New research from the Virginia Tech Transportation Institute (VTTI) suggests that drivers are less likely to get into a crash if they use hands-free electronic devices rather than handheld ones to make calls and perform other tasks, while still keeping their hands on the wheel and eyes on the road.
Many newer cars feature integrated hands-free interfaces for phone calls, navigational use and other tasks, that are intended to allow drivers to keep both hands on the wheel and stay focused on driving.
The goal of the VTTI project was to determine the extent to which crash risk could be affected by primarily mental behaviors, known as ‘cognitive distractions’. These distractions occupy the mind, but do not require the driver to look away from the road or remove their hands from the wheel. Examples include interacting with a passenger, singing in the car, talking on a hands-free cell phone, and dialing on a hands-free phone via voice-activated software.
Using video and other sensor data from the Federal Highway Administration’s (FHWA) Second Strategic Highway Research Program (SHRP2) naturalistic driving study, the largest light-vehicle study of its kind ever conducted, the VTTI research team analyzed video footage of 3,454 drivers, 905 crashes (including 275 more serious crashes), and 19,732 control periods of ‘normal driving’ for instances of cognitive distraction. For comparison, they also studied examples of drivers performing visual and manual activities, such as texting on a hand-held phone or adjusting the radio.
Drivers who used a hand-held phone increased their crash risk by 2 to 3.5 times compared to model drivers, defined as being alert, attentive and sober. When a combination of cognitive secondary tasks was observed, the crash risk also went up, although not to nearly the same degree. In some cases, hands-free cell phone use was associated with a lower crash rate than the control group. None of the 275 more serious property-damage and injury crashes analyzed were associated with the use of hands-free systems.
“Any activity that places either visual or manual demands on the driver, texting, browsing or dialing a hand-held phone, for instance, substantially increases crash risk. However, our recent study has found that the primarily cognitive secondary task of talking on a hands-free device does not appear to have any detrimental effects,” said Tom Dingus, director of VTTI and the principal investigator of the study.
“There are a number of reasons why using a hands-free device could keep drivers more engaged and focused in certain situations. One is that the driver looks forward more during the conversation. Although engaging in the conversation could cause a small amount of delay in cognitive processing, the driver is still more likely be looking in the direction of a precipitating event.
“The phone conversation could also serve as a countermeasure to fatigue on longer road trips. Our research has shown consistently that activities requiring a driver to take their eyes off of the forward roadway, such as texting or dialing on a handheld phone, pose the greatest risk.”