Phone use and speeding have emerged as dangerous partners on U.S. roads

A new study by the Insurance Institute for Highway Safety (IIHS) has shattered the widespread assumption that drivers only reach for their smartphones during calm, slow-moving traffic. The data revealed the opposite: the more a driver exceeds the speed limit, the more frequently they simultaneously handle their phone. Two risky behaviors, each of which independently increases the likelihood of a crash, turned out to be far more closely linked than previously thought.

Phone use while driving is prohibited in 49 out of 50 states, as it diverts visual attention and occupies at least one hand. IIHS focused specifically on the intersection of these two violations, and the results were alarming.

Every five miles over the limit adds more screen time

The relationship between speeding and phone activity varies depending on road type:

• On freeways and limited-access roads (freeway, interstate), the share of time spent handling a phone increased by 12% for every additional 5 mph over the speed limit.
• On arterial and intercity roads, where intersections, traffic lights, and roundabouts are more common, the increase was 3% for the same increment in speed.

Logic might suggest the opposite: the higher the speed, the more dangerous it is to be distracted. Yet it is precisely on monotonous high-speed stretches that drivers feel more confident and reach for their screens. It therefore comes as no surprise that South Carolina was entirely justified in passing a law requiring “hands-on-the-wheel.”

Higher speed limits amplify the effect

A separate layer of data showed that the posted speed limit itself influences the scale of the problem. On limited-access roads where 70 mph is permitted, the increase in phone use for each additional 5 mph was 9% higher than on comparable roads with a 55 mph limit. On roads without access restrictions, a similar pattern emerged: relative to zones with 25–30 mph limits, the “phone-use increase” was 3% greater at 45–50 mph limits and 7% greater at a 55 mph limit.

Three explanations for why violations go hand in hand

IIHS proposed several explanations for the observed correlation:

• Risk-taking propensity as a trait. Drivers who regularly speed are also more likely to use their phones while driving. Both types of violations naturally gravitate toward the same behavioral profile.
• High-stress time windows. Research shows that during rush hour and school drop-off/pick-up times, both speeding and phone use rise simultaneously, even though these spikes are formally independent of each other.
• Road “cues.” Free-flowing traffic, the absence of pedestrians, and long gaps between traffic lights create a false sense of safety, prompting drivers to become distracted.

What drivers are actually doing with their phones at speed

CMT data makes it possible not only to record the fact of device handling but also to indirectly assess the nature of the activity. Analysts identify several typical scenarios of smartphone use while driving:

• Messaging and reading notifications.
• Navigation and switching routes.
• Watching short videos and browsing social media.
• Calls without a hands-free device, holding the phone to the ear.
• iGaming: betting, slots and live card games.

The last item deserves special attention. The mobile gambling industry is growing faster than most segments of entertainment apps, and a portion of sessions occur while the user is behind the wheel. When we decided to visit site dedicated to reviews of Asian table games such as Sic Bo, as well as portals with Andar Bahar reviews for the Indian market, some interesting figures appeared in the statistics sections of those sites: a notable share of players launched Andar Bahar rounds during daytime hours that coincide with peak road traffic. A similar pattern is observed across other gambling entertainment available on mobile devices.

All of this supports the IIHS conclusion about behavioral profile: risk-taking propensity manifests across multiple dimensions, and a monotonous road simply lowers the internal barrier against yet another distraction.

Nearly 600,000 trips under a digital microscope

The study was based on aggregated data from safe-driving apps that insurance companies offer clients in exchange for a potential discount on their insurance premium. The data was provided by Cambridge Mobile Telematics (CMT). The sample covered nearly 600,000 trips across the USA between July and October 2024.

The analysis included trips lasting more than 18 minutes that involved at least two minutes of travel on an interstate. Data from Alaska, California, Hawaii, and New York were excluded from the sample, as were all segments where speed was more than 5 mph below the limit, in order to minimize the influence of heavy congestion.

How phone handling was detected

The methodology for detecting contact with the device relied on three elements:

• The phone was considered “in hand” if the built-in gyroscope registered significant rotation while the screen was unlocked.
• The metric was calculated as the proportion of handling time relative to total trip duration.
• Speeding was determined by comparing the GPS track against a speed limit database, after which statistics were assessed by road type and speeding range.

From insurance discounts to smart cameras

Insurer telematics programs incentivize careful driving, but, as the study itself demonstrates, they are unable to eliminate the problem entirely. IIHS advocates expanding automated enforcement cameras capable of simultaneously tracking both speed and phone use. Such cameras have been operating in China and several other countries for a number of years.

The study’s abstract also mentions an engineering approach: measures that increase the “perceived complexity” of the road environment can help sustain driver attention. Specific solutions, however, are not detailed in the paper.

The digital trail and the limits of monitoring

Research at this scale has become possible thanks to the proliferation of apps that collect smartphone telemetry: speed, maneuvers, time of day, and instances of device use. This opens new horizons for road safety analysis, while simultaneously fueling debate about the acceptable boundaries of driver behavior monitoring.

The IIHS data make it unambiguously clear that phone use does not decrease as speed increases but, on the contrary, accompanies speeding — particularly on fast-moving freeways. The Institute calls for the parallel development of technological and engineering measures aimed at reducing the risk of crashes caused by this dangerous pairing.