Adult-supervised practice in learner's permit phase has a significant but limited ability to improve safe driving...

Most U.S. states require adult-supervised practice for adolescent learner permit holders intending to obtain a driver's license before 18. However, the effectiveness of adult-supervised practice in imparting safe driving skills had been inconclusive prior to the recent development of consistent measures of adolescent learners' driving performance. We examined the relationship between the number of adult-supervised practice hours and driving performance and skill deficits for 441 learner permit holders ages 16 and 17 in Pennsylvania.

Data came from a virtual driving assessment (VDA) deployed across Children's Hospital of Philadelphia's Primary Care Network and a self-reported survey at the time of the VDA. Based on a previous study, we defined two VDA Driving Classes that describe driving performance: Major Issues or Major Issues with Dangerous Behavior Class, and Minor Issues or No Issues Class. The response options for adult-supervised practice hours were presented to adolescents as categories (none, <15 h, 15-<65 h, 65 h, and >65 h). We grouped those with 65 h with those with >65 h given the low numbers of responses in these categories. The analysis used a Chi-square test and a binomial logit to investigate how adult-supervised practice hours correspond to adolescents' VDA Driving Classes.

Chi-square test showed weak associations between VDA Driving Classes and adult-supervised practice hours. The binomial logit found that adolescents who reported zero adult-supervised practice hours were more likely to be classified into the Major Issues or Major Issues with Dangerous Behavior Class than those who reported adult-supervised practice hours. For those who reported adult-supervised practice, the differences in VDA Driving Class were not statistically significant across the three practice categories (i.e., <15 h, 15-<65 h, and $\ge$65 h). The model found no significant associations between VDA Driving Class and whether adolescent learners reported practicing with a formal instructor.

Our findings suggest that under current adult-supervised practice routines, longer practice hours have limited associations with improvements in adolescents' VDA Driving Class. Some adolescents might not be ready to deal with the more dangerous settings the VDA presents even after completing the required hours of adult-supervised practice.