Highway engineers and administrators are continually faced with decisions concerning the design and operation of the highway system. An important part of the decision-making process is the potential impact on the safety of the highway users. Informed decision making requires an understanding of how safety is affected by the geometric design of the roadway, the selection and placement of roadside hardware, the use of traffic control measures, the size and performance capabilities of the vehicles, and the needs and abilities of the users. 

The Federal Highway Administration (FHWA) developed a highway safety database that can meet this need: the Highway Safety Information System (HSIS). HSIS is a roadway-based system that provides quality data on a large number of crash, roadway, and traffic variables. It uses data already being collected by States for managing the highway system and studying highway safety.