NCHRP's "Evaluation & Comparison of Roadside Crash Injury Metrics" evaluates existing roadside crash injury metrics and proposes enhanced crash injury data that better reflect the occupant characteristics and vehicle fleet of the 2020s.

The crash performance of roadside safety hardware, such as guardrails, is typically evaluated using full-scale crash tests with vehicles striking the device in representative worst-case impact scenarios. Each test is evaluated based on vehicle response, device response, and potential for injury to vehicle occupants. In the U.S., roadside hardware crash tests are conducted according to procedures outlined in AASHTO's Manual for Assessing Safety Hardware (MASH).

The assessment of occupant risk is crucial, as the purpose of these devices is to minimize occupant injury. Unlike vehicle crashworthiness testing, an anthropomorphic test device (ATD; i.e., crash test dummy) is not used to assess occupant risk in crash tests involving roadside hardware due to the oblique nature of roadside impacts and the significant cost increase of ATDs for crash testing. As an alternative, the potential for occupant injury is assessed through metrics derived from vehicle kinematics measured during the crash test. MASH procedures currently assess occupant risk using the simplified point-mass flail space model (FSM).

Despite significant changes in passive safety and vehicle design since the inception of these metrics, the current roadside hardware occupant risk procedures have remained essentially unchanged for nearly 40 years. The goal of this NCHRP research was to evaluate existing roadside crash injury metrics and propose enhanced crash injury metrics that better reflect the occupant characteristics and vehicle fleet of the 2020s.

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