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According to the National Highway Traffic Safety Administration, “of the nearly 9.1 million passenger car, SUV, pickup and van crashes in 2010, only 2.1% involved a rollover. However, rollovers accounted for nearly 35% of all deaths from passenger vehicle crashes. In 2010 alone, more than 7,600 people died in rollover crashes.” Rollover accidents continue to be a leading contributor of vehicle deaths. While this continues to be true, it is pertinent to understand the entire crash process. Each stage of the accident provides valuable insight into the application of reconstruction methodologies. Rollover Accident Reconstruction focuses on tripped, single vehicle rollover crashes that terminate without striking a fixed object.

The rear override crash behavior of full-size and light duty pickup trucks was examined. A series of ten full-scale, front and rear override impact crash tests were conducted involving four full-size pickup trucks, two light duty pickup trucks, and one sport utility vehicle (SUV). The tests were conducted utilizing a fabricated steel rigid barrier mounted on the front of the Massive Moving Barrier (MMB) test device with full overlap of the test vehicle. Crush ranged from 25.0 to 77.9 inches for impact speeds of 21.7 to 36.0 mph. These override tests on pickups were conducted to provide more basis in an area that is underrepresented in the literature. Each test was documented and measured prior to, and following, the crash test. The stiffness parameters were calculated and presented using constant stiffness, force saturation, and the power law damage models.

Snowmobile acceleration, braking and cornering performance data are not well developed for use in accident reconstruction. Linear acceleration and braking data published by D'Addario[1] gives results for testing on 4 snowmobiles of various make and model. This paper presents the results of on-snow tests performed in 2014 which include acceleration and cornering maneuvers that have not been published previously. Maximum and average cornering speeds and corresponding lateral accelerations are presented for turns of radius 20, 35 and 65 feet (6.1, 10.7 and 19.8 meters) on level, packed snow. Performance values for acceleration, braking, and cornering are determined in tests with and without a passenger. Results of linear acceleration and braking tests were found to be comparable to the previously published work. The data are useful in snowmobile accident reconstruction for certain types of snowmobile motion analyses.

A follow-up case study on rollover testing with a single full-size sport utility vehicle (SUV) was conducted under controlled real-world conditions. The purpose of this study was to conduct a well-documented rollover event that could be utilized in evaluating various methods and techniques over the phases associated with rollover accidents. The phases documented and discussed, inherent to rollovers, are: pre-trip, trip, and rolling phases. With recent advances in technology, new devices and techniques have been designed which improve the ability to capture and document the unpredictable dynamic events surrounding vehicle rollovers. One such device is an inertial measurement unit (IMU), which utilizes GPS technology along with integrated sensors to report and record measured dynamic parameters real-time. The data obtained from a RT-4003 IMU device are presented and compared along with previous test data and methodology.

A follow-up study on rollover testing was conducted along a section of a remote rural highway using six full-size sport utility vehicles (SUVs) of differing makes and models. The vehicles were instrumented and towed to highway speeds before being released, at which point an automated steering controller steered the vehicles through a series of maneuvers intended to result in rollover. A total of eight tests were conducted and documented, six rollovers and two non-rollover events. The six rollover events provide trip and tumbling conditions for each vehicle. The two non-rollover attempts produced cornering tire marks and allowed for the documentation of near roll conditions for the two out-of-control vehicles. All eight tests presented are instrumented real-world type tests that were later correlated based upon the data obtained.

Three full-size sedans were towed to highway speeds along a section of a remote rural highway. Upon release, an automated steering controller steered the vehicles through a series of maneuvers intended to result in rollover. Repeated attempts to roll each vehicle were made until rollover resulted. Non-rollover attempts produced cornering tire marks by the out-of-control vehicle. Out of numerous runs, 3 rollover and 2 non-rollover tests were selected for documentation and analysis. One additional steer-induced rollover test is presented that was conducted along a simulated road section at a closed test-track facility. All six tests presented are instrumented real-world type tests that were later reconstructed based upon the data obtained from on-board instrumentation, videotape, survey measurements, and still photographs obtained of each respective test.

Nine crash tests were conducted at various speeds on three vehicles in three locations under conditions that resulted in similar damage. The objective was to study the differences in crash pulse, deltaV, crush depth, and impact location with change in closing velocity from 20 to 55 mph. Three equal-weight Nissan Sentra vehicles were impacted in the front, rear, and side by an associated narrow object impact device. The three impactors were identically shaped, flat-faced, one-foot wide, and rigid; but each was designed to have a different weight (light, moderate, and heavy weight). The heavy, moderate, and light weight impactors collided with their associated test vehicle at low, medium, and high impacting speeds, respectively, in order to produce damage corresponding to a 20 mph BEV (Barrier Equivalent Velocity) in all nine tests. Impacts at the same location on the three vehicles produced nearly identical damage yet substantially differed in deltaV.

Crash behavior in narrow object impacts was examined for the perimeter of a 4-door full size sedan. Additional test data was obtained for this vehicle by impacting four sedans with a rigid pole mounted to a massive moving barrier (MMB) in the front, right front oblique, right side, and rear. The vehicles were stationary when impacted by the MMB. Two of the four cars were repeatedly impacted with increasing closing speeds in the front and side, respectively. Each test was documented and the resulting deformation accurately measured. The stiffness characteristics were calculated for the perimeter of car and were presented using the power law damage analysis model. The vehicle's crash performance in these pole tests was compared to that of NHTSA's flat fixed barrier tests (deformable and non-deformable) for the front, side, and rear of this vehicle.

Damage analysis methods in accident reconstruction use an estimate of vehicle stiffness together with measured crush to calculate crush energy, closing speed, and vehicle delta-V. Stiffness is generally derived from barrier crash test data. The accident being reconstructed often involves one or more conditions for which vehicle stiffness is not well defined by existing crash tests. Massive moving barrier (MMB) testing is introduced as a tool to obtain additional and accident specific stiffness coefficients applicable for reconstruction. The MMB impacts a stationary vehicle of similar structure as the accident vehicle under accident-specific conditions like impact location, angle, over-ride / under-ride, offset and damage energy. A rigid or deformable structure is mounted to the front of the MMB, representative of the impacting structure in the accident. Four illustrative tests are presented.

Given two or more photos of an accident vehicle (non-stereo pairs such as police photos) an estimate of the deformation (crush) of the vehicle may be obtained by application of camera reverse-projection, using two or more cameras and an exemplar vehicle. A single camera technique familiar to accident scene investigators is modified for this application. The methodology is described within the context of an experiment comparing results obtained by camera reverse projection to actual measured crush. A method of displaying crush results known as “displacement vectors” is presented and examples are illustrated. The technique has been found useful for measurement of 3-dimensional crush.