Distracted Driving

Overview

 Distracted driving is common, though difficult to measure and sometimes observe. Similar to drowsy driving, distracted driving is associated with lifestyle patterns, attitudes, and choices (Ranney, 2008). Distracted driving has received a great deal of attention over the last decade. The U.S. Department of Transportation held two distracted driving summits in Washington, DC, and developed a Blueprint for Ending Distracted Driving (NHTSA, 2012). Although much of the attention and research has concentrated on cell phones and texting, that is just one of many potential distractions behind the wheel. NHTSA has defined distracted driving as “anything that diverts the driver’s attention from the primary tasks of navigating the vehicle and responding to critical events. To put it another way, a distraction is anything that takes your eyes off the road (visual distraction), your mind off the task of driving (cognitive distraction), or your hands off the wheel (manual distraction)” (NHTSA, n.d.). NHTSA hosted a technical meeting in 2015 to discuss cognitive distraction or mind-wandering (when drivers take their minds off the driving task).

A related issue that is emerging as a growing safety concern is distracted pedestrians using cell phones and electronic devices in the roadway environment. A literature review from NHTSA found that, based on the limited amount of research done on pedestrian distraction, distraction is associated with a small but statistically significant decrease in pedestrian safety (Scopatz & Zhou, 2016). This issue is discussed in more detail in the Pedestrian Safety chapter.

Problem size and characteristics. Distraction occurs when a driver’s attention is diverted away from driving to some other activity. A distraction can be produced by something a driver sees or hears, some physical task not directly involved in driving such as eating or operating the car radio, or mental activities such as cell phone conversations (Goodwin et al., 2005, Section III).

It is clear that the public perceives driver distraction to be a serious traffic safety issue. In 2013 the AAA Foundation for Traffic Safety surveyed 3,103 U.S. residents and found that about 9 in 10 (88%) of people  say distracted driving is a “somewhat” or “much bigger” problem today compared to 3 years ago, and 89% believe drivers talking on cell phones are a “somewhat” or “very serious” threat to their personal safety (Hamilton et al., 2013). In 2015 the AAA Foundation repeated this survey with 2,442 U.S. residents and found that almost the same proportion (85%) say distracted driving is a “somewhat” or “much bigger” problem today compared to 3 years ago, and 86% believe drivers talking on cell phones are a “somewhat” or “very serious” threat to their personal safety (AAAFTS, 2016). This trend continued in the 2017 AAA Foundation survey conducted with 2,613 respondents (AAAFTS, 2018). Distracted driving was reported to be the most prevalent traffic safety problem by the majority (87.5%) of respondents. Almost all respondents (97%) reported that drivers who text or email while driving pose a serious threat, followed by drivers who talk on the phone while driving (88%). Similarly, in 2012 NHTSA conducted 6,016 telephone interviews and asked respondents how safe they would feel in a variety of situations in which they are passengers in vehicles operated by drivers who are engaged in other activities while driving. NHTSA found that about two-thirds (66%) would feel “somewhat” or “very” unsafe if the driver was to “talk on a cell phone while holding the phone” and almost all (95%) would feel “somewhat” or “very” unsafe if the driver was to “read emails or text messages” or “send text messages or emails” (Schroeder et al., 2013). This survey was repeated in 2015 with 6,011 respondents and very similar proportions were reported for these questions (Schroeder et al., 2018).

Although people are concerned about distracted driving they frequently admit to engaging in such behaviors behind the wheel. In the 2013 AAA Foundation survey two-thirds (67%) of respondents admitted to talking on the phone while driving during the past 30 days (Hamilton et al., 2013). A third (35%) admitted to reading text messages while driving and a fourth (26%) had sent text messages. The 2015 AAA Foundation survey found that more than two-thirds (69.9%) of respondents admitted to talking on the phone while driving during the past 30 days (AAAFTS, 2016). Two in five drivers (42.3%) admitted to reading text messages while driving in the past 30 days, and nearly one-third (31.5%) had sent text messages. The proportions continued to increase in the 2017 AAA Foundation survey in which 45% of drivers reported reading and 35% reported composing messages and emails while driving (AAAFTS, 2018). These findings show that the problem has gradually worsened since the 2013 survey. The AAA Foundation summarized its findings by observing that a substantial number of drivers have a “Do as I say, not as I do” attitude with regard to distracted driving – they view these behaviors as dangerous, but engage in them nevertheless. The 2015 NHTSA survey also asked about a variety of behaviors related to distracted driving (Schroeder et al., 2018). Among the behaviors that drivers reported doing at least sometimes:

• 82% talking to other passengers;
• 68% adjusting the car radio;
• 48% eating or drinking;
• 42% interacting with children in the back seat;
• 38% making or accepting phone calls;
• 36% using a navigational system;
• 36% using a smartphone for driving directions;
• 17% changing CDs, DVDs, or tapes;
• 12% reading email or text messages;
• 9% sending text messages or email;
• 5% taking pictures with phones.

The type of device and interaction also influences drivers’ perception of the potential for distraction and their willingness to use the device while driving. People perceive the use of hands-free devices as less risky than the use of handheld devices when driving. The proportion of drivers who reported talking on hands-free cell phones (60.5%) in the 2017 AAA Foundation (2018) survey was higher than those who reported talking on handheld cell phones (49.1%). Similarly, nearly half (47%) of the respondents in the 2015 NHTSA telephone survey reported feeling safe if the driver was using a hands-free cell phone to make or answer calls; this is a 7-point and 27-point increase from the reported results of the NHTSA surveys conducted in 2012 and 2010 respectively (Schroeder et al., 2013; Schroeder et al., 2018; Tison et al., 2011).

Many factors can affect drivers’ decisions to engage in distracted driving. Most often, the perceived benefits outweigh the perceived risks (Lissy et al., 2000). Recent research has focused on factors influencing teen drivers’ cell phone use. Trivedi et al. (2017) conducted a longitudinal multistage survey study of teens starting in 10th grade through 2 years after high school. They found that peer texting behaviors were significantly associated with participants’ own reported texting behaviors while driving. A recent study of 249 university undergraduate students (18-44 years, M = 22) reported that the perceived benefits of cell phone conversations while driving include less boredom and the feeling of “getting more done” (Sanbonmatsu et al., 2016). Students who reported using their cell phones while driving were also more likely to perceive higher ability to drive when distracted for themselves and others. Unsurprisingly, these students were also less likely to support legislation to restrict cell phone use while driving. The presence of legislation regulating cell phone use does not necessarily prevent drivers from engaging in such behaviors. An analysis of reported cell phone use among U.S. adolescent drivers (16 to 18 years old) was conducted using the 2011-2014 Traffic Safety Culture surveys. The study found that legislation banning handheld phone use may lower the incidence of reported phone conversations in this population; however, texting bans were not associated with similar decreases in reported texting behaviors while driving (Rudisill et al., 2018).

The role of distraction in crashes can be difficult to determine because pre-crash distractions often leave no evidence for LEOs or crash investigators to observe and drivers are often reluctant to admit to having been distracted right before a crash. Distraction-affected crashes is a relatively new measure that focuses on distractions that are most likely to influence crash involvement, such as dialing a cell phone or texting, and distraction by an outside person/event (NHTSA, 2012). According to the NCSA (2020), there were 2,841 fatalities in distraction-affected crashes in 2018. This represents a decrease of 12% from the 3,242 fatalities in 2017 (NCSA, 2019, 2020). Eight percent (2,628) of all fatal crashes in 2018 were distraction-affected crashes (NCSA, 2020).

The risks posed by specific distracted driving behaviors are beginning to be understood thanks to naturalistic driving studies that use onboard sensors and cameras to capture data right before crashes as well as during normal driving situations. The Second Strategic Highway Research Program Naturalistic Driving Study (SHRP2 NDS) included 3,500 participants, 35 million miles of continuous driving data, and 905 injury and property-damage-only (PDO) crashes. As such, it provided the first opportunity to perform a direct case-cohort analysis of the crash risk associated with  observable distractions compared to regular driving (Dingus et al., 2016). In the table below, a change in risk greater than 1 represents increases in crash risk due to the secondary task, while a change in risk less than 1 represents a decrease in crash risk. For example, interacting with a handheld cell phone increases the risk of a crash 3.6 times compared to baseline driving without a phone in hand. The table also shows baseline prevalence of the distraction in terms of the percentage of time drivers engaged in a distracting task while driving.

 

Type of Distraction	Change in Risk (Odds Ratio)	Baseline Prevalence
Total cell (handheld)	3.6	6.4%
Cell dial (handheld)	12.2	0.1%
Cell text (handheld)	6.1	1.9%
Cell reach	4.8	0.6%
Cell browse	2.7	0.7%
Cell talk	2.2	3.2%
Total in-vehicle device	2.5	3.5%
In-vehicle device (other, e.g., touchscreen)	4.6	0.8%
In-vehicle climate control	2.3	0.6%
In-vehicle radio	1.9	2.2%
Reading/writing (including tablet)	9.9	0.1%
Reaching for object (other than cell phone)	9.1	1.1%
Looking at outside object	7.1	0.9%
Eating	1.8	1.9%

Note: All odds ratios statistically different from 1 at the 0.05 level of significance.

Source: Dingus et al. (2016).

 

A recent study focused on the relationship between drivers’ handheld cell phone use and subsequent crash involvement. Owens et al. (2018) performed a case-crossover analysis using the SHRP2 NDS data. A total of 566 crashes of varying severity were matched to 1,749 instances of normal driving on variables including the subject driver, weather, time of day, and speed. The use of handheld cell phones in general, and specifically performing tasks with visual and manual elements (such as texting) were significantly associated with increased crash involvement (excluding crashes where the driver was struck from behind). Of the visual-manual tasks, texting was significantly associated with increased crash involvement. The table below presents these changes in crash involvement when using a handheld cell phone relative to driving without performing secondary tasks.

 

Type of Distraction	Change in Risk (Odds Ratio, 95% CI)
Any cell phone use	1.80 (1.06 - 3.07)
Overall visual-manual tasks	2.19 (1.19 – 4.02)
Texting	2.54 (1.18 – 5.50)

Note: All odds ratios statistically different from 1 at the 0.05 level of significance.

Source: Owens et al. (2018).

 

The study also found that increases in crash involvement associated with visual-manual tasks were greater for crashes in free-flow traffic. Rear-end crashes and run-off road crashes were more prevalent in the crash data than other types of crashes; drivers’ visual-manual cell phone interactions were associated with increased instances of both these crash types. Run-off road crashes were also significantly associated with any cell phone use, including reaching for the device, browsing, or answering calls (Owens et al., 2018).

Another naturalistic study was conducted from 2007 to 2015 with approximately 15,000 teen drivers (16 to 19 years old). Videos of 2,229 moderate to severe crashes (vehicle impact forces > 1g) including single- and multi-vehicle crashes were extracted and analyzed (Carney et al., 2018). About 59% involved teen drivers who were distracted in the 6 seconds prior to crashing. The most common distractions included attending to passengers (15%), using cell phones (12%), or attending/reaching inside the vehicles (11%). Over the course of the study duration, there were increases in the proportion of crashes in which the drivers were attending to passengers, attending to objects inside or outside the vehicles, singing/dancing to music, or operating/looking at cell phones (i.e., not talking or listening); whereas crashes associated with behaviors such as talking/listening on cell phone and smoking declined.

Klauer et al. (2014) used a naturalistic study to examine distracted behaviors and their effects on the risk of being involved in crashes or near-crashes among 42 novice drivers. Some of the findings are shown in the table below. Novices were eight times more likely to be involved in crashes or near-crashes when dialing cell phones and seven times more likely to be involved in crashes or near-crashes when reaching for cell phones. While the novice driver study had far fewer participants than the SHRP 2 NDS study above, it demonstrated that the risks posed by  types of distraction are problematic for young drivers just as they are for the general driving population.

Estimated Change in Crash Risk When Engaging in Secondary Tasks, Newly Licensed (Novice) Drivers

Type of secondary task	Change in risk
Using a cell phone
Dialing	8.3
Reaching for phone	7.1
Texting	3.9
Reaching for object (other than cell phone)	8.0
Looking at outside object	3.9
Eating	3.0

Note: All odds ratios statistically different from 1 at the 0.05 level of significance.

Source: Klauer et al. (2014).

 

Given the possible visual, manual, and cognitive attention changes caused by secondary tasks while driving, none of the distractions listed in the tables above is easily addressed. Moreover, it is important to note that many studies on distracted driving and its consequences were conducted prior to the proliferation of smart phones, navigation apps and devices, and built-in technologies. Consequently, it is possible that distraction-related crashes will escalate as the prevalence, diversity, and use of new technologies continues to increase.

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