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Journal Article

A Bayesian Approach to Cross-Validation in Pedestrian Accident Reconstruction

2011-04-12
2011-01-0290
In statistical modeling, cross-validation refers to the practice of fitting a model with part of the available data, and then using predictions of the unused data to test and improve the fitted model. In accident reconstruction, cross-validation is possible when two different measurements can be used to estimate the same accident feature, such as when measured skidmark length and pedestrian throw distance each provide an estimate of impact speed. ...In accident reconstruction, cross-validation is possible when two different measurements can be used to estimate the same accident feature, such as when measured skidmark length and pedestrian throw distance each provide an estimate of impact speed. ...An actual measurement falling in an extreme tail of the predictive distribution suggests a weakness in the assumptions governing the reconstruction. This paper describes an implementation of these ideas using the Bayesian freeware WinBUGS.
Technical Paper

Crush Energy in Accident Reconstruction

1986-02-24
860371
Vehicle accident reconstruction methods based on deformation energy are argued to be an increasingly valuable tool to the accident reconstructionist, provided reliable data, reasonable analysis techniques, and sound engineering judgement accompany their use. ...Vehicle accident reconstruction methods based on deformation energy are argued to be an increasingly valuable tool to the accident reconstructionist, provided reliable data, reasonable analysis techniques, and sound engineering judgement accompany their use. ...It is concluded that the deformation energy for an accident vehicle can be estimated using the CRASH model provided that test data specific to the accident vehicle is utilized.
Technical Paper

Night Visibility Video for Accident Reconstruction

1996-02-01
960895
The characteristics, use and adaptability cf the system for a variety of accident reconstruction activities is described....A new low light video recording system is described which can be used to document visibility conditions at nighttime accident scenes. The system includes a means for calibrating the recording and playback equipment for the prevailing illumination conditions while on location at an accident scene. ...The system includes a means for calibrating the recording and playback equipment for the prevailing illumination conditions while on location at an accident scene. Use of a hand-held grey scale chart facilitates calibration of the equipment and provides a visual check during playback.
Technical Paper

Crash Pulse Scaling Applied to Accident Reconstruction

2008-04-14
2008-01-0183
Scaling formulas for time and acceleration are derived based upon commonly available accident reconstruction information from the crush profiles, closing speed, and vehicle deltaV. ...A crash test similar to the accident may not be readily available unless a crash test is performed that is designed to represent a specific accident. Available test results may not reproduce the accident but may approximate it in several important aspects. ...A crash pulse representative of the accident event is often requested in addition to the reconstructed speed, deltaV, and PDOF. One approach to crash pulse generation is to scale available test data to the accident condition.
Technical Paper

Vision and Visibility in Vehicular Accident Reconstruction

1990-02-01
900369
This determination must be made with proper consideration of both inter- and intra-person variability The goal of accident reconstruction is to determine what happened in an accident, and why it happened. This process involves a thorough examination of the available evidence. ...Furthermore, the question of why the accident happened may not be addressed at all by analysis of the physical evidence alone, as almost all accidents are influenced by the performance of the people involved in the accident. Human performance issues such as vision, attention, and distraction, often play a large role in why an accident happens. ...The purpose of this paper is to illustrate the value of considering issues of vision and visibility when reconstructing an accident. Illustrative examples from actual accidents will be used throughout.
Technical Paper

The “IMPAC” Computer Program for Accident Reconstruction

1985-02-25
850254
The computer program “IMPAC” (impact Momentum of a Planar Angled Collision) was developed for use in accident reconstruction to study the impact phase of a collision. It may be used for vehicle to vehicle or vehicle to fixed object impacts.
Technical Paper

Tire-Road Friction in Winter Conditions for Accident Reconstruction

1996-02-01
960657
The paper presents original research and summarizes the published literature regarding tests of tire-road friction in winter conditions. The original research investigated the effect of temperature variation on tire-road friction on a variety of winter driving surfaces, including an investigation of the variation of friction coefficient with the dispersion rate of applied sand. Tests were conducted on surfaces including bare asphalt, black ice, ice and snow, ice and snow with a variety of sand overlays, ice and snow with a layer of fresh snow, and glare ice at temperatures ranging from -42°C to -4°C (-44°F to 25°F). The published literature relating to tests of friction in winter driving conditions was surveyed, and data from the original research and the previous publications is presented in a uniform fashion.
Technical Paper

Impact Center and Restitution Coefficients for Accident Reconstruction

1994-03-01
940564
Based on a previously presented two-dimensional car-to-car impact model, automobile collision tests were analyzed to understand the relationship of the impact center to the residual vehicle deformation, which is essential for improving the reliability of the impact model. The results from a number of automobile collision tests indicated that the impact centers of the two vehicles at the end of collision were located near the center of the contacting surface when the vehicle deformation is maximized. This leads to a method of defining the impact center from the crush profile at the time of maximum deformation. The relationships of the normal and tangential restitution coefficients to the collision type were also presented, discussed and evaluated to obtain some guidelines on how to choose the restitution coefficients from impact conditions.
Technical Paper

Crash Testing with a Massive Moving Barrier as an Accident Reconstruction Tool

2000-03-06
2000-01-0604
Damage analysis methods in accident reconstruction use an estimate of vehicle stiffness together with measured crush to calculate crush energy, closing speed, and vehicle delta-V. ...Massive moving barrier (MMB) testing is introduced as a tool to obtain additional and accident specific stiffness coefficients applicable for reconstruction. The MMB impacts a stationary vehicle of similar structure as the accident vehicle under accident-specific conditions like impact location, angle, over-ride / under-ride, offset and damage energy. ...Stiffness is generally derived from barrier crash test data. The accident being reconstructed often involves one or more conditions for which vehicle stiffness is not well defined by existing crash tests.
Technical Paper

Updating Generic Crush Stiffness Coefficients for Accident Reconstruction

2010-09-30
2010-01-1581
However, this paper, along with Hargens and Day's earlier paper, “Vehicle Data Sources for Accident Reconstruction” [ 3 ], are now somewhat outdated by newer model vehicles. New generic crush stiffness coefficient values were calculated to better represent newer vehicles produced between 1990-1999 and 2000-2009. ...Often, the accident reconstructionist will find that there is no crash test data for a particular vehicle, making a direct calculation of the crush stiffness coefficients impossible without performing an actual crash test.
Technical Paper

Accident Reconstruction Using Data Retrieval from Crash-Test Video Images

2016-04-05
2016-01-1464
The main source for the estimation of stiffness coefficients to be used in accident reconstruction calculations is a very large database of crash-test related information from NHTSA. ...This methodology allowed to extend the existing database of US cars to European models and to significantly improve the calculation of the dissipated energies associated to the permanent damage caused by accidents.
Technical Paper

Data Retrieval by Accident Reconstruction for Safer Vehicle Design

1972-02-01
720284
The effectiveness of safety design must be justified in terms of real automobile accidents with human occupants. Since it is far too dangerous to use human subjects in full-scale collision experiments, substitutes are usually studied, that is, experiments performed with dummies and mathematical models. ...Full-scale collision experiments with human occupants could be performed by reconstructing real automobile accidents accurately. To retrieve the most needed data for further improvements in safety design and to translate actual accidents as controlled experiments, an engineered method was developed to reconstruct accidents. ...To retrieve the most needed data for further improvements in safety design and to translate actual accidents as controlled experiments, an engineered method was developed to reconstruct accidents.
Technical Paper

Use of Throw Distances of Pedestrians and Bicyclists as Part of a Scientific Accident Reconstruction Method

2004-03-08
2004-01-1216
Experts use the following information to calculate speed: Information on final position of vehicles, deformation pattern on vehicles, traces found on the road, such as braking and sliding marks, throw distances of pedestrians and cyclists and injury pattern, all these issues are given possibilities for reconstruction of the movement of the human body. While in car to car crashes the speed calculation is based on the momentum analysis and on energy balance hypothesis of classical physics, the calculation for pedestrian and bicycle accidents have to be based on traces only. ...While in car to car crashes the speed calculation is based on the momentum analysis and on energy balance hypothesis of classical physics, the calculation for pedestrian and bicycle accidents have to be based on traces only. The paper describes the possibilities of the use of throw distance as a reconstruction method. ...The paper describes the possibilities of the use of throw distance as a reconstruction method. The paper also discusses the tolerance fields, compared to the results of crash tests.
Technical Paper

Impact Model for Accident Reconstruction - Normal and Tangential Restitution Coefficients

1993-03-01
930654
Sixteen car-to-car impact tests, including side swipe type collisions, were conducted to obtain primary data for validating the model and improving its reliability in accident analysis. The relationship of the normal and tangential restitution coefficients to the collision type was obtained with a generalized impulse ratio from the analysis of test data by using the impact model. ...This paper presents the formulas used in the model and demonstrates their applications to accident analysis. The following analytical formulas are introduced: The relationship between energy loss and delta-V.
Technical Paper

Reconstruction of Rollover Collisions

1989-02-01
890857
The fundamentals of accident reconstruction are applied to rollover collisions. Typical deceleration rates, roll distances, and vehicle damage patterns are discussed.
Technical Paper

Speedometers and Collision Reconstruction

2017-03-28
2017-01-1412
As part of recent ITAI (Institute of Traffic Accident Investigators) crash test events in the UK, a number of instrument clusters were installed in vehicles to simulate both frontal and side impacts.
Technical Paper

Full-Scale Moving Motorcycle into Moving Car Crash Testing for Use in Safety Design and Accident Reconstruction

2012-04-16
2012-01-0103
Similarly, the published data indicates that historic analyses of motorcycle accidents and the advancements in motorcycle safety designs have been based, in large part, on single-moving-vehicle crash tests. ...For two-moving-vehicle accidents, the rotation of the motorcycle front wheel and the resulting asymmetric compression and deformation of the front forks affects the post-impact motion of the motorcycle rider and the deformation of both the motorcycle and the other vehicle.
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