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Technical Paper

Automated Accident Reconstruction

The Simulation Model of Automobile Collisions (SMAC) computer program was developed by Calspan Corporation as an aid with which to accurately reconstruct road accidents. Part of the overall objective of the research has been to make the system “user oriented” so that users without an engineering background can operate it with ease. ...This has necessitated developing a START program which automatically runs the SMAC program from a minimum of input data and an iteration routine designed to optimize the input values of velocities to provide a “best fit” reconstruction to the available scene data. A summary of how the START program works is given; however, emphasis is placed in the paper on the development of the iterative routine. ...For each example the results of each successive iteration are given to illustrate the manner in which the program converges to an acceptable reconstruction. This paper is based on research performed under Contract No. DOT-HS-5-01124 with the National Highway Traffic Safety Administration.
Technical Paper

Results of Selected Applications to Actual Highway Accidents of SMAC Reconstruction Program

This paper reports the application of the Simulation Model of Automobile Collisions (SMAC) computer program to selected cases of actual highway accidents. Since SMAC was developed to allow accidents to be accurately reconstructed by operators without a detailed knowledge of engineering mechanics, recent developments have concentrated on providing a Start routine. ...Particular emphasis is given to those types of accident that are subject to large errors when reconstructed by the more standard analytical procedures; for example, intersection accidents and accidents involving large spinout trajectories....This program automatically generates the inputs required for SMAC, including collision speed estimates, from a minimum amount of information available at the accident scene. A brief summary of how Start works is given, followed by a discussion of actual cases.
Technical Paper

Techniques for the Reconstruction of Rollover Accidents Involving Sport Utility Vehicles, Light Trucks and Minivans

Finally, techniques are presented which enable the speed of the vehicle at rollover to be calculated and the pre-rollover trajectory to be analyzed. Reconstruction of a number of actual rollover accidents are provided to illustrate the techniques. ...Rollover Accidents account for almost 50 percent of fatalities that occur in sport utility vehicles, pickups and minivans, such that increased attention is being paid to these types of accidents. ...Rollover Accidents account for almost 50 percent of fatalities that occur in sport utility vehicles, pickups and minivans, such that increased attention is being paid to these types of accidents. This paper discusses the common types of situations that lead to vehicle rollover of multipurpose passenger vehicles, and the mechanisms that precipitate these situations.
Technical Paper

The Role of Vehicle Handling in Accident Causation

This paper reports the results of a study designed to investigate the relation between vehicle handling and accident frequency. Because evaluation of the driver control process can only be made on a subjective basis, emphasis is placed on evaluating the role of the vehicle rather than the man-car combination. ...Deficiencies in handling are likely to be associated with accidents involving loss of control, and it is shown that over 80 percent of loss of control accidents involve single vehicles only. ...This means that the single vehicle accident rate can be used as a measure of proneness of loss of control. Single vehicle accident rates are determined by model of car and the effect on these rates of other factors, such as variations in driver age and ratio of male to female driver population between the different models, are assessed.
Technical Paper

Development and Evaluation of the CRASH 2 Program for Use under European Conditions

This paper reports recent work undertaken by the Oxford Road Accident Group to improve the utility of the CRASH 2 (Calspan Reconstruction of Accident Speeds on the Highway) program. ...Although CRASH 2 is being used extensively in the U.S.A. for accident reconstruction, its use in Europe is limited. The accident environment in Europe is sufficiently different from that in the United States that it has been suggested that the program could be of limited use under these conditions. ...Accordingly, to provide reliable figures as to the utility of the program under European conditions a representative sample of accidents has been reconstructed using CRASH 2: the sample consisted of 200 accidents investigated on-scene and 200 accidents investigated on a 48 hour follow-up basis.
Technical Paper

Further Validation of the Simulation Model of Automobile Collisions Program

A variety of impact configurations were run including: 60° front-to-side, 90° front-to-side, 10° offset head-on and 10° offset rear-end. The reconstruction of each test is discussed and compared with the measured data, using the final rest positions, velocity changes, and damage profiles of each vehicle.
Technical Paper

Engineering Parameters Related to Rollover Frequency

Logistic regression techniques were used to develop parameter estimates for the risk of rollover in single vehicle fatal crashes. Fatal Accident Reporting System (FARS) data for 1981-1 987 were used together with engineering data for 11 models of pickup, 16 models of utility vehicle and 11 models of passenger car.
Technical Paper

The Mechanics of Rollover as the Result of Curb Impact

This paper analyses the mechanics of overturning which occurs as the result of a vehicle colliding with a curb or similar obstacle. Because the duration of impact is short, the forces involved may be treated as impulsive forces and a graphical method may be used to determine the terminal velocities after the impact. The mathematical analysis is supported by results obtained from a film of an actual track test in which rollover was induced by sliding a car sideways into a curb. The motion of the vehicle after impact with the curb was also analysed in this film. During airborne motion, the car may be considered as a simple projectile and any aerodynamic effects neglected.
Technical Paper

The Effects of Restraint Use and Mass in “Downsized” Cars

This paper examines the effects that downsizing has had on occupant injury. Statistical models are derived which demonstrate the relative risks associated with downsized cars and restraint use. Then actual occupant injuries are analysed to show how the total pattern of occupant injuries changes with downsizing. Each additional thousand pounds of vehicle mass decreases the odds of a driver injury in a crash by 34 percent when the driver is not restrained. For restrained drivers, this decrease is 25 percent per thousand. Restraint use further decreases the odds of a driver injury by two-thirds. To gain the same reduction in injury odds afforded the belted driver of a 2500 pound passenger car, the unbelted driver requires a 4325 pound car. For unrestrained occupants, the instrument panel, steering assembly and windshield (in frontal impacts) are the most frequent sources of injury.