Safety Impacts of Lead Vehicle Behavior on Drivers’ Decisions to Slow Down and Move Over

Introduction

Fatal and serious injuries resulting from roadside struck-by incidents continue to be a prevalent safety issue. Although all 50 states and the District of Columbia have some version of a Slow Down, Move Over Law (SDMO), driver understanding and compliance with SDMO laws are inconsistent. Both slowing down and moving over help to reduce an individual motorist’s risk of striking a roadside worker, but these actions may have different impacts on the behavior of other drivers upstream. There is currently little to no evidence to base an informed recommendation on which of these two actions is most optimal for SDMO requirements. This project seeks to explore if and how upstream driver SDMO behavior is impacted by the behavior of a lead vehicle.

Project Goal and Plan

This research project will review and synthesize literature on the relative safety benefits of drivers slowing down or moving over in their approach of a roadside scene where SDMO action is required. Then, a controlled experimental study will be conducted in the AAA Foundation Driving Simulation Laboratory to examine how drivers’ decisions are influenced by the actions of other drivers in relevant scenarios. Findings will guide outreach to motorists about safe driving around roadside incidents, and may help inform refinements of SDMO laws.