The Highway Safety Information System (HSIS), established in 1987, is a foundational highway research data system. The State of Washington has participated in the HSIS program since 1993, providing quality data to HSIS for use by researchers through a request system. In 2021, HSIS began a modernization effort with the goal of expanding the technological and analytic capabilities of the data system. This modernization provides an increased emphasis on spatial analysis and cloud-based data management.
 

This guidebook is intended to support the use of Washington State HSIS data for the years 2018 and beyond. Data and documentation prior to 2018 (1993-2017) are available upon request to the HSIS Virtual Laboratory. Prior to 2018, the Washington State datasets included variables for the following files:
 

1. Roadway inventory.
2. Horizontal curve inventory.
3. Vertical grade.
4. Intersection inventory (2004-2009).
5. Accident characteristics.
6. Vehicles involved in crashes.
7. Vehicle occupants involved in crashes.

The revised Washington State database incorporated into HSIS contains six different files:
 

1. Roadway inventory (including traffic information).
2. Horizontal curve inventory.
3. Vertical grade.
4. Crash characteristics.
5. Units involved in crashes.
6. Persons involved in the crash