Pedestrian Safety: Assessment of Crashworthiness Test Procedures

Hu, Jingwen; Lin, Yang-Shen; Boyle, Kyle J.; Bonifas, Anne; Reed, Matthew P.; Gupta, Vishal; Lin, Chin-Hsu · 2023 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This study addresses the lack of objective methods for assessing active pedestrian safety systems, specifically pop-up hoods, within U.S. regulatory frameworks. While European protocols like Euro NCAP use computer simulations to determine Head Impact Time (HIT) for pop-up hood deployment validation, these rely on Generic Vehicle (GV) models based on European geometries. This approach is unsuitable for U.S. vehicles, which feature a higher prevalence of larger SUVs and pickup trucks with distinct front-end shapes. Furthermore, U.S. Federal Motor Vehicle Safety Standards require independent enforcement testing, making manufacturer-provided simulation data problematic. The research aimed to develop prediction models for HIT using measurable vehicle front-end characteristics and to evaluate how pop-up hood design parameters affect pedestrian injury risks, particularly regarding hood collapse. The researchers conducted a multi-phase study involving literature reviews and finite element (FE) simulations. First, they identified variables affecting HIT, such as impact speed, vehicle geometry, and pedestrian size. For the simulation phase, they morphed Euro NCAP GV models into 20 U.S. vehicle front-end geometries to create a representative database. They performed 240 pedestrian impact simulations using four pedestrian body sizes (6-year-old, small female, midsize male, and large male) at three impact speeds (30, 40, and 50 kph). These simulations generated a virtual database used to develop statistical prediction models for HIT, head contact velocity, and head contact angle. Additionally, the study simulated hood edge impacts and parametric variations in pop-up hood designs to assess structural performance under pedestrian kinetic energy. The results demonstrated high correlations and good accuracy in the developed prediction models for HIT and associated kinematic variables. The simulations revealed that pop-up hoods could collapse under the kinetic energy of a pedestrian, particularly depending on the pedestrian's size and the hood's design. Actuator stiffness at the time of head contact was identified as the most critical parameter for preventing hood collapse. Because larger pedestrians impart higher kinetic energy, the deployment system must be designed to withstand the forces from the largest pedestrian stature to avoid collapse. However, designing for the largest pedestrian slightly increased the Head Injury Criterion (HIC) for smaller pedestrians, though injury levels remained lower than those associated with undeployed hoods. The significance of this work lies in providing an objective, geometry-based method for predicting HIT, which can facilitate the integration of pop-up hood assessments into U.S. safety standards without relying on manufacturer-specific simulations. The findings offer specific design guidelines for pop-up hood actuators, emphasizing the need to balance collapse prevention for large pedestrians with injury mitigation for smaller ones. This research bridges a critical gap in pedestrian safety evaluation, offering a pathway for regulating active safety systems that account for the diverse vehicle fleet in the United States.

Key finding

Actuator stiffness at the time of head contact is the most critical design parameter for preventing pop-up hood collapse, necessitating deployment systems designed for the largest pedestrian stature to ensure safety across all sizes.

Methodology

modeling

Sample size: 240

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• vru crash typology

Information type

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• Empirical Findings: crash risk outcomes