Objective:​ One means of protecting pedestrians is through vehicle safety systems that are built into a vehicle’s front-end to protect pedestrians should a vehicle impact occur. These pedestrian protection systems include hood structures aimed at reducing pedestrian head injuries. Pop-up hoods function by increasing the head penetration space beneath the hood by quickly lifting upon vehicle contact with a pedestrian. This paper explores the prevalence of vehicles with pop-up hoods to show that their market penetration and performance benefits merit consideration in standardized pedestrian protection test protocols.

Methods:​ Euro NCAP test scores and the Parkers United Kingdom (UK) vehicle database were used to better understand the fleet performance and market penetration of vehicles with pop-up hoods. An analysis of Euro NCAP pedestrian test results and overall vehicle test scores was performed to compare the performance of vehicles equipped with pop-up hoods to those without, and the Parkers UK vehicle database was used to estimate historical vehicle prices and demonstrate that pop-up hoods are available on both high- and low-cost vehicles.

Results:​ There are many different types of systems that operate pop-up hoods, and their architectures vary widely from one vehicle to the next;​ however, they typically create an increase in the distance from the hood to rigid componen ts in the engine bay, thus reducing the probability and/or severity of a head injury of a struck pedestrian. Compared to vehicles with non-deploying hoods, vehicles with pop-up hoods rated by Euro NCAP had better pedestrian protection scores on average. In the European Union (EU), pop-up hood systems, which have become more prevalent over time, were found on vehicles outside the oft-assumed market of only low-volume luxury models.

Discussion and Limitations:​ Pedestrian Protection is mandatory on all vehicles sold in the EU Conformity of pop-up hoods is based largely on headform impact tests conducted on a fully popped-up hood. During the Type Approval process, the determination of system reliability and consistency also must be demonstrated by the vehic le manufacturer, but the means and requirements to do so are not defined within the regulation itself. Because the operation of pop-up systems varies widely and they are generally unique to specific vehicle models, the demonstration of system functionalit y is agreed upon between the manufacturer and the Type Approval Authority. Euro NCAP operates in a similar manner.

Conclusions:​ Pop-up hoods generally perform better than non-deploying hoods in headform impact tests. As their development matures and vehicle styling progresses towards low, sleek, aerodynamic hood profiles, demand as well as variation in these systems may grow. To date there is not a published, fully prescriptive test protocol that tests the full functionality of such systems, including reliability and deployment thresholds, to objectively ensure that they function properly during an actual collision with a pedestrian.