Washington, November 7 : U.S. motorists are increasingly turning cynical about the relevance of speed limits, with many believing that they can drive more safely while speeding, according to a new study.
"So the faster you think you can go before getting a ticket, the more likely you are to think safety's not compromised at higher speeds," said Fred Mannering, a professor of civil engineering at Purdue University.
He calculated probabilities based on data from a survey of 988 motorists in Tippecanoe County, Indiana, using a series of mathematical equations in "multinomial logit models".
The researcher said that his findings seemed to be consistent with other data taken in recent years.
"For whatever reason, respect for speed limits seems to have deteriorated. A 2002 survey indicated two-thirds of all drivers reported they exceeded the posted speed limit, and roughly one-third reported driving 10 mph faster than most other vehicles. These figures are even more disturbing when you consider that they're self-reported and likely to be understating the degree of speeding problems," Mannering said.
During the survey, the Indiana participants were asked: "At what point do you feel speeding becomes a threat to the personal safety of you and your family?"
The people surveyed were given three choices: 5 mph, 10 mph or 20 mph over the speed limit.
Detailing his finding sin the journal Transportation Research Part F: Traffic Psychology and Behavior, Mannering said: "The intent of the study was to statistically assess drivers' perception of the relationship between speed limits and safety. In recent decades it has become more common for speed limits to be set for political reasons rather than for safety reasons. Consequently, the motoring public seems to have increasingly begun questioning the rationality of speed limits. This is evident in observed speed data that show the majority of drivers routinely exceed posted speed limits."
The researcher said that 21 percent of the 988 drivers surveyed thought that it was safe to drive up to 5 mph over the speed limit, 43 percent thought that it was safe to drive up to 10 mph over, and 36 percent thought it was safe to drive up to 20 mph over the speed limit.
"The new findings show that the speed enforcement is critical to motorists' safety perceptions. Let's say you think enforcement is getting lax and the speed at which you think you will get a ticket goes up from 7 mph over the speed limit to 10 mph over the speed limit. If that happens, our statistical results indicate that you would be 27 percent more likely to think you can safely drive up to 20 mph over the speed limit," Mannering said.
The survey was taken before and after a 2004 media campaign launched in the county stressing the dangers of speeding that included radio and newspaper messages.
It showed that the media campaigns studied had no statistically significant impact on drivers' views on speeding and safety.
Mannering further revealed that women who had never been stopped for speeding are 68 percent more likely to think that it was safe to drive 5 mph over the speed limit, compared to all men and other women who had been stopped for speeding.
The researcher added that both men and women drivers, who had been stopped for speeding in the last year, were about 25 percent more likely to believe that it was safe to drive up to 20 mph over the speed limit than those who had not been stopped.
"This is probably because people who habitually speed are not significantly deterred by being stopped for speeding. They might become slightly more conservative, but it doesn't slow them down to the level of people who are inherently more conservative," Mannering said.
The survey's results also suggested that people could become progressively more conservative about speeding as they aged, with a 25 year-old driver being 75 percent more likely to think it was safe to drive up to 20 mph over the speed limit than a 50 year-old driver.