7: The TRACS-CA Model for California

Starting in the 1980s and continuing on into the 1990s, individual states in the United States (US) passed various pieces of legislation aimed at furthering improvements in traffic safety. Two widely debated policies were motor vehicle occupant restraints, commonly referred to as mandatory use laws (MUL), and speed limits on rural interstate highways which states were permitted to relax in the 1987 Federal Highway Bill. Although several studies (Crandall et al., 1986; Garber and Graham, 1990; Godwin, 1992; Graham and Garber, 1984; Lave, 1985; Lave, 1992; McCarthy, 1993, 1994) have evaluated, either separately or jointly, the highway safety effects of these laws, different conclusions have been reached, particularly in regards to the higher speed limits. Not surprisingly, the research to date characterizes a variety of research methods, different time periods and geographical areas, and alternative definitions of highway safety.