Wednesday, April 2, 2014

Updated NHTSA reference for seat belt effectiveness

From: Centers for Disease Control and Prevention, Division of Unintentional Injury

Highlights from the report:
  • With all of the safety engineering improvements in cars, seat belts remain about 50% effective in reducing fatalities.
  • “Three-point belts in cars with air bags, pretensioners, and load limiters, model years (MY) 1995-2011. Belt pretensioners retract the belt almost instantly in a crash to remove excess slack. By pulling in slack, they reduce occupants’ impacts with interior surfaces and help the belt engage with the occupant to expedite “ride-down.” Peak forces are reduced because force is applied over a longer period of time. Load limiters allow belts to yield in a crash, preventing the shoulder belt from exerting too much force on the chest of an occupant.67 By MY 2007, all new cars were being equipped with pretensioners and load limiters for the driver’s and RF belts. (Cars with pretensioners but not load limiters or vice versa are not included in the analyses.) Estimated fatality reduction: 50 percent for drivers and 48 percent for RF passengers.68” (page 216)
  •  In other words, the point estimates of effectiveness for belts with pretensioners and load limiters are higher than the corresponding estimates for belts without pretensioners and load limiters in cars with air bags. NHTSA plans to issue a separate report analyzing the incremental benefit of pretensioners and load limiters. (pafe 68)
Citation: Kahane, C. J. (2013, May). Injury vulnerability and effectiveness of occupant protection technologies for older occupants and women. (Report No. DOT HS 811 766). Washington, DC: National Highway Traffic Safety Administration.