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J.S. Held Strengthens Forensic Accounting and Financial Investigations Expertise and Expands Suite of Services in Canada with Acquisition of ADS Forensics
Read MoreAccording to the National Highway Traffic Safety Administration (NHTSA), out of the nearly 9.1 million passenger car, SUV, pickup and van crashes which happened in 2010, only 2.1% involved a rollover. In that same year, however, rollovers accounted for nearly 35% of all deaths from passenger vehicle crashes. Given this disparity in statistics, rollover crashes are often the subject of litigation requiring an accident reconstruction. Rollover crashes are complex and unique events that require specific expertise. An accurate reconstruction requires expertise in all three of the phases of a rollover crash:
1) the loss of control phase, where the driver loses directional control of the vehicle,
2) the trip phase, where forces cause the vehicle to tip up and go airborne,
3) the rollover phase, where the vehicle tumbles to rest or tumbles into another object.
J.S. Held experts have performed research and published studies specific to all three of these rollover phases. The following peer-reviewed, scientific publications demonstrate our expertise in rollover accident reconstruction.
Reconstructions of rollover accidents have historically assumed that a rolling vehicle decelerates at a constant rate. However, a constant deceleration assumption can lead to errors in reconstruction of the rollover dynamics. This paper uses a planar vehicle-to-ground impact model to develop an understanding of why a vehicle’s deceleration rate would be expected to vary over the course of a rollover. The paper goes on to develop a linearly decreasing model that can easily be used in practice. The model is validated using real world rollover test data.
This paper explores the use of PC-Crash, a vehicular crash simulation software package, for modeling the dynamics of a dolly rollover test run in accordance with SAE J2114. The authors examine the current capabilities of PC-Crash for rollover modeling and makes suggestions for how the physics-based software package might be improved for modeling rollovers.
This paper examines the use of camera-matching video analysis techniques to quantify the vehicle dynamics and deformation for a dolly rollover test run. This method enables vehicle motion data and deformation measurements to be obtained from video of the event, rather than from onboard data acquisition equipment. The authors discuss how it is shown to be a viable technique for obtaining three-dimensional vehicle motion during a rollover crash test.
This paper examines the accuracy of a planar impulse momentum impact model, which had been previously derived, in representing the dynamics of three vehicle-to-ground impacts that occurred during a SAE J2114 dolly rollover test. The authors discuss selecting impact model parameters which maximize the accuracy of the model.
A rollover crash consists of a series of vehicle-to-ground impacts separated by periods of airborne motion. This paper analyzes the influence of impact conditions on the dynamics and severity of rollover crashes. The authors extend equations that describe the dynamics of an idealized vehicle-to-ground impact and then consider the behavior of these equations under a variety of impact conditions that occur during real-world rollovers.
The ejection of vehicle occupants in rollover crashes is a major source of motor vehicle-related casualties. When analyzing rollover cases, crash investigators are often asked to determine likely occupant ejection scenarios. This paper takes an in-depth look at a two-dimensional particle model that was demonstrated to be a robust method for investigating a wide variety of possible ejection scenarios that can occur in rollover crashes.
This paper explores the dynamics of rollover crashes and examines factors that influence the severity of the roof-to-ground impacts that occur during these crashes. The paper examines 12 real-world rollover accidents that were captured on video. Analytical modeling is used to study the influence that the trip phase characteristics may have on the severity of roof-to-ground impacts that occur during the roll phase. Additionally, an analytical impact model was derived for investigating the mechanics of a roof-to-ground impact.
This paper presents an image analysis of a laboratory-based rollover crash test using camera-matching photogrammetry—the science of measuring 3D objects from images. While the photogrammetric method presented can be a useful tool to extract vehicle roll angle data from test video, it requires further exploration if it is to become a robust post-processing tool for general application to crash safety analysis.
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