Background The learner stage of graduated driver licensing (GDL), when teenagers are supervised by an adult driver, represents an opportunity to develop skills that could confer a safety benefit during their years of independent driving. This paper describes the design of a teenage driving study, which aims to evaluate the impact of a smartphone application, the ‘DrivingApp,’ to increase the quantity and improve the quality of supervised practice driving.

Methods This longitudinal intervention study of teenage drivers and a parent/guardian spans the final 6 months of the learner licence and the first year of independent driving. Participants will be assigned to experimental or control groups using block allocation. Parent–teenage dyads assigned to the intervention arm will receive information about their practice driving via a smartphone application, including miles driven and total drive time. Baseline and monthly surveys will be administered to both experimental and control participants to measure the outcome measures during the learner stage: (1) practice driving amount, (2) consistency and (3) variety. Outcomes during independent driving are (1) self-reported number of attempts at the driving test and (2) number of crashes during the first year of independent driving.

Discussion Improving the quality of teenagers’ supervised practice driving is an unmet research need. This study will contribute to the evidence about what can be done during the learner period of GDL to maximise teenage drivers’ safety during the first years of independent driving, when crash risk is highest.