Effectiveness of Seat Belts in Reducing Injuries

This study estimated the effectiveness of seat belts in reducing injuries and estimated the associated economic benefits using state of Kansas data. The estimation process included three stages. In the first stage, seat belt effectiveness in reducing injuries to motor vehicle occupants was estimated. Crash data from Kansas Accident Reporting System (KARS) database was used to accomplish this estimation process. Seat belt effectiveness was estimated using logistic regression method. The associated results were then compared with estimated values obtained from double pair comparison method. The two vehicle type groups considered in the study were limited to passenger cars group, and other passenger vehicle group that included pickup trucks and vans. In the second stage, the estimated seat belt effectiveness values resulted from the first stage were subsequently used to estimate potential injury reductions due to increased seat belt usage. In the third stage, obtained injury reduction values were converted into economic values by assigning economic costs for each injury type severity. According to the obtained estimations, seat belts are 56% effective in preventing fatal injuries when used by passenger car front seat occupants. In the other passenger vehicle group that included vans and pickups, seat belts were found to be 61% effective in preventing fatalities. The seat belt effectiveness, in reducing incapacitating and non-incapacitating injuries, was respectively found to be 53% and 55% for passenger cars group, and 52% and 51% for other passenger vehicle group. Based on the analysis conducted in this study, it was found that 1% incremental increase in current seat belt usage rate could annually save about $13 million to the state of Kansas. If seat belt usage in Kansas reaches the national average rate of 82% (2005 value), the resulted annual economic savings are estimated to be around $260 millions.