Safer cars making worse drivers?

Airbags and antilock brakes may not reduce rates of traffic accidents or injuries because they encourage more aggressive driving, a US study suggests.

"Our findings suggest that the 'offset hypothesis' is occurring and that it is sufficient to counter the modest technological benefits of airbags and antilock brakes," researcher Fred Mannering, a professor of civil engineering at Purdue University, in West Lafayette, Indiana, said in a prepared statement.

The offset hypothesis predicts that consumers "adapt" to innovations meant to improve safety by becoming more relaxed and less vigilant about safety, Mannering explained.

How the study was conducted
He and his colleagues analysed five years (1992 to 1996) of data on more than 1 300 drivers in Washington state.

"We used that time period because that's when airbags started getting introduced very rapidly, and we wanted to track the same drivers over that time frame to see whether the new safety features reduced their accident and injury rate," Mannering said.

The drivers had a total of 614 accidents during the study period. Of those accidents, 16 resulted in injury. Of the 1 307 drivers, 271 had switched from a vehicle without an airbag to a vehicle with an airbag during the study period, and 270 also made the switch to antilock brakes.

Using mathematical models, the researchers calculated that airbags and antilock brakes did not affect the drivers' probability of having an accident or injury.

The findings were published earlier this year in the Journal of Risk and Uncertainty. – (HealthDayNews)

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October 2006