Driver Behavior in the Presence of E-scooters versus Bicyclists

Abstract: Despite the increasing popularity of electric scooter (e-scooter) programs in many United States cities, research on e- scooter riding safety risks and the impact of infrastructure on driver behavior is limited. This research includes a driving simulator study to explore the impact of attitudes towards micromobility users on driver behavior in the presence of e-scooter riders versus bicyclists.

This study first summarizes recent research findings related to e-scooter safety and explores literature on drivers’ attitudes towards e-scooter riders and bicyclists and related behaviors as well as the impact of infrastructure where e-scooter riders and bicyclists ride on, on driver behavior. The review of bicycle-related literature is done to fill gaps in understanding e-scooter safety by drawing parallels between e-scooters and bicycles and driver attitudes and behaviors towards their users. The review of the literature indicates that there are correlations between e-scooter riding location with frequency and severity of e-scooter crashes. In addition, it reveals e-scooter rider preferences with respect to riding surface and infrastructure type.

The driving simulator experiment included participants driving through seven different scenarios that varied in the type of the micromobility user (e-scooter rider or bicyclists) that was present and the type of riding surface (conventional bike lane, travel lane, or sidewalk for e-scooter riders only). In addition, participants were asked to complete a questionnaire targeted at understanding their attitudes towards bicycling and e-scoter riding. A total of 42 participants were recruited and their data were analyzed.

Questionnaire results show preferred infrastructure treatments to be bike lanes or sidewalks. From the rider and driver perspective, more preferred sidewalk for e-scooters and more preferred bike lanes for bicyclists. Statistical analysis of the attitudinal questions revealed a more negative bias towards e-scooter riders. Participants perceived the use of public funds for bicyclists as more beneficial than for e-scooters and cared more about their personal or perceived perception as a bicyclist than e-scooter rider.

The driver performance results revealed lower speeds with less separation from e-scooter riders and greater maximum lateral distance changes when e-scooters rode in the travel lane compared to the sidewalk. The presence of bicyclists resulted in greater maximum lateral distance changes in the travel lane than in the bike lane. Faster driver speeds were also observed for the scenario with a bicyclist in the travel lane than the scenario with an e-scooter rider in the travel lane. Overall, the presence of micromobility users was found to induce lower speeds but the presence of bicycle infrastructure alone was not found to affect speeds. Lastly, bicycling or e-scooter riding frequency as well as agreement with most attitude statements was not found to affect driver behavior. When analyzing correlations between driver behavior and attitudes towards e-scooters and bicycles, we found that drivers who agree that e-scooter riders should have passed an operating test maintain a larger lateral distance changing than those who disagree.

Ultimately, this research contributes to a clearer understanding of interactions to inform infrastructure design and other countermeasures to safely accommodate vulnerable e-scooter riders.