MAY 2011 STATISTICAL ANALYSIS OF CELL PHONES, TEXTING, DRIVING AND RELATED CRASHES

1. How many people use cellphones?

Cell phone use in the United States has grown quickly during the past decade. There were about 293 million wireless cell phone subscribers as of June 2010 according to CTIA,The Wireless Association, an industry trade group. That's up 51 percent from 194 million in June 2005 and 3 times the 97 million wireless subscribers in June 2000. Minutes of use have surged to about 2.3 trillion in June 2010 from 195 billion in June 2000.

2. Do drivers frequently use phones behind the wheel?

Yes, though it's hard to determine accurately just how many drivers use phones. Combining observational and self reported data on phone use the federal government estimated that drivers using phones nearly tripled during 2000-08, from 4 to 11 percent, and then declined to 9 percent in 2009. Federal observational data indicate that 5 percent of drivers in 2009 were talking on hand held phones at any moment during the day. This means about 672,000 passenger vehicles on the road at any moment during the day were driven by people talking on hand held phones.

A 2009 Institute telephone survey of 1,219 drivers 18 and older indicates phone use may be somewhat lower than government estimates. Drivers on average reported spending about an hour in the car each day with about 4 minutes of that time on the phone. This translates into roughly 7 percent of time behind the wheel on the phone. The discrepancy between the two estimates may be a result of drivers in the Institute survey understating how much phoning while driving they do because the practice has negative connotations. It also could reflect different methodologies. Government researchers observed hand held phone use among drivers waiting at intersections during the daytime then adjusted this for self reported hands free use. The Institute's survey estimates self reported driver phone use on all kinds of roads during all hours.

3. Who is most likely to talk on a cell phone while driving?

Young drivers ages 16-24 are more likely than other drivers to talk on hand held cellphones according to daytime observational surveys of drivers the federal government conducted nationwide in 2009. Eight percent of drivers ages 16-24 were observed talking on hand held phones compared with 5 percent of those ages 25-69 and 1 percent of drivers 70 and older. In the Institute's 2009 survey of drivers' self reported phone use people younger than 30 spent 16 percent of driving time on the phone compared with 7 percent for drivers 30-59 years old, and just 2.5 percent for drivers 60 and older.

Men in the Institute's survey reported spending slightly more time on the phone than women (7 percent versus 6 percent). This differs from the government's and other observations that female drivers use cellphones more. Drivers reported using phones more on weekdays and during afternoons and evenings. Use rates were 8 percent during these times. This is in line with government observations that use is higher on weekdays.

4. Does using a cell phone while driving increase crash risk?

Yes. Two controlled studies link talking on a cell phone directly to increased crash risk. A 2005 Institute study of drivers in Western Australia found cell phone users four times as likely to get into crashes serious enough to injure themselves. The study used cell phone billing records to verify phone use of crash involved drivers. Increased risk was similar for males and females, drivers younger than 30 and those 30 and older, and hands free and hand held phones. The findings were consistent with 1997 research that showed phone use among Canadian drivers was associated with a fourfold increase in the risk of a property damage crash. The Canadian study also used cell phone billing records to verify phone use of drivers.

5. How many crashes have been caused by drivers using cellphones?

The federal government estimates that in 2009, 5,474 people were killed and an additional 448,000 were injured in motor vehicle crashes that were reported by police to have involved distracted driving. The government estimates that 18 percent of these deaths and 5 percent of these injuries involved cellphones. However, these estimates are imprecise and likely under estimate distraction's role in crashes as many police reports don't have information on distracting events. 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.

It is possible to estimate the expected number of crashes linked to phoning while driving. An Institute analysis suggests this practice could account for 22 percent of all crashes, or about 1.3 million in 2008 based on how much phoning while driving motorists admitted to researchers and the estimated risk of driver phone use. |However, there is a disconnect between estimated crashes and real world data which indicate that crashes have been holding steady in recent years even as cell phone use in general and driver use of phones in particular have proliferated.

About 5.5 million police reported motor vehicle crashes occurred during 2009, the latest year for which federal data are available. This count doesn't differ much from the approximately 6 million crashes recorded annually during the early 1990s when cellphones started getting popular, and it is lower than the 6.4 million crashes in 2000 when federal researchers began documenting the increase in phone use while driving.

An increase in cell phone related crashes isn't showing up in insurance claims either. An analysis by the Highway Loss Data Institute indicates that the frequency of insurance claims for crash damage filed under collision coverage during 1998-2008 hasn't increased even though driver phone use has escalated.

A 2006 Virginia Tech Transportation Institute study used video cameras to monitor drivers in about 100 vehicles for about a year. Four percent of crashes or near crashes were attributable to talking on a cell phone researchers estimated.

6. Are hands free cellphones safer?

No, at least not after the conversation begins. Two studies of crashes using cell phone billing records to verify phone use found about a fourfold increase in crash risk with conversing on both hands free and hand held phones. The studies were unable to estimate crash risk from different types of hands free devices. They also were unable to determine whether there was any benefit associated with hands free devices while placing the call. Experimental research using driving simulators indicates that phone conversation tasks, whether using hand held or hands free devices, affect some measures of driving performance. Hands free phones may eliminate some of the physical distraction of handling phones, but the cognitive distraction from phone conversations remains.

7. How does cell phone use affect driving performance?

An Institute review of more than 120 cell phone studies, about half of which were experimental studies using driving simulators or vehicles instrumented with video cameras, sensors, and other equipment, found that nearly all reported that some measures of driver performance were affected by the cognitive distractions associated with cell phone tasks. Phone conversation tasks typically increased reaction times and travel speeds and increased lane deviations and steering wheel movements. Statistical analyses that aggregated the results of 33 studies and 23 studies, respectively, reported similar findings. Some studies have found that older drivers' performance is more affected by cell phone tasks particularly their reaction time. Few studies included drivers younger than 18, and evidence is mixed on the effects of phone use for teenage drivers compared with adult drivers. Findings also are mixed on whether driving performance while talking on a cell phone improves with practice. Some simulator studies suggest that the negative impact of phone use on driving performance may lessen with experience. Other simulator research has found no change in performance with practice.

Using functional magnetic resonance imaging researchers at Carnegie Mellon University found a 37 percent reduction in brain activity associated with driving when research subjects listened via a headset to spoken sentences that they judged as true or false while steering in a driving simulator. Researchers concluded that listening and processing information from a phone conversation can draw mental resources away from driving worsening driving performance even when drivers are not holding or dialing a phone.

Further evidence comes from a few studies of small samples of people observed during their everyday driving. One study included drivers of 100 vehicles instrumented with video cameras and other monitoring technologies. Only a few serious crashes occurred, but researchers calculated the odds of being in a near crash or crash were 2.8 times higher when dialing a hand held phone than when phones weren't being used. The odds of a near crash or crash were 1.3 times higher when talking on a hand held phone although this was not statistically significant. But because drivers spend more time talking on a hand held phone than dialing the percentage of crashes and near crashes estimated to be attributable to talking and dialing on hand held phones were both about 4 percent.

8. Do bans on hand held phones work to reduce driver phone use?

Institute research has documented that all driver bans on hand held phoning can have large and lasting effects on phone use. In November 2001 New York became the first state to implement a universal ban on hand held cellphones. Observed driver hand held cell phone use declined by an estimated 47 percent immediately after the ban. Use then began going back up, but when measured more than 7 years after the ban use was 24 percent lower than would have been expected without the ban. Soon after a ban was passed in the District of Columbia in 2004 observed driver hand held phone use dropped by 41 percent. Nearly five years after the ban the rate of phone use was 43 percent lower than would have been expected without a ban. Connecticut's ban took effect in 2005. Observed hand held phone use declined an estimated 76 percent immediately after a ban; more than 3 years later use was 65 percent lower than would be expected without a ban.

In the Institute's telephone survey of cell phone use drivers in states with hand held bans were less likely to say they talk on phones while driving. Forty-four percent of drivers in states with bans reported they don't use phones when driving compared with 30 percent in states without such laws. The percent of drivers who talk on phones and always talk hands free was 22 in states with all driver bans on hand held phones, and 13 in states without all driver bans.

9. Do hand held phone bans reduce crashes?

There is no evidence so far that banning hand held phone use reduces crashes even though Institute research demonstrates that bans on hand held phoning while driving can have big and long term effects in curbing phone use. A 2009 analysis by the Highway Loss Data Institute found that hand held bans had no effect on insurance claims. Researchers compared claims for crash damage in 4 jurisdictions before and after hand held phone use bans finding steady claim rates before and after laws went into effect.

Many drivers still use hand held phones where use is banned, and others may simply switch to hands free phones. Given that crash risk increases substantially with drivers' use of either hand held or hands free phones, bans on hand held cell phones won't eliminate the problem entirely. Laws prohibiting hands free phones are difficult to enforce plus drivers may be unfamiliar with restrictions in their state. In the Institute telephone survey 18 percent of drivers in states with a universal ban on hand held phone use either believed there was no law or were unsure. The proportion was even higher (48 percent) among drivers in states with a universal texting ban. Many drivers don't believe police pay much attention to them. Only 29 percent of drivers in states with universal hand held phone bans who knew about the bans and 22 percent of drivers in states with universal texting bans who were aware of the restrictions felt they were strongly enforced.

10. How common are bans on hand held cellphones and texting?

Bans are widespread in other countries and are becoming more common in the U.S. Nine states (California, Connecticut, Delaware, Maryland, New Jersey, New York, Oregon, Utah, and Washington) and the District of Columbia have enacted laws that ban drivers of all ages from using hand held cellphones.

More common in the US are laws that restrict young drivers from using any type of cell phone. Teenage drivers in 29 states and the District of Columbia have such laws. School bus drivers in 19 states and the District of Columbia are restricted from using all cellphones while driving a bus.

In Australia, drivers in Victoria and Tasmania are banned from using all phones except ones secured in a commercially designed holder fixed to the vehicle that can be operated without touching any part of the phone.

Text messaging is banned for all drivers in 30 states and the District of Columbia. In addition, novice drivers are banned from texting in 9 states (Alabama, Indiana, Maine, Mississippi, Missouri, New Mexico, Oklahoma, Texas, and West Virginia), and school bus drivers are banned from text messaging in 3 states (Mississippi, Oklahoma, and Texas).

11. Why do more laws cover only teenage drivers?

Cell phone bans for young drivers are becoming more common amid concerns about the role distractions play in teenagers' elevated crash risk. Distractions of any type are a common factor in crashes of newly licensed 16 year old drivers. Some research also shows teenage drivers tend to use cellphones and other emerging technologies more than adult drivers. States increasingly have graduated licensing laws that place restrictions on newly licensed drivers, e.g., limiting night time driving and the number of passengers a novice driver can carry. Cell phone bans are being added to those restrictions.

12. Do teenagers comply with cell phone bans?

Young drivers often ignore cellphone restrictions according to an Institute study of North Carolina's cell phone ban for young beginning drivers. The state bans the use of any telecommunications device by drivers younger than 18 under its graduated licensing system. Observed cell phone use by teenagers leaving high schools in the afternoon changed little from 1-2 months before to 5 months after the restriction took effect on Dec. 1, 2006. About 11 percent of teenage drivers were seen using phones before the law. That percentage rose slightly to 12 percent in the post law survey. Cell phone use remained steady at about 13 percent at comparison sites in South Carolina which doesn't restrict teenage drivers' phone use. When observed post law, less than 1 percent of teenage drivers in North Carolina were using hands free phones. About 2 percent were observed dialing or texting and about 9 percent were holding a phone to their ear.

The study coupled driver observations with telephone surveys of North Carolina parents and their teenagers. In post law surveys, about two-thirds of teenagers said they knew about their state's law compared with 39 percent of parents. Three-quarters of teenagers and 95 percent of parents said they approved of the law. The proportion of teenagers who reported using phones while driving declined somewhat following the law. However, of those who owned a phone and admitted to ever talking on the phone while driving, about half admitted they used their phones, if they had driven, on the day prior to the interview. There was no evidence of focused enforcement or publicity of the law. Only 22 percent of teenagers and 13 percent of parents believed the ban was being enforced fairly often or a lot.

13. Is cell phone use more distracting to drivers than other tasks?

Evidence is mixed. For example, some experimental studies found that phone conversations are more disruptive than conversations with passengers or adjusting a radio. However, two statistical analyses combining the results of multiple experimental studies found similar decrements in reaction time for conversation tasks with passengers and with hand held or hands free phones. Two studies reported that talking on cellphones or having a 0.08 percent blood alcohol concentration (BAC) — the legal threshold for impairment — has a comparable effect on some simulated driving tasks. However, the risks associated with alcohol impairment accumulate over the entire duration of a trip whereas the risks of cell phone use generally apply for only a portion of a trip. In addition, crash risk increases substantially at very high BACs, and the implications of the experimental studies for drivers in their own vehicles is unknown.

14. Is texting while driving a problem?

Texting in general is on the increase. Annualized text messages soared to about 1.8 trillion in June 2010 from 57 billion in June 2005. Many people report that they text while driving. A 2009 Institute survey found that 13 percent of drivers of all ages have texted while driving, and this jumps to 43 percent among 18-24 year old drivers. Similar results were found in other studies.

There hasn't been a lot of research on the safety effects of texting and driving, but three studies of young drivers using driving simulators all found that receiving, and especially sending text messages impeded drivers' reaction times and lane keeping ability. In a study involving large trucks instrumented with video cameras and other monitoring technology the odds of a traffic conflict, lane drift, near crash, or crash were 23 times higher when a truck driver was texting. A limitation is that less than 1 percent of the incidents involved crashes; most were lane drifts or other driver errors. It's unknown how such incidents relate to actual crashes. It also is unclear whether the results generalize to passenger vehicle drivers.

15. Do drivers comply with text messaging bans?

So far it appears that drivers, especially young adults, largely shrug off texting bans. An Institute study found that among 18-24 year-olds — the group most likely to text — 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 25-29, 40 percent reported texting in states with bans compared with 55 percent in states without bans.

Many drivers are unclear about the laws in their state. Forty-eight percent of drivers in states with universal texting bans believed there was no law or were unsure. Plus, only 22 percent of drivers who were aware of the restrictions felt they were strongly enforced.

16. Do bans on driver text messaging reduce crashes?

Not according to research by the Highway Loss Data Institute. A 2010 study examined insurance claims filed for damage to vehicles before and after driver texting bans were enacted in four states. There was no reduction in claim rates relative to comparison states. Rather, there was a significant increase of 7-9 percent in the frequency of claims in 3 of the 4 study states. Increases in the frequency of claims also were found for rated drivers 25 and younger in these 3 states.

17. Can technology be used to prevent crashes caused by distracted driving?

Automakers are rolling out crash avoidance systems that warn drivers when they are not paying attention. Some systems may intervene if the system judges that a crash is imminent. Systems like lane departure warning and forward collision warning promise to prevent many kinds of distracted driving crashes, not just those that result from cell phone use. But this isn't a quick fix. Most new vehicles don't have crash avoidance features, and it will take some time before the systems are in wide use as newer vehicles supplant older ones. Plus, the effects of these technologies on real world crashes have not yet been established.