Study shows police reports undercount cellphone use before crashes

A new study from the Insurance Institute for Highway Safety that draws on telematics data confirms that far more drivers are using cellphones in the lead-up to crashes than is reflected in police reports.

The data — which come from safe-driving apps that drivers voluntarily enroll in — show that cellphone use prior to crashes is undercounted in police reports by a factor of at least 7.

“It’s widely accepted that police reports often fail to capture the role of cellphones in crashes. Many smartphone functions are hard for a witness to see, and drivers are reluctant to admit being distracted,” IIHS President David Harkey said. “Telematics are allowing us to understand the true magnitude of the problem.”

IIHS researchers examined anonymized cellphone data from Cambridge Mobile Telematics (CMT) for the study. They found that drivers enrolled in safe-driving programs that rely on the CMT platform were using their cellphones in the 30 seconds prior to impact in 7% of single-vehicle crashes and 8% of two-vehicle crashes. Police reports for the same crashes recorded cellphone use in less than 1%.

Those numbers include drivers whose screens were unlocked for any reason, including navigation. However, telematics data show the problem of undercounting is nearly as severe when only physical manipulation of the phone and hand-held and hands-free calls are considered.

Beyond talking and texting

Anything that takes the driver’s focus away from driving — including eating, talking or even daydreaming — increases crash risk. But the risk is more severe for more complex tasks that take the driver’s eyes away from the road. Looking away from the road for just two seconds doubles the risk of a crash or near-crash event.

The trend toward screen-based smartphone apps makes that especially worrisome. Though voice commands make old-school actions like calling and texting safer, gaming and social media apps offer new temptations. In many jurisdictions, the laws have yet to catch up.

“The apps may be new, but the danger isn’t,” IIHS Research Scientist Aimee Cox, the study’s lead author, said. “Any phone use that takes a driver’s eyes off the road can increase crash risk.”

To address the uses of modern smartphones, 21 states now prohibit drivers from holding phones. These laws are easier to enforce than those that ban specific behaviors, such as texting and hand-held calls; a police officer just needs to see a phone in the driver’s hand, not what it is being used for. IIHS research shows that these more sweeping laws are more effective.

Linking telematics data to police reports

To determine how often smartphone use is overlooked in police reports, IIHS researchers worked with CMT to link crashes recorded by safe-driving apps to police-reported crashes in four states between 2021 and 2024. Since police reports do not always record crash times and locations with perfect precision, crashes that occurred within the same 15-minute window and within the same one-mile radius were determined to be a match. This generated a sample of nearly 17,000 linked crashes.

Along with detecting crashes, CMT’s platform can identify when and how the driver uses their phone. To monitor distraction, the company tracks hand-held calls, hands-free calls, and manipulation or handling of the device. It also logs times when the screen is unlocked for something passive like Google Maps or YouTube, though CMT does not use this measure in its own studies of distraction.

CMT does not track what specific apps are used. The researchers also didn’t have a way to determine whether the cellphone user was considered at fault in the crash or whether distraction caused the incident.

Looking only at active cellphone use, the researchers found that drivers tapped, swiped or otherwise manipulated their phones before hundreds of crashes, while hands-free and hand-held calls were comparatively rare. Police reports noted almost none of this activity.

Driver cellphone use before crashes as captured by telematics data versus reported by police

Note: For two-vehicle crashes, telematics data captured and recorded behaviors of both drivers when both were users of apps supported by CMT.

Passive use is also common

For a more complete picture, the researchers also looked at how often the telematics data and police reports noted passive cellphone use. For the telematics data, this meant any time that the driver was not touching the device but the screen was unlocked. The police report categories used for comparison were broader and included behaviors such as “other activity with an electronic device,” “other electronic device — navigation, radio, etc.” and “cell/mobile device use — unknown.”

As shown in the table, passive use was about as common as active use in the 30 seconds prior to impact.

Navigation apps may have accounted for much of that passive activity. But nearly 25% of drivers who participated in a separate IIHS survey admitted to watching a video on their phone while driving at least once in the previous 30 days.

And even navigation apps can increase crash risk if drivers are looking away from the road ahead for too long. In a U.S. Department of Transportation study that tracked drivers during their everyday trips, many of the longest glances away from the road before crashes and near crashes were directed toward the center stack, a common location for cellphone mounts.

The telematics data offer no way of knowing how long drivers in the study sample spent looking at their unlocked screens before they crashed — if they were looking at them at all.

It’s also impossible to know how many additional drivers were using similar apps with CarPlay or Android Auto. Such use does not require the phone’s screen to be unlocked.

Even when police and telematics both indicated cellphone use, they usually didn’t agree about the type of use. Police reports noted the same activity as the telematics data in only three out of nearly 17,000 linked crashes.

That mismatch could be one key to the broader problem of underreporting. Police officers may not always be able to determine exactly how a driver was using a cellphone after a crash. That challenge is compounded by the fact that in many jurisdictions, only certain types of cellphone use are illegal. But if other, legal behaviors go unreported, lawmakers may be slow to realize that they also increase crash risk. Telematics data could help address that disconnect.