“Primary enforcement” of distracted driving laws leads to lower death rates in states with texting laws, while secondary enforcement does not, according to a new study.
Meanwhile, another research team found that California’s handheld device failed to lower the number of vehicle crashes in its first six months.
The study on primary enforcement should bolster state lawmakers seeking to give police the ability to stop and cite distracted driving offenders.
“Very little is known about whether laws banning texting while driving have actually improved roadway safety,” said researcher Alva Ferdinand of the University of Alabama at Birmingham.
She was motivated by “considerable variation” in state distracted driving laws, seeking to determine “which types of laws are most beneficial in improving roadway safety.”
Primary enforcement means that police have the ability to pull over violators of distracted driving laws, while secondary enforcement means another infraction — such as weaving or driving too slow — must be observed before a stop. Most states with texting laws call for primary enforcement, but four do not.
In states with primary texting laws, Ferdinand found “a 3 percent reduction in traffic fatalities among all age groups, which equates to an average of 19 deaths prevented per year” in those states.
Most effective were primary texting laws that targeted young drivers. They had “an associated 11 percent reduction in traffic fatalities among this age group in states with such bans.”
States with secondarily enforced restrictions did not see any significant reductions in traffic fatalities, according to Ferdinand’s analysis of federal Fatality Analysis Reporting System data collected between 2000 and 2010.
The UAB distracted driving study found that states that banned use of handheld cell phones for all drivers saw reductions in fatalities while texting laws were most effective with novice drivers.
“Handheld bans appear to be most effective for adults,” she said.
Secondary enforcement laws sometimes result from compromises in the legislative process, a recent example being Florida’s texting law. Some states have upgraded their enforcement to primary after widespread complaints from law officers that secondary enforcement equals no enforcement.
The California study, which has been published previously, researchers at the University of Colorado Boulder “didn’t find any statistical evidence of a reduction” in traffic crashes in the six-month period following enactment of the state’s handheld cell phone law.
California’s cellphone driving ban went into effect July 1, 2008, with primary enforcement. Highway Patrol numbers from the first six months of the law’s implementation did show a 20 percent reduction in fatalities and collisions, the law’s sponsor reported in 2010, but the comparison period was spread over several years.
“Our results suggest that simply banning hand-held cellphone use may not produce the desired increase in traffic safety,” Colorado researcher Daniel Kaffine said.
Possible reasons given for the lack of a decline included lack of compliance with the distracted driving law; distractions from hands-free devices such as Bluetooth headsets; and an overstatement of risks from cell phone use while driving.
“Disentangling these effects will be useful for policymakers in other states who are considering policies to address distracted driving,” Kaffine said.
The two studies add to a growing body of research that’s split on the effectiveness of distracted driving laws.
Kaffine told HandsFreeInfo: “The evidence on bans is pretty mixed — some papers find evidence that these bans are effective and some find that they’re not.”
Unfortunately, he said, “there isn’t a silver bullet” for researchers trying to find out if distracted driving laws work. “So what you see is a number of varying approaches” to studies.
“Factors like changes in how we use our phones, who’s using phones, and who’s driving in the first place have to be dealt with by researchers,” he said.
- Read more about texting & driving research studies.
