The law requiring California drivers to use hands-free devices while
talking on their mobile phones is likely to save hundreds of lives a
year, particularly when the weather is bad or roads are wet, according
to a new study released today by the Public Policy Institute of
California (PPIC).
The study estimates that after the law takes effect on July 1st,
California will experience 300 fewer traffic fatalities a year. The
state currently logs more than 4,000 traffic deaths every year.
These findings differ from previous research that has questioned the
effectiveness of hands-free laws in improving traffic safety.
Concern that phone use contributes to traffic collisions and
fatalities has prompted many industrialized nations to require that
drivers use hands-free technology while talking on the phone. In the
United States, hands-free laws are in effect in New York, New Jersey,
Connecticut, and the District of Columbia, as well as in several
cities, including Chicago and Santa Fe, New Mexico. Washington state
has a hands-free law that also takes effect on July 1st.
The PPIC study uses data collected at the state level on mobile
phone ownership and traffic fatalities to analyze the effect of laws
that mandate hands-free technology. The study finds:
- Mobile phone ownership appears to contribute to traffic deaths but
only under certain driving conditions. If the weather is bad and the
roads are wet, the effect is large. There is no observable effect in
good weather or on dry roads. - Laws requiring hands-free devices have reduced fatalities in
adverse conditions by 30-60 percent, depending on how long the law has
been in effect. - Based on the experience of New York, which in 2001 became
the first state to have a hands-free law, fatalities in adverse
conditions may remain at a lower level several years after the law
takes effect.
Previous research has found that drivers using hands-free phone
devices were just as distracted as those using hand-held phones. These
studies have relied on surveys of drivers, laboratory simulations, and
observations in vehicles specially outfitted to record a driver's
behavior and distractions. However, studies using these approaches
don't help predict the effects of a hands-free law, says Jed Kolko,
PPIC research fellow and author of the study.
"Mobile phone use can't be measured accurately at the time of a
traffic collision," he says. "A driver may hang up to avoid looking
negligent, and police can't easily access mobile phone records."
Laboratory simulations measure the effect of one kind of mobile
phone device versus another. In other words, they measure distraction
levels of a driver while using a phone.
"Drivers make real-time decisions that can't be measured in a lab,"
Kolko says. "They decide whether and when to use their phones. The
question is how these laws might change drivers' likelihood of using
any mobile phone, whether it's handheld or hands-free."
It will take more years of data to understand how hands-free laws
affect driver behavior, but Kolko suggests some possible explanations.
It may be that drivers find hands-free technology cumbersome and use
their phones less often. Or they may shift their talking minutes to
times when driving conditions are less hazardous. It's also possible
that the very fact of having such a law serves an educational function,
a warning about the dangers of talking while driving.
Despite unanswered questions about how and why mobile phones affect
traffic fatalities, the study's results suggest strategies to guide
public policy.
"Since the benefits of hands-free laws depend on driving conditions,
it makes sense to more strongly enforce the laws when driving
conditions are most difficult," says Kolko. "That can save lives."
The full report is available for free downloading.