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Technical Paper

The Vocabulary of Accident Reconstruction

Nevertheless, accident reconstructionists measure the degree of severity of vehicular accidents by calculating terms that are called Collision Parameters. ...The principal objective of this paper is to describe the significance of the Collision Parameters and explain the vocabulary of accident reconstruction. A non-mathematical approach is utilized to provide a thorough understanding for the general public. ...Vehicular accidents occur in everyday life. Their degree of severity is often perceived by the general public based on the amount of human bodily injuries sustained.
Technical Paper

Application of Force Balance Method in Accident Reconstruction

In the field of accident reconstruction, there has been a significant amount of effort devoted to the calculation and derivation of vehicle crush energy and vehicle stiffness. ...This ultimately increases the accuracy of the overall accident reconstruction. In this paper, examples will be given to illustrate the use of such a methodology. ...But, oftentimes, crush profiles and/or crush stiffnesses are not available and accident constructionists face the situation of insufficient information. In some such cases, the force balance method can be used to reduce the uncertainty.
Technical Paper

Spot Weld Failure Analysis for Accident Reconstruction

Adequacy of resistance spot welds in low carbon steels in relation to structural integrity can become an issue in the reconstruction of automotive accidents. Because formation of a plug (or button or slug) in a peel test is used as a quality control criterion for welds, it is sometimes assumed conversely that a weld which failed is defective if no plug is present.
Technical Paper

Perception/Reaction Time Values for Accident Reconstruction

Field literature in testing and experimentation on general human perception and reaction times, was reviewed to better address questions on the parameters of driving performance. Brake reaction time studies and driver visual search studies were reviewed with attendant material on the effects of aging, intoxication and fatigue. A short examination is made on the degree of increase in “surprise intrusion” event upper values from simple human basic reaction time testing to a real-time pedestrian crossing event in real-world urban driving. These upper range values began at 0.78 second in the laboratory environment and became 2.50 seconds on an urban street in real-time.
Technical Paper

An Overview of the Evolution of Computer Assisted Motor Vehicle Accident Reconstruction

In addition, a brief computer development history is discussed to demonstrate how the evolution of computer assisted vehicle accident reconstruction becomes feasible for a reconstructionist. Possible future research in computer reconstruction is also discussed. ...This paper presents an overview of the evolution of computer simulations in vehicle collision and occupant kinematic reconstructions. The basic principles behind these simulations, the origin of these programs and the evolution of these programs from a basic analytical mathematical model to a sophisticated computer program are discussed. ...Possible future research in computer reconstruction is also discussed.
Journal Article

Application of Air Brake Performance Relationships in Accident Reconstruction and Their Correlation to Real Vehicle Performance

This research paper builds onto the wealth of technical information that has been published in the past by engineers such as Flick, Radlinski, and Heusser. For this paper, the pushrod force versus chamber pressure data published by Heusser are supplemented with data taken from brake chamber types not reported on by Heusser in 1991. The utility of Heusser's braking force relationships is explored and discussed. Finally, a straightforward and robust method for calculating truck braking performance, based on the brake stroke measurements and published heavy truck braking test results, is introduced and compared to full-scale vehicle test data.
Technical Paper

Reconstruction of Real World Pedestrian Impact

The physical reconstruction results are then compared to the actual accident damage and conclusions are rendered. ...This paper presents a pedestrian head impact reconstruction methodology as an initial mitigating response to this need for pedestrian protection. ...This methodology which is based on preliminary testing results is illustrated with a real world case example from the Pedestrian Accident Investigation Data Support (PAIDS) Study. This PAIDS study provides documentation of medical reports, vehicle impact speeds, photographs and a dent profile of the vehicle damage.
Technical Paper

Animated Reconstruction of Automobile Collisions Using SMAC

Accident reconstruction encompasses the evaluation of a crash situation from evidence and observations available after the accident. ...Accident reconstruction encompasses the evaluation of a crash situation from evidence and observations available after the accident. Such evidence includes vehicular damage, property damage, marks, and witness statements. ...The reconstructionist is responsible for transforming this information into a theory of the accident sequence. In addition to satisfying the evidence and statements, the theory must also agree with the laws of physics which dictate reactions to forces and torques.
Technical Paper

Computer Accident Simulation - Pretty Pictures and the Real World

Examples of various cases are presented to illustrate the engineer's accident reconstruction and how the reconstruction is used to establish the computer simulation. ...A Computer Accident Simulation (CAS) is the application of dynamics to known physical evidence to yield a best approximation of the interactions of vehicles and other objects during the real world accident scenario. The simulation is based upon the reconstruction after an engineer's examination of the vehicles involved, the roadway (i.e., skid marks and gouges), and any substantiated evidence from witnesses. ...A Computer Accident Simulation (CAS) is the application of dynamics to known physical evidence to yield a best approximation of the interactions of vehicles and other objects during the real world accident scenario.
Technical Paper

Head Impact Reconstruction - HIC Validation and Pedestrian Injury Risk

Experimental reconstructions of pedestrian accidents involving head injury sustained primarily from hood impact were conducted to determine the relationship between HIC and injury severity. ...Results of the two analyses were compared to determine the degree of agreement between the HIC/injury-risk relationship derived from controlled experiments with cadavers and that derived from uncontrolled accidents involving live people. The reconstruction test results also were used to derive a relationship between head injury risk (HIC) and vehicle impact speed. ...Specific accident cases are cited to illustrate the use of this relationship by the accident reconstructionist in estimating probable vehicle speed from injury outcome.
Technical Paper

A Demographic Analysis and Reconstruction of Selected Cases from the Pedestrian Crash Data Study

The first is the finalization of the Pedestrian Crash Data Study (PCDS) in order to provide detailed information regarding the vehicle/pedestrian accident environment and how it has changed from the interim PCDS information. The pedestrian kinematics, injury contact sources, and injuries were analyzed relative to vehicle geometry. ...The second area presented is full-scale attempts at reconstruction of two selected PCDS cases using the Polar II pedestrian dummy to determine if the pre-crash motion of the pedestrian and vehicle could somehow be linked to the injuries and vehicle damage documented in the case.
Technical Paper

Vehicle and Occupant Response in Heavy Truck to Passenger Car Sideswipe Impacts

This has been an important issue in the field of accident analysis and reconstruction because of the frequency with which the accidents occur and the costs of injuries allegedly associated with them. ...Second, typical accident reconstruction programs are not well suited to accurately determine the vehicle speed changes and accelerations resulting from impacts where the line of the impact force lies far from the vehicle center of gravity, and is influenced by specific features of vehicle geometry. ...The tests were performed to duplicate a real world accident that resulted in litigation. The acceleration near the car’s center of gravity is measured, as is the acceleration of the head of an adult male human volunteer.
Technical Paper

A Comparison Study of Skid and Yaw Marks

The discernment of whether a tire mark on a roadway is the result of a skidding tire or is the result of the rotation of the vehicle with unlocked wheels is important in vehicular accident reconstruction analysis. Resolution of the tire marks left by a vehicle after skidding and/or yawing on dry asphalt were experimentally studied for their similarities and differences under controlled test conditions. ...This paper analyses the results of this study and shows pictorially the differences for use by the accident reconstructionist. Analytical discussion are also presented that illustrate speed determination as estimated from yaw markings on the roadway.
Technical Paper

The Use of Single Moving Vehicle Testing to Duplicate the Dynamic Vehicle Response From Impacts Between Two Moving Vehicles

The results of a reconstruction of the accident will also be described. Next, simulations of the accident using the EDSMAC vehicle impact model included in the HVE-2D computer program developed by EDC Corporation are presented in which both vehicles are moving, only the struck vehicle is moving, and only the striking vehicle is moving. ...The acceptability of this method of testing is not as obvious for the reconstruction of accidents where the impact is non-central, or the angle of impact is not orthogonal. ...While the pre- and post-impact speeds of the vehicles involved in an accident can not be duplicated using this method, closing speeds, vehicle damage, vehicle speed changes and vehicle accelerations can be duplicated.
Journal Article

Comparison of Heavy Truck Engine Control Unit Hard Stop Data with Higher-Resolution On-Vehicle Data

These data provide useful information to accident reconstruction personnel. In past studies, these data have been analyzed and compared to higher-resolution on-vehicle data for several heavy trucks and several makes of passenger cars. ...The goal of this study was to help accident reconstruction professionals better understand engine ECU “hard stop” data currently available on most commercial vehicles.
Technical Paper

Analysis of Motorcycle Braking Performance and Associated Braking Marks

Further, this paper examines the applicability of drag factors used in accident reconstruction, given the complexity of typical motorcycle braking systems, and the myriad of rider strategies and conditions under which emergency braking maneuvers might occur. ...This paper should also serve to assist the vehicle accident reconstructionist in complementing the existing data on motorcycle braking performance.
Technical Paper

Review of Pedestrian Safety Research in the United States

Pedestrian vehicle accidents account for a considerable proportion of all automobile related injuries and deaths each year. ...The state of pedestrian accident research is also reviewed in the light of national and International interest in reducing pedestrian injuries.