Assessment Method of Effectiveness of Passenger Seat Belt Reminder

Seat belts for rear passengers are not commonly used, even though they can significantly reduce fatalities. A passenger seat belt reminder (PSBR) is installed in order to encourage seat belt use, but the effectiveness of PSBRs on the rear seat passenger has not yet been proven. We have developed a methodology to assess PSBR effectiveness. There are two pathways to encourage seat belt use. The first is that PSBR directly facilitates the passenger's use. The second is to motivate the driver request passengers to use seat belts. In the experiment, we asked participants sitting in the driver's seat to select one of five ranks of likelihood to encourage the passenger when a PSBR was presented. We also asked participants sitting in the rear passenger seat to select the rank of likelihood to use the belt voluntarily with PSBR and that to use the belt when the driver requested. The degree of likelihood was quantified by averaging the assigned percentage values to the ranks. The effectiveness of PSBR was estimated by summing the estimated percentage of passengers who used the seat belt voluntarily and the estimated percentage who had not used them voluntarily but did use them when the driver requested. We found that there was nearly a 20% increase in the use rate when a PSBR was given visually only to the driver or only to the passenger, about a 35% increase when a PSBR was given visually to both the driver and the passenger. There was a 40 to 45% increase when a PSBR was given visually directory in front of them, or a PSBR was given visually to the driver and given only auditory signal to the passenger. There was about a 55% increase when an auditory signal was given added to the visual signals to both the driver and passenger.