Concern is mounting about the effects of phone use and texting while driving
October, 2016
How frequently do drivers talk on the phone or text behind the wheel?
A 2015 national observational survey found that 4 percent of drivers stopped at intersections were talking on hand held phones at any moment during the day. Combining this observational data with self reported data on hand held and hands free phone use, the federal government estimates that 7 percent of drivers were having phone conversations during any moment of the day. This rate has declined 23 percent since 2013 after doubling between 2000 and 2005.
Institute research examined the cell phone use of 105 Virginia drivers whose daily driving was monitored continuously for one year during 2003-04. On average, drivers spent 7 percent of their driving time talking or listening to a cell phone. A naturalistic study of drivers in Michigan conducted during 2009-10 also estimated that drivers talked on cell phones about 7 percent of the time, on average.
National observation surveys indicate the rate of drivers texting at any moment during the day is rising, especially among younger drivers. In 2015, 2.2 percent of all drivers and 4.9 percent of drivers estimated to be 16-24 years old were observed texting or otherwise manipulating hand held devices. That's a 267 percent increase from 0.6 percent in 2009 for all drivers and a 345 percent increase from 1.1 percent in 2009 for drivers 16-24 years old. In a 2015 national online survey, almost one-third of drivers reported sending a text message or e-mail while driving at least once in the past 30 days, and 42 percent said they had read a text or e-mail.
Who is most likely to use a cell phone while driving?
Younger drivers are more likely than older drivers to talk on phones and to text while driving.
In a 2015 national online survey, about 77 percent of drivers 19-24 years old and 78 percent of drivers 25-39 years old said they had talked on a cell phone while driving in the past 30 days, but only 60 percent of drivers 60-74 years old and 42 percent of drivers 75 and older said the same. A larger proportion of 19-24 and 25-39-year-old drivers also said they had read or sent a text or e-mail while driving in the past 30 days compared with drivers 60 and older.
A study that analyzed random samples of video recordings of daily driving by adults and newly licensed teenagers found no significant difference between the adult and teenage drivers in the percentage of cell phone conversations or dialing or reaching for phones.
There is evidence that people who use cell phones more frequently while driving may be riskier drivers in other respects. In an Institute study of drivers who were continuously monitored for one year, the drivers who spent the greatest amount of their driving time interacting with a cell phone also had the highest rates of near crashes and crashes. In an on-road study, drivers who reported frequent cell phone use drove faster, changed lanes more often and made more hard braking maneuvers than drivers who said they rarely used cell phones while driving.
How does talking on a cell phone or texting while driving affect crash risk?
There is growing evidence that talking on a cellphone increases crash risk, though it hasn't been firmly established.
Two separate epidemiological studies linked talking on a cell phone to a fourfold increase in the likelihood of a crash resulting in injury to the driver and in the risk of a crash involving property damage but no injury.
Two recent studies, including one from the Institute, suggest estimates from these early epidemiological studies may be too high. Based on data from over 3,000 drivers who were continuously monitored for up to 3 years during 2010-13, the Institute study found that the risk of a minor crash or crash severe enough to report to police doubled when drivers were talking on a cell phone compared with when they were not visibly distracted.
Similarly, the other study found that talking on a hand held cell phone doubled crash risk compared with when drivers were not distracted or judged to be driving impaired. However, another Institute study that took a detailed look at cell phone use during trips made by 105 drivers monitored for one year during 2003-04 found that talking on a cell phone did not significantly increase the risk of a near crash or crash compared with periods where drivers were not talking on the phone as much.
Texting or otherwise manipulating a cell phone while driving has consistently been linked to increased risk. The Institute's analysis of data from the 3,000 driver naturalistic study indicated that crash risk was 5 times greater when drivers were manipulating a cell phone compared with when they were not distracted.
Another study based on the same data found that texting alone was associated with a 6-fold increase in crash risk relative to when drivers were not distracted or judged to be driving impaired. In the Institute study that took a detailed look at the cell phone use of 105 drivers, reaching for, answering, or dialing a cell phone nearly tripled the risk of a near crash or crash compared with everything else drivers did while driving. Texting was not prevalent during the study period and was not observed.
How many crashes have been caused by drivers using cell phones or engaging in other distracting behaviors?
There are no reliable estimates of the number of crashes caused by distracted drivers. Based on national police reported data on fatal crashes in the United States during 2014, distraction was deemed a contributing factor in the crash for 3,000 of the 44,583 drivers involved in fatal crashes. 398 of these drivers were classified as distracted by cell phone use.
However, these statistics almost certainly underestimate the role of distraction in fatal crashes. Police crash reports aren't a reliable way to count cell phone related collisions because drivers often don't volunteer that they were on the phone and there is usually a lack of other evidence to determine drivers' phone use.
In an in depth study of a nationally representative sample of police reported crashes occurring during 2005-07 and involving at least one vehicle towed from the scene, drivers and witnesses were interviewed at the crash scene about driver inattention and other precrash behaviors. Based on these interviews, police reports and other information, a driver was conversing with a passenger in about 16 percent of the crashes.
In about 5 percent of the crashes, a driver was focusing on another occupant or object in the vehicle, and in about 3 percent, a driver was using a cell phone (talking, dialing, hanging up or text messaging). In about 2 percent of the crashes, a driver was eating or drinking.
The study didn't determine whether these behaviors contributed to the crash. It's likely that the estimates of distraction in this study also are imprecise, as they rely heavily on the accounts of drivers and observers.
How do cell phone use and texting affect driving performance?
The effect of cell phone use on driving performance has been extensively researched. Based on an Institute review of cell phone and driving research, nearly all experimental studies using driving simulators or instrumented vehicles reported that some measures of driver performance were affected by the cognitive distractions associated with cell phone tasks.
Statistical analyses that aggregated the results of 33 studies in one analysis and 23 studies in another reported significant delays in drivers' reaction time but little or no effect of cell phone conversations on lane keeping, speed or following distance.
An analysis aggregating the results of 28 experimental studies using driving simulators or instrumented vehicles reported that typing or reading text messages significantly slowed reaction time, increased lane deviations and increased the length of time drivers looked away from the roadway.
Cell phone use also affects how drivers scan and process information from the roadway. Drivers generally take their eyes off the roadway to dial or manipulate a hand held phone. In contrast, drivers engaged in cell phone conversations and other forms of cognitive distraction tend to concentrate their gaze toward the center of the roadway, but their attention still may be diverted from driving and this may make it difficult for drivers to process what they are looking at.
Using brain imaging techniques, researchers found a 37 percent reduction in brain activity associated with driving when subjects performed a task via a headset while steering a simulated vehicle. Other researchers have found similar suppression of brain activity associated with visual processing and attention when drivers are cognitively distracted. Consequently, cognitive distractions can lead to so called "inattention blindness" in which drivers fail to comprehend or process information from objects in the roadway even when they are looking at them.
How common are laws limiting drivers' use of cellphones?
Bans on hand held phone conversations while driving are widespread in other countries and are becoming more common in the U.S. In 2001, New York became the first state to ban hand held phone conversations by all drivers. Now, 14 states and the District of Columbia have similar laws.
In 2002, New Jersey became the first state to limit young drivers' use of any kind of cell phone. Now 37 states and the District of Columbia have similar restrictions. The District of Columbia in 2004 and Connecticut in 2005 prohibited texting while driving as part of a law broadly addressing driver distraction.
In January 2008, Washington became the first state to prohibit texting specifically by all drivers. Now texting is banned for all drivers in 46 states and the District of Columbia, and an additional two states (Missouri and Texas) prohibit texting only for novice drivers.
Do drivers comply with bans on hand held phone use and texting?
Institute research has documented that all driver bans on hand held phone conversations can have large and lasting effects on phone use. Based on observations of drivers conducted up to seven years after bans were implemented in New York, the District of Columbia and Connecticut, the rates of driver hand held cell phone conversations were an estimated 24-76 percent lower than would have been expected without a ban.
In a 2009 telephone survey, 56 percent of drivers in states with bans reported they use phones when driving, compared with 69 percent in states without such laws. The proportion of drivers who talked on phones and always talked hands free was 22 percent in states with all driver bans on hand held phones and 13 percent in states without all driver bans.
Phone bans seem to have less effect on younger drivers. Since Dec. 1, 2006, North Carolina has banned the use of any telecommunications device by drivers younger than 18. Eleven percent of teenagers leaving high schools in the afternoon were using phones prior to the ban, and this did not change significantly when measured two years after the restriction took effect.
There is scant information on drivers' compliance with texting bans. The Institute's 2009 survey of drivers found that among 18-24 year-olds, 45 percent reported texting while driving in states that bar the practice, just shy of the 48 percent of drivers who reported texting in states without bans. Among drivers ages 25-29, 40 percent reported texting in states with bans, compared with 55 percent in states without bans.
The National Highway Traffic Safety Administration has conducted high visibility enforcement campaigns in Hartford, Conn., Syracuse, N.Y., the Sacramento Valley Region in California, and in the state of Delaware as a way to increase compliance with cell phone and texting bans.
After programs of publicized, high intensity enforcement of hand held cell phone and texting bans were implemented, the number of drivers observed holding a phone to their ear declined by 57 percent in Hartford, 32 percent in Syracuse, 34 percent in the Sacramento Valley region and 33 percent in Delaware.
Significant declines also were observed in 3 of the 4 groups of comparison communities where high visibility enforcement campaigns were not conducted. Observed manipulation of hand held phones (e.g., dialing, texting) decreased significantly in Syracuse, N.Y., and Hartford, Conn., following the enforcement initiative and did not decrease in the comparison communities.
Do bans on hand held phone use and texting reduce crashes?
It is not clear whether banning hand held phone use or texting reduces crashes. A 2009 analysis by the Highway Loss Data Institute (HLDI) found that hand held bans had no effect on insurance collision claim rates.
Researchers compared rates of claims for crash damage in three states and the District of Columbia before and after hand held phone use bans went into effect. They found no significant change in claim rates for two jurisdictions relative to comparison states and small, but significant, increases in claim rates in the other two.
A 2010 HLDI study examined rates of insurance collision claims before and after driver texting bans were enacted in four states. There was no significant change in one state relative to comparison states and significant increases of 7-9 percent in three states. Increases in claim rates also were found for drivers 25 and younger in these three states.
The Institute reviewed 11 studies of the effects of all driver hand held phone bans and texting bans on crashes including the two HLDI studies. The results were mixed, so it is not clear if laws limiting drivers' cell phone use are having beneficial effects on crashes.
Bans may not have a beneficial effect on crashes even with strong enforcement. Four waves of enforcement campaigns aimed at reducing hand held cell phone use were conducted in Hartford, Conn. and Syracuse, N.Y. during 2010-11. The campaigns reduced observed rates of cell phone conversation and manipulating. However, an analysis comparing insurance collision claims in counties with the campaigns to comparison counties without them did not find a corresponding reduction in crashes reported to insurers.
Can technology be used to reduce crash risks related to distracted driving?
Crash avoidance technology may be the most promising avenue for reducing crash risks related to distractions of any type. Field studies of several prototype collision warning systems suggest these systems may not reduce the prevalence of distracted driving; however, these technologies can help prevent or mitigate crashes.
Warnings can redirect a distracted, inattentive or sleepy driver's attention back to the roadway if it detects the potential for a collision. Some systems attempt to avoid the collision altogether if a driver does not respond fast enough or does not respond at all.
Automakers are integrating "infotainment" systems into vehicles to let drivers and other occupants plug in or wirelessly connect portable electronic devices such as cell phones to vehicle entertainment and communication systems. Many newer infotainment systems and portable devices can be controlled using voice commands.
Several experimental studies have shown that drivers take shorter glances away from the roadway and keep their eyes on the road for a greater proportion of the time when interacting with a portable device using voice commands than when using their hands.
However, voice systems are not all designed the same, and the benefits can vary. An Institute study found that drivers were able to place calls and enter addresses into a navigation system during highway driving more quickly and keep their eyes on the roadway longer when using a system in which a single detailed voice command was used to complete the tasks compared with a system in which multiple voice commands were used to navigate different menus.
On the flip side, drivers experience many more errors when entering an address using a single voice command than when entering it using voice commands. The effects of voice recognition technology on crash risk are unknown. NHTSA has issued voluntary guidelines for integrated infotainment systems in an effort to minimize the visual and manual
distraction potential of these systems.
Phone applications that restrict or limit access to electronic devices also have been developed. These apps generally work when vehicles are in motion and can silence the phone, redirect incoming calls to voicemail or respond to text messages with a preprogrammed message.
A study examining phone use during work related driving found that when phone use was restricted by a blocking application, employees answered fewer calls with their employer provided phones while the vehicle was moving and made more calls when the vehicle was stopped.
Another study examining smartphone use among 182 novice teens over one year found that teens who had an app on their smartphone that restricted cell phone use and blocked incoming calls and messages made significantly fewer calls and texts per mile driven compared with teens who did not have the app. At this point, it is unclear to what extent these apps are used and to what extent they affect crash risk.
