Randomisation and blinding
BLIND
Following the 4-week baseline period, eligible drivers will be randomised to intervention or control using randomly permuted blocks of varying sizes in a 1:1 ratio, stratified by study site (state) and sex (male/female). The randomisation schedule will be computer-generated by an independent statistician and stored on a password-protected database at the University of Melbourne, managed by a researcher who is not one of the investigators. It will not be possible to blind participants due to the nature of the intervention. However, chief investigators will be blinded to group allocation during the statistical analysis. Main statistical analyses will be performed blinded to group details.