Distracted driving: a silent killer?

By Chris McCahill

Blame Apps,” read a New York Times headline from last year, referring to the recent spike in traffic deaths. Representatives from the Property Casualty Insurers Association of America and the National Highway Traffic Safety Administration called distracted driving a “serious public safety concern” and a “crisis.” Yet there still doesn’t seem to be any compelling evidence linking the surging death rate to distracted driving.

That’s not to say drivers aren’t distracted. AAA reported earlier this month that in-vehicle touchscreens and voice activated systems could pose new problems. According to their report, led by researchers at the University of Utah, many of these new technologies place “high” or “very high” demand on drivers, with some tasks taking 40 seconds to complete, on average.

As worrisome as that is, the newest numbers from U.S. DOT—released the same week as the AAA report—show deaths related to distracted driving dropped 2.2 percent in 2016, while traffic deaths increased 5.6 percent overall.

Zendrive, a tech startup that provides smartphone-based safety monitoring, has also targeted distracted driving, citing evidence of their own. Earlier this year, they analyzed three months of data from three million of their users—the largest data set of its kind—and found that drivers use their phones on 88 percent of trips, averaging 3.5 minutes of use per hour. They also released an interactive map rating school zone safety throughout the U.S., based on their data.

Again, however, the link between distracted driving and crashes isn’t clear. State-level estimates of distracted driving from Zendrive can’t explain the differences in fatal crash rates (Figure 1). Better data—for example, reliable data showing increases in distracted driving over time—could reveal a stronger trend, but it’s surprising that trend is so elusive.

Figure 1. Distracted driving versus fatal crash rates at the state level. Data sources: U.S. DOT, U.S. Census, and Zendrive.]

If it’s not distracted driving, why are our roads so unsafe?

The most obvious explanation is the amount that we drive. The average number of vehicle miles traveled per person helps explain the sudden drop and the comparable uptick in traffic deaths since 2005. VMT rates also explain most of the difference in traffic deaths among states (Figure 2).

Figure 2. VMT rates versus fatal crash rates at the state level. Data sources: U.S. DOT, U.S. Census, and Zendrive.

As in 2015, speeding, drunk driving, and not wearing seatbelts factor into many traffic deaths (more than 10,000 each in 2016) and pedestrian deaths continue to rise at an alarming rate (nearly 6,000 in 2016, a 9 percent increase).

Chris McCahill is an Associate Researcher at SSTI.