On Tuesday, the National Transportation Safety Board (NTSB) called for a nationwide ban on texting and calling behind the wheel. Many individual states and municipalities have their own prohibitions on cell-phone use while driving, but the new ban seeks to outlaw all non-emergency calls and texts by every driver in America. Coincidentally, on the same day, a new analysis of past data on distracted driving found that the crash risk may have been overstated.
Researchers at Wayne State University School of Medicine in Detroit looked at two influential studies on distracted driving and car crashes, and concluded that the papers’ methodology was problematic. One study was published in 1997 by Canadian researchers; the other was from Australia in 2005, finding that cell phone use by drivers raised the risk of a car crash by four times.
The two studies recruited people who had been in a crash, and then used their cell phone billing records to compare their phone use during the time of the crash with their use during the same time period the week before. The previous-week comparison period was called the “control window.” The problem, according to Richard Young, the lead author of the new analysis, published in Epidemiology, is that while the researchers asked people whether they had driven during the control window, they didn’t ask how much they drove.
Many drivers have sporadic schedules that make week-to-week comparisons difficult. And if people had been driving less the week before the accident, then they would have naturally had less chance of an accident and less cell phone use behind the wheel.
“Earlier … studies likely overestimated the relative risk for cell phone conversations while driving by implicitly assuming that driving during a control window was full-time when it may have been only part-time,” wrote Young.
Taking into account this limitation of the previous research, Young and his team carried out their own study: they tracked the day-to-day driving habits of 439 drivers over 100 days. The days were grouped into pairs — a “control” day paired with a “crash” day — just to see how people’s driving differed between days.
The researchers found little consistency. In fact, Young found that the overall frequency of driving on control days was 75% less than on crash days. Applied to the previous data, Young surmises that the association between cell phone use and crash risk would disappear.
Still, that doesn’t mean you should start whipping out your iPhone on the highway. Although you shouldn’t need a study to tell you that driving while texting or playing Angry Birds is obviously very dangerous, there’s no shortage of other data backing that up. Reported Reuters Health:
Fernando Wilson, an assistant professor at the University of North Texas Health Science Center who was not involved in the analysis, said that the two earlier studies may well have overstated the risk.
But a number of other studies designed in different ways suggest that cellphone use — and especially texting — is indeed hazardous on the road, he added.
In his own study published last year, Wilson looked at information from a government database tracking deaths on U.S. public roads. After declining between 1999 and 2005, deaths blamed on distracted driving rose 28 percent between 2005 and 2008.
“I don’t think this study is going to change the conversation about distracted driving,” Wilson told Reuters Health. “Most of the conventional thinking is that we need to do something to reduce it.”
Indeed, the ban recommended by the NTSB would prohibit all driver use of cell phones and other portable electronic devices, except in emergencies, and applies to both hands-free and handheld phones. It goes far beyond existing state laws restricting texting and calling while driving, which are currently in place in at least 35 states.
Despite the proliferation of state laws, the AP reports that the problem of texting while driving is increasing, according to National Highway Traffic Safety Administration data: about 20% of American drivers, including half of drivers aged 21 to 24, say they’ve texted or sent emails while driving. The AP reports:
At any given moment last year on America’s streets and highways, nearly 1 in every 100 car drivers was texting, emailing, surfing the Web or otherwise using a handheld electronic device, the safety administration said. And those activities spiked 50 percent over the previous year.
The NTSB made its recommendation in connection with a highway pileup near Gray Summit, Mo., in August 2010. An investigation of the deadly accident found that a 19-year-old driver of a pickup had sent or received 11 texts in the 11 minutes immediately before plowing into the rear of a tractor truck that had slowed for highway construction.
A school bus then hit the pickup, and another school bus slammed into the first bus. The pickup driver and a 15-year-old student on one of the school buses were killed, and 38 others were injured.
The board has previously called for bans on texting and cell phone use by commercial truck and bus drivers and novice drivers, but this is the first time it has recommended a ban for all adult drivers on the road. Although the board doesn’t have the power to impose restrictions, the AP reported, its recommendations are considered seriously by lawmakers and federal regulators.