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Rollover crashes are complex events that generate motions in all six degrees of freedom (6DOF). Directly quantifying the angular rotations from video can be difficult and vehicle orientation as a function of time is often not reported for staged rollover crashes. Our goal was to evaluate the ability of using a match-moving technique and consumer-grade video cameras to quantify the roll, pitch and yaw angles and angular velocities of a rollover crash. We staged a steer-induced rollover of an SUV at 106 km/h. The vehicle was fitted with tri-axial accelerometers and angular rate sensors, and five consumer-grade video cameras (2 on tripods, 2 on drones, 1 handheld, ~30 fps) captured the event. Roll, pitch and yaw angles were determined from the video using specialized software.

Estimation of target-to-background luminance ratios is a powerful method by which human detection of objects can be assessed. In the forensic community, evaluation of the detectability of a pedestrian to an automobile driver is often of interest. With calibration, the modern digital camera employing a CCD or CMOS light collection device can be a convenient and economical luminance estimation tool. Certain CCD or CMOS sensors will linearly report the impinging incident light pixel by pixel over a range of intensities. The device becomes nonlinear at low and high intensities; however, the linear region can be adjusted to the specific lighting conditions of interest by modifying the shutter speed, ISO setting, and aperture size. Image noise, sensor non-uniformity, temperature sensitivity, camera color sensitivity, and the spectral power distribution of the illuminant require treatment for direct comparison to the luminance.

The objective of this study was to assess the accuracy of using high-speed frontal barrier crash tests to predict the impact speed, i.e. equivalent barrier speed (EBS), of a lower-speed frontal barrier crash. Force-displacement (F-D) curves were produced by synchronizing the load cell barrier (LCB) data with the accelerometer data. Our analysis revealed that the F-D curves, including the rebound phase, for the same vehicle model at the same impact speed were generally similar. The test vehicle crush at the time of barrier separation, determined from the F-D curves, was on average 17±16% (N = 150) greater than the reported maximum hand-measured residual crush to the bumper cover. The EBS calculated from the F-D curves was on average 4±4% (N=158) greater than the reported EBS, indicating that using F-D curves derived from LCB data is a reliable method for calculating vehicle approach energy in a crash test.

Quantifying the energy associated with vehicle damage is the basis of common methods used to reconstruct car crashes. This study sought to characterize the relationship between crush and energy for the front and rear surfaces of a passenger car. Nine stationary barrier crash tests and one aligned car-to-car test were conducted using several cars of the same model with impact speeds ranging from 4.3 to 15.2 m/s generating as much as 0.47 m of crush. The results revealed a linear speed-crush relationship for front and rear car surfaces and a restitution coefficient that decreased from a maximum of 0.33 at low speed to a relatively constant value of 0.15 for crush levels above 0.2 m. Crush coefficients derived from the crash tests were compared to the coefficients from three other sources: i) default values from the CRASH3 computer program, ii) values from a published database and iii) values derived from an assumed damage threshold value and an NHTSA high-speed crash test.

Collision data stored in the airbag sensing and diagnostic module (SDM) of 1996 and newer GM vehicles have become available to accident investigators through the Vetronix Crash Data Retrieval system. In this study, two experiments were performed to investigate the accuracy and sensitivity of the speed change reported by the SDM in low-speed crashes. First, two SDM-equipped vehicles were subjected to 260 staged frontal collisions with speed changes below 11 km/h. Second, the SDMs were removed from the vehicles and exposed to a wide variety of collision pulses on a linear motion sled. In all of the vehicle tests, the speed change reported by the SDM underestimated the actual speed change of the vehicle. Sled testing revealed that the shape, duration and peak acceleration of the collision pulse affected the accuracy of the SDM-reported speed change. Data from the sled tests were then used to evaluate how the SDM-reported speed change was calculated.

Crash data stored in the airbag sensing and diagnostic modules (SDMs) of General Motors vehicles can provide useful information for accident investigators. To quantify the accuracy and sensitivity of select 2003 to 2004 SDMs, two types of tests were performed. First, three 2004 vehicles underwent 136 vehicle-to-barrier and vehicle-to-vehicle collisions with speed changes up to 8 km/h. Second, 2003 and 2004 model year SDMs underwent a range of crash pulses using a linear sled. In all of the tests the speed change reported by the SDM underestimated the actual speed change. The speed change underestimates ranged from 0.2 to 2.9 km/h except for several anomalous tests in which the underestimate was as high as 12.3 km/h. The magnitude of this error varied with crash pulse shape. Increasing crash pulse duration and decreasing peak acceleration increased the difference between the actual and SDM reported speed change. The threshold accelerations for the SDMs tested ranged from 1.1 to 2.7g.

Vehicle rollovers are complex events that can be difficult to reconstruct. The goal of this study was to explore whether different vehicle trip models could identify when during the trip phase a vehicle possesses the dynamic conditions needed to rollover. We used three sport utility vehicles (SUVs) with either absent or disabled electronic stability control to conduct six tests involving a steer-induced control loss on a large flat concrete surface. Vehicle kinematics were measured using a GPS speed sensor, tri-axial accelerometers, tri-axial angular rate sensors, and both drone- and land-based video cameras. Four vehicle trip metrics were derived and evaluated using the vehicle dynamics between steer onset and the end of the trip phase. During three tests, one or more of the vehicle’s tires lifted off the ground but the vehicle did not roll. In the other three tests, the vehicle rolled.

Vehicle rollovers generate complicated damage patterns as a result of multiple vehicle-to-ground contacts. The goal of this work was to isolate and characterize specific directional features in coarse- and fine-scale scratch damage generated during a rollover crash. Four rollover tests were completed using stock 2001 Chevrolet Trackers. Vehicles were decelerated and launched from a rollover test device to initiate driver's side leading rolls onto concrete and dirt surfaces. Gross vehicle damage and both macroscopic and microscopic features of the scratch damage were documented using standard and macro lenses, a stereomicroscope, and a scanning electron microscope (SEM). The most evident indicators of scratch direction, and thus roll direction, were accumulations of abraded material found at the termination points of scratch-damaged areas. Abrasive wear mechanisms caused local plastic deformation patterns that were evident on painted sheet metal surfaces as well as plastic trim pieces.

The purpose of this study was to characterize the kinematics of four Chevrolet Tracker rollover tests and to determine their average and intermediate deceleration rates while traveling on concrete and dirt. Single vehicle rollover tests were performed using four 2001 Chevrolet Trackers fitted with six degree of freedom kinematic sensors. Tests were conducted using a rollover test device (RTD) in accordance with SAE J2114. The test dolly was modified (resting height of the vehicle wheels was raised) between tests 1, 2, and 3. The RTD was accelerated to 15.6 m/s (35 mph) and then decelerated rapidly by an energy absorbing crash cushion (EA) to cause the vehicle to launch and roll. The vehicles initially rolled on a smooth concrete surface and continued into loose dirt. This paper adds to the body of work identifying phases of constant deceleration during staged RTD tests and compares these phases to the overall deceleration rate.

The purpose of this paper was to compare the damage to pickup truck bumpers produced by vehicle-to-barrier and vehicle-to-vehicle collisions of a similar severity, in order to determine whether vehicle-to-barrier tests can serve as surrogates for vehicle-to-vehicle tests in accident reconstruction. Impact tests were conducted on the front and rear bumpers of five pickup trucks. Each truck was subjected to an impact with a fixed barrier and with a passenger vehicle. All impacts resulted in pickup truck speed changes of about 8 km/h. Damage produced in the barrier and vehicle-to-vehicle collisions was similar if both collisions resulted in bumper mount damage on the pickup truck. If there was no bumper mount damage, then the bumper beam deformation depended on the shape of the impactor.