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Brake vacuum booster characteristics are of great importance to understanding overall brake system operation in light vehicles so equipped. In recent years, engineering reports relevant to traffic crash reconstruction have discussed, among related areas, the operation of brake booster systems at high applied brake pedal force levels and with various levels of vacuum available within the booster. A vehicle-testing framework is presented for characterizing and understanding the operation of a vacuum booster with pedal force ranging above the vacuum runout point, as well as booster operation relative to varying levels of available vacuum and patterns of depletion of stored vacuum. Concepts are illustrated with measurements of exemplar vehicles. The objective of this paper is to promote improved understanding of brake booster operation and to advance more precise articulation of related concepts within the crash reconstruction community.

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.

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.

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.

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.