| Sixteen- and seventeen-year-old drivers have higher crash rates than any other age group. Graduated driver licensing (GDL) programs, which are specialized driver licensing systems for beginner drivers, have been implemented in most U.S. states to reduce young teen drivers' exposures to high-risk driving situations while they gain driving experience. Driver fatal crash involvements for all U.S. states from 1986--2007 were analyzed using Poisson regression models to estimate the associations of GDL programs with 16-, 17-, 18-, and 19-year-old crash incidences. GDL programs were reliably associated with 16--26% lower driver fatal crash incidence for 16 year olds, but 10--12% higher incidence for 18 year olds, dependent upon the number of license restrictions included during the intermediate licensing stage. GDL programs with two license restrictions during the intermediate licensing stage were marginally associated with 9% lower 17-year-old driver fatal crash incidence. The benefits of GDL programs in terms of reducing 16- and 17-year-old driver fatal crash involvements were found to outweigh the increased involvements among 18 year olds associated with such programs. Overall, 544 fewer net 16--19-year-old driver fatal crash involvements during the 12-year period since the first U.S. GDL program was implemented are attributable to having specialized teen driver licensing systems. The majority of the net crash reduction (470 involvements) is attributable to implementing three-stage GDL programs. At least one calibration for each GDL program core component, except supervised driving hours, was associated with a net decrease in 16--19-year-old driver fatal crash involvements. The calibrations of the GDL program core components associated with the largest net 16--19-year-old driver fatal crash involvement savings are: (a) a minimum learner stage entry age of 16 years; (b) a minimum learner permit holding period of 9--12 months; (c) no minimum number of required supervised driving hours; (d) an intermediate licensing stage starting at age 16.5--17 years; (e) a nighttime driving restriction starting at 11:00 pm; (f) a passenger restriction allowing no more than one teen passenger that lasts for 6 months or longer; and (g) unrestricted licensure starting at age 17--17.4 years. |
