This meta-analysis of 67 studies was conducted to evaluate the effect of road safety campaigns on crashes. Results showed that the average effect of road safety campaigns was a 9% reduction in crashes. Road safety campaigns that included a personal message that was communicated at a point that was proximal in both space and time to the behaviour targeted by the campaign were more effective. In addition, campaigns that contained a drink-driving theme were also associated with greater crash reductions, while some of the analyses also suggested that accompanying enforcement with a short campaign duration (less than one month) were beneficial. Authors proposed that since multiple message signs were found to be effective for route guidance, it would be beneficial to examine their effect when such signs contained messages that promote safe driving behaviours.
Phillips, R. O., Ulleberg, P., & Vaa, T. (2011). Meta-analysis of the effect of road safety campaigns on accidents. Accident Analysis & Prevention, 43(3), 1204-1218.