Mobile phones and driving safety

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This Manhattan driver is juggling two phones at once

Mobile phone use while driving is common but controversial. Using a cellular telephone while operating a motor vehicle has been shown to increase the risk of accident. Because of this, many governments have made the use of a cell phone while driving illegal.

1 Increased risk
2 Legislation
- 2.1 Effectiveness of legislation
- 2.2 List of countries with bans
3 References
4 External links

[edit] Increased risk

The American National Highway Traffic Safety Administration (NHTSA) says that the inattention and distraction created by the use of a cellular telephone while driving is similar to that associated with other distractions in increasing crash risk. However, the data are insufficient to indicate the magnitude of the safety problem.^[1]

[edit] Case-crossover studies

A 1997 American study ^[2] and a 2005 Australian study ^[3] both estimated the risk of a collision when using a cellular telephone was four times higher than the risk when a cellular telephone was not being used. 699 and 456 drivers, respectively, who owned phones, were involved in crashes, and volunteered for the studies were examined. By collecting volunteers' cell phone records, scientists were able to determine who placed telephone calls shortly before the time of crash, and through case-crossover analysis (a technique often used in medical studies of heart-attacks and air pollution) of cell phone habits, calculated the increase in risk. Both studies found that hands-free devices were not considerably safer.

[edit] Epidemiological cohort studies

A more traditional study method was used by the Société de l'assurance automobile du Québec (SAAQ) for their 2003 study. Questionnaires were sent to 175,000 drivers and analysis was done on the 36,078 who responded. The questionnaire asked about driving habits, risk exposure, collisions over the past 24 months, socio-demographic information, and cell phone use. Questionnaires were supported with data from cell phone companies and police crash records. The study found that the overall relative risk (RR) of having an accident for cell phone users when compared to non-cell phone users averaged 1.38 across all groups. When adjusted for kilometers driven per year and other crash risk exposures, RR was 1.11 for men and 1.21 for women. They also found that increased cell phone use correlated with an increase in RR. When the same data were reanalyzed using a Bayesian approach, the calculated RR of 0.78 for those making less than 1 call/day and 2.27 for those with more than 7 calls/day was similar to cohort analysis. When the data were reanalyzed using case-crossover analysis, RR was calculated at a much higher 5.13. The authors expressed concern that misclassification of phone calls due to reporting errors of the exact time of the collisions was a major source of bias with all case-crossover analysis of this issue. ^[4]^[5]^[6]

[edit] Simulation studies

*Means and standard errors (in parentheses) for the Alcohol, Base line, and Cell-Phone conditions*
	Alcohol	Base line	Cell Phone
Total Accidents	0	0	3
Brake Onset Time (msec)	888 (51)	943 (58)	1022 (61)
Braking Force (% of maximum)	69.6 (3.6)	56.4 (2.5)	55.2 (2.9)
Speed (MPH)	52.8 (.08)	54.9 (.08)	53.2 (.07)
Following Distance (meters)	26.5 (1.7)	27.3 (1.3)	28.5 (1.6)
½ Recovery Time	5.4 (0.3)	5.4 (0.3)	6.2 (0.4)

Simulations are particularly useful for comparing cell phone use while driving with the known-dangerous drunk driving. A 2003 study by University of Utah Psychology professor David Strayer measured response time, following distance, and driving speed of a control group, subjects at the legal BAC limit of 0.08%, and subjects involved in cell phone conversations. Data from the report are listed to the right.

From the report:

Drivers in the cell-phone condition exhibited a sluggish behavior (i.e., slower reactions) which they attempted to compensate for by increasing their following distance. Drivers in the alcohol condition exhibited a more aggressive driving style, in which they followed closer, necessitating braking with greater force.

After controlling for driving difficulty and time on task, the study concluded that cell phone drivers exhibited greater impairment than intoxicated drivers. ^[7]

[edit] Meta-analysis

A 2005 review by the Hawaiian legislature entitled "Cell Phone Use and Motor Vehicle Collisions: A Review of the Studies"^[8] contains an analysis of the current state of knowledge on cell phone/motor vehicle accident causality.

Meta-analysis by The Canadian Automobile Association^[9] and The University of Illinois^[10] found that response time while using both hands-free and hand-held phones was approximately 0.5 standard deviations higher than normal driving (i.e., an average driver, while talking on a cell phone, has response times of a driver in roughly the 40th percentile).

[edit] As a percentage of distraction-related accidents

Driver inattention is estimated to be a factor in between 20 to 50 percent of all police-reported crashes. Driver distraction, a sub-category of inattention, has been estimated to be a contributing factor in 8 to 13 percent of all crashes. Of distraction-related accidents, cell phone use may range from 1.5 to 5 percent of contributing factors.^[11] However, large percentages of unknowns in each of those categories may cause inaccuracies in these estimations. A 2001 study sponsored by The American Automobile Association recorded "Unknown Driver Attention Status" for 41.5 percent of crashes, and "Unknown Distraction" in 8.6 percent of all distraction related accidents.^[12] According to NHTSA, "There is clearly inadequate reporting of crashes that may be related to cellular telephone use while driving".^[1]

Currently, "Outside person, object, event" (rubbernecking) is the most reported cause of distraction-related accidents, followed by "Adjusting radio/cassette/CD". "Using/dialing cell phone" is eighth.

[edit] Hands-free

Hands-free car kit

Driving while using a hands-free device is not safer than while using a hand held cell phone, as concluded by case-crossover studies.^[2]^[3] epidemiological,^[4]^[5] simulation,^[7] and meta-analysis^[9]^[10]. The increased "cognitive workload" involved in holding a conversation, not the use of hands, causes the increased risk.^[13]^[14]^[15] One notable exception to that conclusion is a study by headset manufacturer Plantronics, which found 71 percent of the test subjects steered more accurately, 100 percent had faster brake reaction times, and 92 percent maintained a more consistent speed when using a headset versus handheld.^[16] The consistency of increased crash risk between hands-free and hand held cell phone use is at odds with legislation in many locations that prohibits hand held cell phone use but allows hands-free. Dialing a cell phone is more distracting than talking on a cell phone, ^[17] and hands-free devices that offer voice-dialing may reduce or eliminate that increased risk.

[edit] As compared to conversation with a passenger

The scientific literature is mixed on the dangers of talking on a cell phone versus those of talking with a passenger. The common conception is that passengers are able to better regulate conversation based on the perceived level of danger, therefore the risk is negligible. A study by a University of South Carolina psychology researcher featured in the journal, Experimental Psychology, found that planning to speak and speaking put far more demands on the brain’s resources than listening. Measurement of attention levels showed that subjects were four times more distracted while preparing to speak or speaking than when they were listening.^[18] The Accident Research Unit at the University of Nottingham found that the number of utterances was usually higher for mobile calls when compared to blindfolded and non-blindfolded passengers across various driving conditions. The number of questions asked averaged slightly higher for mobile phone conversations, although results were not constant across road types and largely influenced by a large number of questions on the urban roads.^[19] A 2004 University of Utah simulation study that compared passenger and cell-phone conversations concluded that the driver performs better when conversing with a passenger because the traffic and driving task become part of the conversation. Drivers holding conversations on cell phones were four times more likely to miss the highway exit than those with passengers, and drivers conversing with passengers showed no statistically significant difference from lone drivers in the simulator.^[20] A study led by Andrew Parkes at the Transport Research Laboratory, also with a driving simulator, concluded that hands-free phone conversations impair driving performance more than other common in-vehicle distractions such as passenger conversations.^[21]

In contrast, the University of Illinois meta-analysis concluded that passenger conversations were just as costly to driving performance as cell phone ones.^[10] AAA ranks passengers as the third most reported cause of distraction-related accidents at 11 percent, compared to 1.5 percent for cellular telephones.^[12] A simulation study funded by the American Transportation Research Board concluded that driving events that require urgent responses may be influenced by in-vehicle conversations, and that there is little practical evidence that passengers adjusted their conversations to changes in the traffic. It concluded that drivers' training should address the hazards of both mobile phone and passenger conversations.^[22]

[edit] Texting

The scientific literature on the dangers of driving while sending a text message from a mobile phone, or driving while texting, is limited. A simulation study at the Monash University Accident Research Center provided strong evidence that retrieving and, in particular, sending text messaged has a detrimental effect on a number of safety critical driving measures. Specifically, negative effects were seen in detecting and responding correctly to road signs, detecting hazards, time spend with eyes off the road, and (only for sending text messages) lateral position. Surprisingly, mean speed, speed variability, lateral position when receiving text messages, and following distance showed no difference. ^[23] A separate, yet unreleased simulation study at the University of Utah found a sixfold increase in distraction-related accidents when texting.^[24]

The lack of scientific studies may be indicative of a general assumption that if talking on a mobile phone increases risk, then texting also increases risk, and probably more so. 89% of U.S. adults think that text messaging while driving is "distracting, dangerous and should be outlawed."^[25] This has been supported by legislatures, and most countries and states that ban hand-held cell phones while driving also ban texting while driving.

[edit] Driving speed

In a study published in January 2008, Professor David Strayer at the University of Utah reported that motorists who talk on mobile phones drive slower, pass sluggish vehicles less often and take longer to complete their trips. ^[26]

[edit] Legislation

Accidents involving a driver being distracted by talking on a mobile phone have begun to be prosecuted as negligence similar to driving while intoxicated. In the United Kingdom, from 27 February 2007, motorists who are caught using a hand-held mobile phone while driving will have three penalty points added to their license in addition to the fine of £60.^[27] This increase was introduced to try to stem the increase in drivers ignoring the law.^[28] Israel, Japan, Portugal and Singapore prohibit all mobile phone use while driving, including hands-free. [1]

[edit] Effectiveness of legislation

Current laws banning cell phone use in New York and Connecticut have proven to be ineffective, due to a lack of visible enforcement. The percentage of offenders decreased from 2.3% to 1.1% immediately after the ban was implemented, but after being in effect for a year the percentage increased to 2.1%, which is not significantly different from the pre-ban figure. The authors of the study conclude that "vigorous enforcement campaigns accompanied by publicity appear necessary to achieve longer term compliance."^[29]