To What Extent Do Certain Cell Phone Tasks Decrease Driver Performance and Increase Crash Risk? An Overview Review of Meta-analyses and Naturalistic Studies

Author(s): Caird, Simmons

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Abstract:

Background/Context: Certain smart, mobile and cell phones tasks such as texting and reaching for a phone increase unsafe driver behaviours, injuries and fatalities, whereas the effects for other tasks such as voice recognition and social media interaction are less certain or unknown. Patterns of cell phone use have evolved as functionality has increased. As different cell phone functions are used by drivers, research on the impact of specific cell phone distractions on safety has attempted to keep pace.

Aims/Objectives: The purpose of this overview review was to synthesize the highest quality evidence on the adverse effects of cell phones from meta-analyses and naturalistic studies on driving performance and crash risk. Meta-analyses statistically combine effect sizes from studies that address cell phone use in driving simulators and on test tracks. Results from meta-analyses provide a high-level of evidence about the specific effects of cell phone tasks on driving performance such as lateral and longitudinal control and emergency response. Naturalistic driving studies observe the behavior of drivers in their own vehicles by means of cameras and vehicle sensors over a span of many months or years and these observations permit a detailed understanding of the behavior of drivers leading up to crashes and near-crashes.

Methods/Targets: A number of databases including Google Scholar, MEDLINE, Trid and were searched for systematic reviews and meta-analyses on the effects of cell phone tasks on either driving performance or crash risk through October 2018. The quality of included meta-analyses and systematic reviews were evaluated using the AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews) checklist. In addition, a systematic search for naturalistic driving studies was updated from a previous meta-analysis with a SHRP-2 study on secondary task crash risks.

Results/Activities: The quality of included meta-analyses, systematic reviews and naturalistic studies varied depending on adherence to known methodological assessment criteria. The effects of texting, dialing, reach/locate/answer, browse internet, talking, interaction with a music and voice commands on driving performance (i.e., reaction time, detection, lateral position, longitudinal control, eye movements and collisions) and crash risk (odds ratio, 95% confidence interval) were synthesized and illustrated. For example, typing and reading texts increases crash risk by about 10 times (10.3, 2.4-44.7) and negatively affects most measures of driving performance. In addition, drivers, on average, spend about two percent of their time texting while driving. The overall safety risk of a driver is determined by which cell phone tasks are used, crash risk and exposure.

Discussion/Deliverables: Texting, dialing, reaching for a device, internet browsing and talking on cell phones adversely affect driver behavior and increase the probability of being in a crash. Selecting music and speaking voice commands to a cell phone affects driver behavior and may increase crash risk, but additional research is needed.

Conclusions: To interact with apps such as Facebook, Snapchat, Twitter and Instagram, drivers must repeatedly look away from the roadway and these interactions likely decrease driving performance and increase crash risk. Interaction with apps while driving has not been sufficiently studied.