HazAPP: Study protocol of a randomized controlled trial to enhance parental instruction of teens' hazard anticipation skill during the learner phase of licensure.

backgroundDespite very low crash rates during the learner phase of supervised licensure, teen driver crash rates immediately spike at the onset of independent licensure. A large percentage of driving errors among newly licensed teens is attributed to a failure to recognize roadway hazards. Parents serve as the primary instructor of teens' driving under the learner phase of licensure, yet existing literature indicates that parents do not regularly engage in instruction on how to anticipate and respond to potential roadway hazards. The goal of the current randomized control trial, as reported in this study protocol paper, was to evaluate a web-based, parent-focused teen driving intervention, the Hazard Anticipation Program for Parents (HazAPP), to improve parental instruction of teens' ability to anticipation hazards.

methodsTeen drivers in the learner phase of licensure (ages 14 to 17) and their parents were recruited via email listservs, postings and flyers to area schools, social media postings, and word of mouth. Pending eligibility screening and consent, dyads were randomly assigned to either the intervention or control arm of the study. Parents in the intervention arm of the study engaged in an online training program that sought to help parents better communicate their expert hazard anticipation knowledge to their teens. The training was two-fold: parents engaged in a web-based program that provided insights on how to best communicate with their teen when encountering hazards on the roadway, followed by a guided joint task that allowed parents to practice these skills with their teen in a safe environment by watching videos of hazards unfold. The study took place over two study visits approximately 4 weeks apart. At Visit 1, parents and teen completed questionnaires and engaged in an acclimation drive to ensure dyads would not experience motion sickness in simulated driving. All participants were then given a dashcam to record four naturalistic driving sessions before returning for Visit 2 where participants completed a study drive with 17 embedded hazards. Driving sessions (simulated and naturalistic) will be coded for content to determine intervention efficacy for improving parental instruction. Primary outcomes will include parental use of functional driving instructions, hazard identification, hazard anticipation communications, if these communications occurred before hazards become critical and if they contain elements of motivational interviewing, which were modeled in the web-based program. Secondary outcomes of teens' driving performance will include hard braking events and lane changes in response to hazards and parental instructions.

trial registrationThis study (NCT06611241) was registered on Clinicaltrials.gov on September 2, 2024 (https//clinicaltrials.gov/study/NCT06611241) and last updated on February 9, 2026. This protocol was developed using the SPIRIT guidelines and checklist. The version reported here is the first protocol version that was submitted on September 2, 2024.