Using a hands-free mobile phone kit when driving causes the same level of impairment as being over the alcohol limit, a US study has shown. Researchers from University of Utah also found no difference in the degree of impairment suffered by drivers using a handheld compared with a hands-free mobile.
Both affected driving ability in the same way as being over the (US) blood-alcohol limit of 0.08 per cent. This "calls into question driving regulations that prohibit hand-held cell phones and permit hands-free cell phones", according to the researchers.
Based on statistical analysis, the researchers estimate a driver using a mobile phone or hands-free kit is five times more likely to crash than an undistracted driver.
Under the Road Traffic Act 2006, which came into force last week, driving while using a handheld mobile is an offence that attracts two penalty points if a motorist pays the fixed charge. On conviction this is raised to four penalty points and a fine of up to €2,000. Driving while using a hands-free kit is legal.
Psychologists at University of Utah who conducted the three year study found: "People are as impaired when they drive and talk on a cell phone as they are when they drive intoxicated at the legal blood-alcohol limit" of 0.08 per cent, which is the minimum level that defines illegal drunken driving in most US states.
Psychology Professor and study author David Strayer, said if legislators want to address the problem of driver distraction they should consider banning all mobile phone use by drivers.
To test the effect on drivers of using a mobile, 40 participants carried out four tests, each using a PatrolSim driving simulator. First they drove undistracted, then while talking on a hand-held mobile phone to the researchers and once again while talking using a hands-free kit.
Finally they used the simulator after drinking vodka and orange juice producing a 0.08 per cent blood-alcohol level.
The participants had to follow a pace car that braked intermittently as if approaching lights or slower traffic. Compared with undistracted drivers the study found that drivers talking on a hand-held or hands-free mobile had 9 per cent slower reaction time to brake, and were 24 per cent more likely to keep constantly changing their distance to the car in front.
Three of the drivers talking on their phones crashed into the pace car.
After consuming alcohol the participants drove more slowly but more aggressively, braking later and harder to avoid collision. The researchers used 25 men and 15 women aged 22 to 34 who were licensed drivers and social drinkers. Two-thirds admitted to using a mobile while driving.
The results were published in the latest issue of Human Factors: The Journal of the Human Factors and Ergonomics Society. The authors decided to scientifically measure the impact of mobile phone use after another US study of 699 drivers involved in crashes found 25 per cent had used their mobile during or just before the crash.
