In the cell phone vs drunk driving battle, which is more dangerous?
Cell Phone vs Drunk Driving
Dr. Frank Drews and his colleagues at the University of Utah decided to find out. So they conducted an experiment. Spoiler alert! Drivers who talk on either handheld or hands-free cellular phones are as impaired as drunken drivers.
The study reinforced earlier research showing that hands-free cell phones are just as distracting as handheld cell phones
“If legislators really want to address driver distraction, then they should consider outlawing cell phone use while driving.” says Dr. Drews.
Both handheld and hands-free cell phones impaired driving, with no significant difference in the degree of impairment. That calls into question driving regulations that prohibited handheld cell phones and permit hands-free cell phones.
This controlled laboratory study included 25 men and 15 women ages 22 to 34. They were social drinkers (three to five drinks per week) recruited via newspaper advertisements. Two-thirds used a cell phone while driving. The study paid each participant for their 10 hours in the study.
The driving simulator has a steering wheel, dashboard instruments, and brake and gas pedals. The driver is surrounded by three screens showing freeway scenes. Each simulated daylight freeway drive lasted 15 minutes. The pace car intermittently braked to mimic stop-and-go traffic. Drivers who fail to hit their brakes eventually rear-end the pace car. Other simulated vehicles occasionally passed in the left lane, giving the impression of steady traffic flow.
Each study participant drove the simulator during three sessions. They were (1) undistracted, (2) drunk, or (3) talking to a research assistant on a cell phone. Each was on a different day.
The simulator recorded driving speed, following distance, braking time and how long it would take to collide with the pace car if brakes were not used.
The researchers used a device to measure blood-alcohol levels.
The study found that compared with undistracted drivers:
- Motorists who talked on either handheld or hands-free cell phones
- Drove slightly slower.
- Were 9% slower to hit the brakes.
- Displayed 24% more variation in following distance as their attention switched between driving and conversing.
- Were 19% slower to resume normal speed after braking.
- Were more likely to crash. (Three participants rear-ended the pace car. All were talking on cell phones. None were drunk.)
Drivers drunk at the 0.08 blood-alcohol level
- Drove a bit more slowly than both undistracted drivers and drivers using cell phones.
- Were more aggressive.
- Followed the pace car more closely.
- Were twice as likely to brake only four seconds before a collision would have occurred.
- Hit their brakes with 23% more force.
Neither accident rates, nor reaction times to vehicles braking in front of the participant, nor recovery of lost speed following braking differed significantly.
Lack of Accidents
The lack of accidents among the study’s intoxicated drivers may have been because it was conducted in morning hours when participants were well rested. However, most drunken driving accidents occur late at night when drivers are fatigued and their average blood alcohol content (BAC) levels are also twice the legal .08 level used in the research.
“Fortunately, the percentage of drunk drivers at any time is much lower.” said Dr. Drews. “So it means the risk of talking on a cell phone and driving is probably much higher than driving intoxicated because more people are talking on cell phones than driving while drunk.”
Cell phone users are about 5.36 times more likely to get in an accident than undistracted drivers. Other studies have shown the risk is about the same as for drivers with a 0.08 blood-alcohol level.
The researchers are not trivializing drunken driving. They oppose both driving while intoxicated or while using a cell phone.
The Federal Aviation Administration supported the study. It’s interested in impaired attention among pilots. Human Factors: The Journal of the Human Factors and Ergonomics Society published the report.
Readings: Cell Phone vs Drunk Driving
Espejo, R. Cell Phones and Driving. Farmington Hills, MI: Greenhaven, 2015.
Zuckerman, M. Cell Phone Use and Distracted Driving Laws. Denver: CO Leg Coun, 2014.