Effectiveness of Distracted Driving Countermeasures: An Expanded and Updated Review of the Scientific and Gray Literatures

Introduction

In 2019, the AAA Foundation for Traffic Safety conducted a review of the then-current scientific literature concerning the effectiveness of existing and emerging countermeasures against distracted driving. In general, this review found that some studies have shown promising results; however, across the different types of countermeasures, there are many instances of nuanced or mixed outcomes, questionable generalizability to other populations or regions and, in other cases, insufficient evidence to draw firm conclusions. The 2019 review focused only on those studies that included safety or behavioral measures, such as the occurrence of crashes, observed or self-reported behaviors, or objective measures of driving performance.

Based on this review and an expert workshop that was convened in September 2019, there was a need to continue to examine distraction countermeasures, adopting more inclusive criterion and going beyond the peer-reviewed scientific literature. The specific objectives of this follow-up work are as follows:

• To review and update the relevant scientific literature published since the 2019 review with new studies looking at the efficacy of existing and/or novel countermeasures on safety-based measures.
• To consider the current state of knowledge regarding studies that have included non-safety based measures in evaluating the efficacy of countermeasures.
• To document and characterize available smart-phone based apps, products, or services aimed at mitigating driver distraction.

Methodology

Literature Search

A search for scientific literature published since May 2019 was conducted in April 2021 using the same databases and search terms as in the previous review of sources published between 2010 and April 2019. The inclusion criteria from the previous review were expanded to include sources that were previously excluded. As in the previous review, we excluded summary reports corresponding to full reports returned in our searches, and review articles were scanned for relevant references to add to our results.

The initial search yielded more than 5,000 references. All titles and abstracts were reviewed for inclusion by two independent reviewers. In addition, we reviewed the titles and abstracts of references that were deemed relevant to the topic of distracted driving but excluded from the 2019 review in light of the newly added inclusion criteria.

For the final set of articles, key information was distilled and summarized in tabular form using the abstract and/or full article as necessary. The information entered into the tables included the countermeasure type(s), a description of the countermeasure, target behavior(s), study sample, study design, main outcome measure(s), results, notes (if applicable), and reference (source).

App/Product Search

Internet searches, along with searches of the Apple App and Google Play stores, were carried out in March and April 2021 in order to identify apps or commercial products aimed at mitigating distracted driving. Search terms included various combinations of (a) drive, driver, driving, and (b) distract, distracting, distraction, cell, phone. Additional searches added other related terms: (c) safety, prevention, blocking. Relevant apps were identified by a manual review of the search results. The final set of apps or products was catalogued according to a variety of features, including system platform, type of mechanism (e.g., driver monitoring, cell blocking), and timing of feedback, among others. This information was gleaned, as much as possible, from the app store pages as well as the developer’s websites.

Results

A total of 72 articles were entered into Summary Tables, with one table for references reflecting the original inclusion criteria and a second for references reflecting the added inclusion criteria. The results are summarized by countermeasure type (educational and/or behavioral, legislative and policy, enforcement, and technological) and the reader is encouraged to refer to the Summary Tables for more comprehensive presentation of the relevant studies.