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With commercial availability of the Bosch Crash Data Retrieval Tool (CDR), the information stored in vehicle Event Data Recorders (EDRs) has increasingly been used to supplement traditional traffic crash data collection and reconstruction methods, allowing enhanced confidence levels in transportation safety research. The objective of this study was to assess the accuracy and reliability of EDR data images obtained with the Bosch CDR tool by comparing them to a known crash impulse. Multiple EDRs and necessary sensor arrays were mounted on a HYGE™ acceleration-type crash simulation sled system at various orientations representing different principal direction of force (PDOF) angles and subjected to controlled “crash” impulses, simulating a “deployment event” (DE) and triggering data to be saved in the EDRs. The data included in each EDR's CDR report was compared to the known conditions of the impulse.

Prior to the widespread implementation of ABS brake technology in light vehicles, driver training often included instruction to “pump the brakes” to avoid locking the wheels. Many driver education programs now recommend maintaining high brake pedal force and relying on ABS. It is sometimes asserted that drivers desiring to stop a vehicle quickly still “pump the brakes”. Investigators sought to understand whether drivers desiring to decelerate quickly pump the brakes, especially in a way that may deplete the vacuum stored in a vehicle's brake booster if so equipped, or whether they apply the brakes in a manner corresponding to their desired deceleration. The National Highway Traffic Safety Administration (NHTSA) conducted a testing program to examine driver braking behavior in crash avoidance maneuvers.

Tire failures, including tread belt detachments, have been associated with loss of control crashes including rollovers. Numerous reasons exist for control loss including forces created by the failed or failing tire, cornering capacity diminishment for the detreaded tire combined with control demands beyond the remaining capacity of the vehicle and inappropriate driver demands including excessive steering. Extensive studies have been completed to define the various causes of control loss and to identify risk-reducing countermeasures. These studies have included reconstructions of crashes and tests of real vehicles in test track environments with tires purposely caused to fail.

Understanding and measuring a vehicle's response to cyclical vertical inputs is fundamental to evaluating suspension tuning and handling characteristics. By using a frequency sweep with in-phase and out-of-phase decreasing displacements to the tires, the vehicle sprung and unsprung mass responses can be measured to quantify vertical accelerations across a frequency range. With these data, the resonant frequency characteristics of the front and rear suspensions can be determined. In addition, the acceleration gains of the unsprung mass and the vehicle body can be calculated. This evaluation is effective in identifying the similarities and differences in suspension response among various vehicles and in quantifying the changes of the response to various types of suspension tuning.

Reconstruction of motor vehicle collision crashes typically involves calculation of the change in velocity (Delta-V) of the crash-involved vehicle(s). Many scientific methodologies have been developed for such calculation and many of these require quantification of the damage sustained by the crash-involved vehicle(s) as a first step in that Delta-V calculation. Occasionally, this methodology is complicated when one or more of the crash vehicle(s) has been repaired or destroyed before the crush can be directly measured during a “hands on” physical inspection. In many instances, the only available documentation of the post-crash vehicle damage is a handful of photographs and/or videotape footage. The methodology detailed in this paper evaluates the accuracy and reliability of three-dimensional wireframe modeling techniques based on two-dimensional photographs to quantify the vehicle crush.

In this study, tests were performed to understand the effects of asymmetric longitudinal forces on vehicle response which may be created in certain staged partial tire tread belt detachment tests. In a very small number of tests performed by others, tires cut to simulate partial tire tread belt detachments created longitudinal drag forces at the separating tire that induced substantial vehicle yaw. This drag force and yaw response are independent of vehicle type and suspension type; they are created by the separating tire tread interacting with the road surface and / or vehicle. Similar yaw inducing drag forces are further demonstrated by applying braking to only the right rear wheel location of an instrumented test vehicle. It is shown that vehicle yaw response results from this longitudinal force as opposed to vertical axle motion.

In this study, tests were performed with modified tires at the right rear location on a solid axle sport utility vehicle to compare vehicle inputs and responses from both: (1) staged tire tread belt detachments, and (2) stepped diameter (“lumpy”) tires. Lumpy tires consist of equal size sections of tread that are vulcanized at equidistant locations around the outer circumference of the tire casing. Some have used lumpy tires in attempt to model the force and displacement inputs created by a tire tread belt separation. Four configurations were evaluated for the lumpy tires: 1-Lump, 2-Lump (2 lengths), and 3-Lump.

Designers of motor vehicles must consider driver and environmental factors to assure that vehicle capacities will be compatible with the likely demands of both to achieve a reasonable degree of safety. Extensive related data are available as a result of a large scale study performed by The National Highway Traffic Safety Administration entitled “Light Vehicle Antilock Brake Systems Research Program”. Mazzae, et al [1] have published a report that described the nature of the program and its general results. Large bodies of data were created that provide further insight into motor vehicle driver behavior in crash avoidance situations. The data quantify driver behaviors in the use of steering and braking controls and of the test vehicle response to these control demands. The current work provides an analysis of these data for consideration by motor vehicle designers and others.

The causes, conditions and circumstances of axle shaft failures are analyzed for use in reconstructing a variety of crashes. A literature search was performed to determine the frequency and the role of vehicle defects, such as axle shaft failures, to crash causation. Real world case studies of axle shaft failures are presented. Static testing force levels required to fracture axle shafts are compared to lateral forces encountered under normal and crash avoidance driving conditions. Vehicle and roadway physical evidence is presented when axle shafts are caused to “fracture” under dynamic testing. Results of the dynamic testing are compared to real world case studies.