety, the Federal Highway 

Administration (FHWA) operates and maintains 

the Highway Safety Information System (HSIS).

HSIS is a roadway-based system that provides 

quality data on a large number of accident, 

roadway, and traffic variables. It uses data already 

being collected by States for managing the 

highway system and studying highway safety. The 

data are acquired annually from a select group 

of States, processed into a common computer 

format, documented, and prepared for analysis.

HSIS is used in support of the FHWA safety 

research program and provides input for 

program policy decisions. HSIS is also available 

to professionals conducting research under 

the National Cooperative Highway Research 

Program, universities, and others studying 

highway safety.

HSIS

Participating States

In 1987, five States were chosen for HSIS: 

Illinois, Maine, Michigan, Minnesota, and 

Utah. (Michigan’s participation ended in 1997 

and Utah’s in 2000 due to changes in inventory 

data collection.) The primary criteria for State 

selections were the data availability (the range 

of data variables collected), quantity, and quality. 

Safety Data in One Location

HSIS enables users to analyze a large number of 

safety problems. HSIS can help researchers and 

analysts identify problems, examine the size and 

extent of a particular safety problem, and design 

models that help predict future accidents, given 

specific roadway and traffic characteristics. 

In 1995, California, North Carolina, and Washington 

were added to increase the amount of data available and to 

provide better geographic coverage. 

In 2002, Ohio joined HSIS to provide additional 

curvature and grade inventories. Data from the Charlotte, 

NC, urban area were added in early 2011.

This relational database contains basic crash files, roadway 

inventory files, and traffic volume files from these nine 

States. The database also includes information about 

highway intersections, interchanges, and curves/grades 

from some States. Table 1 details the information available 

from each of the currently participating States.

Data Format

All of the data files are stored in the relational database 

formatted files. Data can be extracted in various formats 

such as Microsoft Excel® and Access®, dBase, ASCII, 

etc. or converted to SAS format for analysis. Data can 

be provided via different mediums (CD-ROM, FTP, 

e-mail, etc.). The data can be requested by filling out 

an HSIS data request form online at the HSIS Web site.

Crash files contain basic accident, vehicle, and 

occupant information on a case-by-case basis. 

Typically, this information includes type of accident, 

types of vehicle, sex and age of occupants, fixed object 

struck, accident severity, and weather conditions.

Roadway Inventory files contain information 

about roadway cross sections, types of roadway and 

other roadway characteristics. Data include number 

of lanes, lane and median width, shoulder width 

and type, rural or urban designation, and functional 

classifications.

Traffic Volume files list Annual Average Daily 

Traffic (AADT) data. Additional information on 

hourly volumes and truck traffic percentages is also 

available in selected States and/or locations.

Curve/Grade files contain horizontal curve and 

vertical grade information. Data include degree of 

curve, length of curve, and percent grade.

Intersection files include traffic control type, 

intersection type, signal phasing, and turn lanes 

at highway intersections.

Interchange files include traffic control type, 

intersection type, signal phasing, and turn lanes 

at highway intersections.

All files have been compiled from police-reported 

accident data on State-maintained highways. Table 2 

provides example data characteristics.

Table 1. Data files available in participating States.

CA IL ME MN NC WA OH

Crash       

Roadway       

Traffic 

Volume       

Curve/Grade   

Intersection   

Interchange     
JANUARY 2011

FHWA-HRT-11-031 

HRDS-20/01-11(500)E

Web Site (www.hsisinfo.org)

The HSIS Web site contains links to HSIS 

products such as summary reports, safety analysis 

tools, and various data request tools as described 

below. The Web site can be accessed either from 

http://www.hsisinfo.org/ or by going to 

http://www.f hwa.gov/research and clicking 

on the Highway Safety Information System link.

Guidebooks

Guidebooks are available to help analysts and 

programmers use HSIS. A guidebook for each 

State describes the State’s data system, displays an 

alphabetized listing (by file type) of all available 

variables, defines each category present within 

each variable and presents notes on the quality 

of the variable. The guidebooks are available 

on the HSIS Web site.

Data Element Tables

HSIS also maintains two data element tables 

for all the States. The two tables list each State’s 

crash- and roadway-related variables side by side, 

respectively. These tables enable data requesters 

to compare the availability of variables between 

specific States and are accessible through the 

HSIS Web site.

HSIS Summary Reports

HSIS is used in a wide variety of research efforts. 

Significant results from these efforts are documented 

in HSIS Summary Reports. To obtain copies of these 

reports, visit the HSIS Web site or call the HSIS Report 

Center at (202) 493-3464. 

HSIS Laboratory

The HSIS laboratory at the Turner-Fairbank Highway 

Research Center provides a working environment 

that enables FHWA and on-site project staff to study 

and analyze highway safety issues and to provide 

support for users including the following: 

• Research files and support. Staff works with users 

to define file components and layouts and merges 

data from crash and other files as needed. Staff also 

provides on-going support in data interpretation and 

data merging.

• Fatality Analysis Reporting System (FARS) and 

National Automotive Sampling System General 

Estimates System (NASS GES) files and output. 

In addition to HSIS State data, staff can provide 

support to users wishing to analyze FARS data and 

data from NASS GES. 

• Support for geographic information system (GIS) 

tools. Staff provides support for GIS-based safety 

analysis tools described on the HSIS Web page 

(e.g., spot intersection analysis, safe routes for 

walking to school).

For more information about HSIS, 

contact:

Carol H. Tan, Ph.D. 

Federal Highway Administration 

Office of Safety R&D 

6300 Georgetown Pike, Room T-210 

McLean, VA 22101 

Phone: (202) 493-3315 

Fax: (202) 493-3374 

E-mail: Carol.Tan@dot.gov

The Essential Information 

System for Making Informed 

Decisions About Highway Safety www.hsisinfo.org

Table 2. Data characteristics for participating States.

First Year 

Available

Average 

Crashes 

per 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