| NHTSA Report Number DOT HS 809 199 | December 2000 | Fatality Reduction by Safety Belts For Front-Seat Occupants of Cars And Light Trucks Updated and Expanded Estimates Based on 1986-99 FARS Data
Charles J. Kahane, Ph.D.
Abstract
The National Highway Traffic Safety Administration estimated in 1984 that manual 3-point safety belts reduce the fatality risk of front-seat occupants of passenger cars by 45 percent relative to the unrestrained occupant. The agency still relies on that estimate. Shortly after 1985, the prime analysis technique for Fatality Analysis Reporting System (FARS) data, double-pair comparison, began producing inflated, unreliable results. This report develops an empirical tool to adjust double-pair comparison analyses of 1986-99 FARS data. It validates the adjustments by comparing the belt use of fatally injured people in certain types of crashes to belt use observed on the road in State and national surveys. These methods reconfirm the agency=s earlier estimates of fatality reduction by manual 3-point belts: 45 percent in passenger cars and 60 percent in light trucks. Furthermore, they open the abundant 1986-99 FARS data to additional analyses, permitting point-estimation of belt effectiveness by crash type, occupant age and gender, belt type, vehicle type, etc:
| FATALITY REDUCTION (%) BY SAFETY BELTS | | For Drivers and Right-Front Passengers | | CARS | LIGHT TRUCKS | | 3-Point Belts | 3-Point Belts | | Fatality | Min. Sampling | Fatality | Min. Sampling | | Red. (%) | Error Range* | Red. (%) | Error Range* | | IN ALL CRASHES | 45 | x | 60 | x | | BY IMPACT TYPE: | | Frontal impacts | 50 | x | 53 | x | | Side impacts | 21 | xx | 48 | x | | Nearside | 10 | xx | 41 | xx | | Farside | 39 | x | 58 | x | | Rollovers (primary) | 74 | x | 80 | x | | Rear impacts & other crashes | 56 | x | 81 | x | | BY CRASH TYPE: | | Single vehicle | 58 | x | 70 | x | | Multivehicle | 32 | x | 43 | x | | With a car | 41 | x | 57 | x | | With a light truck | 31 | x | 45 | xx | | With a heavy truck | 25 | xx | 28 | xx | | BY SEAT POSITION: | | Driver | 48 | x | 61 | x | | Right-front passenger | 37 | x | 58 | x | | BY OCCUPANT AGE: | | 5- 9 (right-front passengers) | 34 | xxx | 59 | xxx | | 10-14 (right-front passengers) | 35 | xx | 63 | xx | | 15-29 | 50 | x | 63 | x | | 30-54 | 49 | x | 64 | x | | 55-69 | 43 | x | 53 | xx | | 70-79 | 38 | x | 42 | xx | | 80 and older | 27 | xx | 30 | xxx | | BY OCCUPANT GENDER: | | Male | 45 | x | 60 | x | | Female | 45 | x | 62 | x | | BY BELT TYPE: | | Manual, in non-air-bag veh. | 45 | x | 60 | x | | MY 1975-79 | 47 | x | 49 | xx | | MY 1980-85 | 46 | x | 63 | x | | MY 1986 + | 42 | x | 60 | x | | Manual, in dual-air-bag veh. | 48 | x | 63 | xx | | 3-point automatic | 48 | xx | | 2-point automatic** | 32 | xx | | BY CURB WEIGHT (CARS): | | 2499 pounds or lighter | 48 | x | | 2500-3149 pounds | 44 | x | | 3150 pounds or heavier | 41 | x | | BY TRUCK TYPE: | | Pickup truck | | | 58 | x | | Van or SUV | | | 63 | x | *Minimum sampling error range: Ax@ denotes 2-sigma sampling error at least in the " 4-10 percentage point range (plus possible, additional, unknown non-sampling error); Axx@ = at least " 10-20 percentage points; Axxx@ = at least " 20-50 percentage points. **Effect of 2-point motorized or non-motorized torso belt, when used: includes people who used the manual lap belt and those who did not (lap belt use/non-use is often unknown in FARS data). Note: all of the other effectiveness estimates in these tables are limited to front-outboard occupants of vehicles with 3-point belts, and exclude automatic 2-point belts. |
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