Graeme F. Fowler

Vehicle Rollover Testing, Methodologies in Recreating Rollover Collisions

Rollover crashes are complex events with many factors influencing the initiation of the rollover and the subsequent motion of the vehicle. There exists a need for testing methods that can accurately replicate conditions that happen in real-world rollovers. This chapter, from a comprehensive text on occupant and vehicle responses in rollovers, presents two testing methodologies that consider how to create rollover tests that closely mimic a specific accident scenario and thus that are useful in accident reconstruction and evaluation of vehicle performance in specific situations. The authors describe the development of the Roller Coaster Dolly (RCD), a text fixture that can release a vehicle at speed onto flat or sloping terrain with any desired initial roll, pitch, and yaw angle. The authors also describe a test methodology that utilizes a crashworthy steering controller. This method can replicate and study the entire crash sequence of an on-road maneuver-induced rollover. The authors describe and illustrate (photographs) the use of both tests, concluding that these tests expand the realm of rollover collision scenarios that can be recreated by testing.

Evaluation of Potential Safety Modifications by Review of Accident Reports

Analysis of accident data for consumer products can be used to identify accident modes and to aid in decisions about the feasibility of safety interventions for reducing risk. Decisions based upon a large accident data set, rather than upon a single accident, are much more likely to address important problems and to avoid creating negative consequences (e.g., increases in other kinds of accidents, loss in product utility). This paper describes the application of accident report analysis to a proposed safety intervention for all-terrain vehicles (ATVs). In order to evaluate the suggested use of conspicuity flags as standard equipment on all ATVs to prevent collision-related accidents, we reviewed 287 operating-ATV-associated “In-Depth Investigations” (conducted by the Consumer Product Safety Commission for ATV-associated injuries reported by the National Electronic Injury Surveillance System during a 2.5 month period in 1985). It was found that flags could have influenced only a very small portion of ATV injuries at best, and might even have a null or negative net impact when problems are considered. Thus, required usage of flags would be inappropriate for most riding environments.

Single-Vehicle Rollovers Involving an Initial Off-Roadway Excursion Followed by a Return to Roadway: A NASS Study and Vehicle Response Measurement

This paper will describe an investigation that seeks to understand how rollovers occur in real-world crashes, both by studying real-world crashes and by analyzing vehicle-handling tests to gain insights into potential mechanisms of pre-crash loss of control. In particular, this study focuses on one type of rollover, namely single-vehicle rollovers that follow a pattern of the vehicle first leaving the roadway and then returning to the roadway typically out-of-control. The aims of this study included the following: (1) to describe the frequency and characteristics of single-vehicle rollovers involving an off-roadway excursion followed by a complete, if only temporary return to the roadway; (2) to the extent possible, given available data, to assess the nature and consequences of driver inputs during the crash sequence; (3) to define characteristics of crash scenarios which include a substantial proportion of this subset of single-vehicle rollovers. In order to accomplish these aims, case files from the National Automotive Sampling System, Crashworthiness Data System (NASS CDS, 1997-2001) were reviewed. The overall purpose of this review was to understand the mechanisms involved with loss of control and provide this information to support further research on preventing loss of control on the roadway subsequent to off-roadway excursion and roadway reentry. To further illustrate the mechanism that leads to loss of control when a vehicle returns to the roadway, the results of testing conducted to compare a vehicles response to steering maneuvers on pavement versus the same steering maneuvers initiated on a road edge is presented. This paper presents the results of these tests, focusing on the effect that the change in surface has in amplifying the yaw rate and sideslip response of the vehicle. Finally, the results of the testing are compared to the insights gained from the NASS CDS real-world crash study, to garner further insight into some of the mechanisms involved with this type of accident.

Average Operator Inaction Characteristics with Lever Controls — Study of the Column Mounted Gear Selector Lever

Sixty drivers executed 1800 automotive transmission shifts from DRIVE to PARK. These shifts were performed in a total of six vehicles. Among analoq data recorded during each shift are longitudinal (pull) and rotational forces and rotational position of the lever. Analysis reveals that drivers typically impact the mechanical stop associated with PARK position with approximately one and one-half times the minimum force required to complete the shift. Shifts to PARK are completed in an average of 0.58 seconds, and an additional 0.83 seconds is spent continuing to apply force to the lever after PARK position is achieved. Most (80%) shifts are executed without regard for intervening detents. Those drivers who show hesitation in movement typically hesitate for 50 milliseconds. Whether a driver shifts continuously or with shortduration hesitation appears to be driver style or insert plate impact, independent of vehicle.

An Examination of Motorcycle Antilock Brake Systems (ABS) in Reducing Crash Risk

To prevent wheel lock up (and possible loss of control and capsize) during hard braking motorcycle manufacturers have equipped motorcycles with Antilock Brake Systems (ABS) either as an option or as standard equipment. Several studies utilizing real-world crash data have been published which estimate the effectiveness of motorcycle ABS in reducing the risk of a crash based on varying assumptions. These investigations have reported mixed results.The present investigation relies upon the Fatality Analysis Reporting System (FARS) and the Florida police-reported crash databases to further investigate the effectiveness of motorcycle ABS by expanding upon and refining previous approaches. Notably a case-control approach is used whereby crashes involving ABS- and non-ABS-equipped motorcycles are divided into five groups with a varying likelihood that ABS will affect the risk of crashes in that group. The group of crashes with the least likelihood of being influenced by ABS is considered the control group and used as a measure of exposure to crashes. This methodology attempts to reduce any selection biases that might exist in the two motorcycle classes.The results support the hypothesis that ABS is effective in reducing the crash risk in some crash types. However, it was found that the case-control approach does not incorporate all factors that might influence the overall effectiveness of ABS, for example, motorcycle class and operator age. Accounting for these additional factors would likely require the use of regression analyses and would benefit significantly from additional data.Copyright

Testing and Analysis of Autonomous Emergency Braking Systems Using the Euro NCAP Vehicle Target

Passenger cars are increasingly available equipped with Autonomous Emergency Braking (AEB). AEB systems detect likely forward collisions and apply the vehicle’s brakes if the driver fails to do so, reducing vehicle speed in order to mitigate or potentially avoid a collision. The performance of these systems is experimentally evaluated in tests including those specified by the European New Car Assessment Program (Euro NCAP) and by the Insurance Institute for Highway Safety (IIHS). In both of these testing programs the subject vehicle is driven towards a Euro NCAP Vehicle Target, an inflatable device designed to have visual and radar reflective characteristics similar to the rear of a compact car.The results reported by Euro NCAP and the IIHS have revealed significant differences in the AEB test results achieved by various AEB-equipped vehicles. Such differences exist even between vehicles with similar sensing technologies, suggesting that the source of such disparities may be differences in sensor data processing methods or differences in collision mitigation and avoidance strategies. This paper details the performance of AEB as well as Forward Collision Warning (FCW) systems when tested with the Euro NCAP Vehicle Target. These results are analyzed, exploring the differences in the performance of these systems under the test conditions and discussing possible reasons for the observed disparities.Copyright

An Examination of Motorcycle Antilock Brake Systems in Reducing Crash Risk

To prevent wheel lockup (and possible loss-of-control and capsize) during hard braking, motorcycle manufacturers have equipped motorcycles with antilock brake systems (ABS) either as an option or as standard equipment. Several studies utilizing real-world crash data have been published, which estimate the effectiveness of motorcycle ABS in reducing the risk of a crash based on varying assumptions. These investigations have reported mixed results. The present investigation relies upon the fatality analysis reporting system (FARS) and the Florida police-reported crash databases to further investigate the effectiveness of motorcycle ABS by expanding upon and refining previous approaches. Notably, a case-control approach is used, whereby crashes involving ABS- and non-ABS-equipped motorcycles are divided into five groups with a varying likelihood that ABS will affect the risk of crashes in that group. The group of crashes with the least likelihood of being influenced by ABS is considered the control group and used as a measure of exposure to crashes. This methodology attempts to reduce any selection biases that might exist in the two motorcycle classes. The results support the hypothesis that ABS is effective in reducing the crash risk in some crash types. However, it was found that the case-control approach does not incorporate all factors that might influence the overall effectiveness of ABS, e.g., motorcycle class and operator age. Accounting for these additional factors would likely require the use of regression analyses and would benefit significantly from additional data.

Full-Scale Moving Motorcycle into Moving Car Crash Testing for Use in Safety Design and Accident Reconstruction

In its normal course of business, Exponent conducts many accident investigations and crash tests related to motorcycles for a range of clients. The knowledge gained from these investigations, as well as internally funded research, is used to continually improve testing methods and accident reconstruction techniques for the analysis and investigation of motorcycle design issues and accidents. Four publications described below provide examples of Exponents continuing interest in motorcycle testing and crash and safety analysis. Published data indicate that prior studies of motorcycle accidents and the advancements in motorcycle safety designs have been based, in large part, on single‐moving‐vehicle crash tests. However, as described in this paper, the accuracy of the post‐ impact motion of the motorcycle and automobile is important for evaluating the kinematics of the motorcycle rider. For two‐moving‐vehicle accidents, the rotation of the motorcycle front wheel and the resulting asymmetric compression and deformation of the front forks affects the post‐impact motion of the motorcycle rider and the crash damage observed on the motorcycle and the other vehicle. Consequently, it is preferable to conduct two‐ moving‐vehicle crash tests when the post‐impact kinematics are important to an analysis. Exponents Test and Engineering Center has been conducting crash tests of moving motorcycles into moving cars for many years and has developed reliable methods for conducting such tests across a wide variety of speeds and impact orientations (Fig. 1). Fig.1. Vehicle line‐up in preparation for two‐moving‐ vehicle crash test Conducting such tests has rendered a broad understanding of the post‐impact motion of the motorcycle, the kinematics of the rider, and the post‐crash damage available for analysis when a motorcycle is involved in a two‐moving‐vehicle impact. This paper presents the test methods used and a selection of the results derived from a series of crash tests involving moving motorcycles colliding with moving cars (e.g., Figs. 2 and 3). The featured tests were conducted at speeds representing both urban and highway travel and provide data that is useful in evaluating crash events with variations in the impact angle and initial point of contact between vehicles.