Study Finds Drivers Use Phones More Frequently When Speeding, IIHS Reports

Speeding and phone use while driving remain persistent hazards on the road, despite widespread awareness of the risks. A new study from the Insurance Institute for Highway Safety (IIHS) suggests that drivers often engage in both behaviors simultaneously, challenging previous assumptions about when and where phone use is most prevalent.

“Until now, safety experts believed drivers used their cellphones most at slower speeds,” said David Harkey, IIHS president, in a press release. “But data from insurance companies’ safe-driving apps show that, in free-flowing traffic, the opposite is true.”

The study leveraged data from insurer-backed safe-driving apps, which track driver behavior to offer potential cost savings. These apps use a phone’s sensors and GPS to monitor speed, acceleration, braking, location, and time of day. Phone use was detected based on significant rotation registered by the phone’s gyroscope while the screen was unlocked, while speeding was identified by matching GPS data to a speed-limit database.

Key Findings from the IIHS Study

Phone Use Increases with Speeding

Researchers analyzed nearly 600,000 trips taken between July and October 2024 across all U.S. states except Alaska, California, Hawaii, and New York. Only trips lasting at least 18 minutes—with at least two minutes on an Interstate highway—were included. Periods where drivers traveled 5 mph or more below the speed limit were excluded to focus on free-flowing traffic.

The data revealed that phone use rose by 12% for every 5 mph over the speed limit on limited-access highways. On other roads, the increase was smaller—3% per 5 mph over the limit. The IIHS attributed this difference to the need for drivers to frequently interact with traffic lights, intersections, and stop signs on non-highway roads.

Higher Speed Limits Correlate with Increased Phone Use

Drivers were also more likely to use their phones on roads with higher speed limits. On limited-access highways with a 70-mph limit, researchers observed a 9% larger increase in phone use per 5 mph over the limit compared to similar roads with a 55-mph limit. On other roads, the increase in phone use was 3% larger on roads with a 45-50-mph limit than on roads with posted limits between 25 and 30 mph, and 7% larger on roads with a 55-mph limit.

Possible Explanations for the Trend

The IIHS highlighted several potential factors contributing to this behavior:

• Risk-taking tendencies: Drivers who engage in one risky behavior, such as speeding, may be more likely to engage in others, like phone use.
• Stress: Previous studies have linked stress to both increased phone use and speeding, suggesting a possible connection.
• Perceived safety: Drivers may view higher-speed, limited-access roads—with lighter traffic and fewer pedestrians—as safer environments to use their phones.