Over the years, engineers have introduced improvements in roadway design to reduce the severity and frequency of roadway departure crashes. Similarly, the automotive industry has improved vehicle structure, improved restraint systems, and introduced technologies to help prevent these crashes. However, limited research has explored the interaction between strategies for safer roads and new technologies in the vehicle fleet. There is an opportunity to identify ways in which these advancements can complement each other.

In the United States, automakers entered into a voluntary agreement to make automatic emergency braking (AEB) standard across all models beginning in 2022. AEB has been shown to be highly effective in preventing front-to-rear collisions, with an estimated 50% reduction in those crashes. While AEB systems are primarily designed for vehicle-to-vehicle collisions, they could also activate and significantly reduce speed prior to impact with roadside hardware.

Other vehicle technologies, such as lane departure warning (LDW) and lane keeping assist (LKA), are intended to prevent roadway departures. However, LDW and LKA have not demonstrated the same real-world benefits as AEB, nor have they achieved the performance levels predicted in simulation studies.

By contrast, rumble strips—which provide a haptic and audible warning similar to LDW systems—have been shown to be highly effective in reducing roadway departure and head-on crashes. This raises important questions: Are there changes to roadside features (e.g., lane markings, shoulder width, clear zone width, centerline width) that could improve the effectiveness of LDW and LKA systems to levels comparable to rumble strips? Do these systems lead to an overall reduction in departure and impact angles prior to roadside crashes?

There is a need to investigate how vehicle technologies influence impact speed and angle in roadside crashes, as well as to determine whether updates to Manual for Assessing Safety Hardware (MASH) testing and evaluation criteria are warranted. Additionally, identifying road and roadside features with the potential to enhance the performance of current active vehicle safety systems could support roadside safety design practitioners and transportation agencies in updating policies and standards related to roadway design and roadside hardware—ultimately increasing the safety of the traveling public.

The objectives of this research are to identify potential positive or negative interactions between roadside designs and vehicle crash avoidance technologies, investigate how vehicle technologies could affect impact speed and angle in roadside crashes, and determine any relevant updates to MASH testing and evaluation criteria.