1 Validation of a Dynamic Rollover Test Device Mattos G.A., Grzebieta R.H., Bambach M.R., and McIntosh A.S. Transport and Road Safety (TARS) Research, University of New South Wales, Sydney Australia Abstract - The Jordan Rollover System (JRS) is a device designed, with minimal constraints, to simulate a dynamic trip-over rollover crash. It has been shown to perform with a high degree of repeatability in regards to test protocol inputs and vehicle performance outputs and is the test device of choice for three separate research facilities around the world. The performance of a selection of vehicles, as tested on the JRS at the Center for Injury Research, was compared via logistic regression to their real world injury rate in single-vehicle rollovers using police reported crash data. Results indicate that vehicles which experience more roof crush in a JRS test generally experienced higher rates of incapacitating and fatal injury in real world rollover crashes. Keywords: Jordan Rollover System; Roll over; Roof crush; Injury rate; Crashworthiness INTRODUCTION Case-control studies have been performed on data extracted from crash databases to study the relationships between vehicle roof strength and roof intrusion in rollover crashes on one hand and injury incidence and severity on the other hand. In two similar studies Moffatt and Padmanaban [1] and Padmanaban et al. [2] concluded that there was no significant relationship between vehicle roof strength, as measured quasi- statically under the protocol outlined in Federal Motor Vehicle Safety Standard 216 (FMVSS 216), and the likelihood of serious or fatal injury or the amount of roof damage in a rollover crash. They did, however, conclude that vehicles with large amounts of roof damage had higher severe injury and ejection rates. In contrast, other case-control studies [3-5], relying on similar data sets, have found a positive relationship between the amount of roof crush and the likelihood of serious injury in rollover crashes. Brumbelow et al. [6] and Brumbelow and Teoh [7] found that the FMVSS 216 strength-to-weight ratio (SWR), among other metrics derived from the quasi-static test, was a significant predictor of incapacitating injury rate in rollover crashes. They also provided a detailed discussion of the methods used by Moffatt and Padmanaban and explained why their results differed. The reason being that the Moffatt and Padmanaban study failed to control for confounding factors such as crash state, yet controlled for other factors that have built in bias with certain injury levels. A separate study has found that “passenger vehicles with a higher SWR…are likely to experience less vertical roof intrusion in rollover crashes than vehicles with a lower SWR” [8]. Recent work has been done to establish, via mathematical derivation for a specific vehicle design, that the SWR required to limit roof crush to 127 mm (5 in) in a dolly rollover test is 3.6 [9]. Also, there has been a focussed effort to determine the role of roof crush in injury causation in rollover crashes. The results of which indicate that the most injurious events, as observed in various dynamic rollover tests, occur in vehicles with weaker roofs, and greater roof crush [10-12]. Research is currently being undertaken to design dynamic tests and test protocols that would provide a more accurate assessment of a vehicle’s occupant safety in a rollover crash [13-15]. Three versions of the Jordan Rollover System (JRS) are being used at locations around the world (Center for Injury Research (CFIR) in Goleta, CA, USA; University of Virginia in Charlottesville, VA, USA; University of New South Wales/Crashlab in Sydney, NSW, Australia) to study rollover and determine the feasibility of using the JRS to accurately assess a vehicle’s ability to protect occupants in the real world [16]. The rationale for using dynamic tests, in contrast to quasi-static roof strength assessment, is consistent generally with other dynamic crash tests in terms of reflecting the real world crash event, assessing dynamic occupant loads and related injury risks and providing the impetus to improve occupant protection. While dynamic crash tests rely heavily on injury measures from anthropomorphic test devices (ATDs) to assess vehicle performance, only the structural performance of vehicles was assessed for this study. This is because ATDs, and associated injury measures, have yet to be validated for use in a dynamic rollover test. Although the structural performance of a vehicle during a crash may not be as indicative of the injury risk as measures obtained via the use of an ATD, it is often directly responsible for the response of the ATD [10, 11]. The performance of each vehicle’s roof, as tested on the CFIR JRS, was analysed to see if it was associated with its performance in terms of occupant injury in real world single-vehicle rollover crashes.