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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 this case a Bayesian cross-validation can be carried out by (1) using one measurement and Bayes theorem to compute a posterior distribution for the impact speed, (2) using this posterior distribution to compute a predictive distribution for the second measurement, and then (3) comparing the actual second measurement to this predictive distribution. An actual measurement falling in an extreme tail of the predictive distribution suggests a weakness in the assumptions governing the reconstruction.
Technical Paper

A Comparison Study between PC-Crash Simulation and Instrumented Handling Maneuvers

2011-04-12
2011-01-1121
Lateral acceleration, roll angle, roll rate, and yaw rate vehicle response from PC-Crash were compared to the MSAI sensor data. The authors modeled 26 handling tests. PC-Crash appeared to be a reasonable tool for modeling gross vehicle response. ...This research compares vehicle dynamic simulations in PC-Crash 8.2 to data recorded during instrumented handling tests conducted by Mechanical Systems Analysis Incorporated (MSAI). ...Vehicle weight, center of gravity (c.g) position, suspension stiffness parameters, tire parameters, steering angle, and vehicle speed data provided by MSAI were used as input for the PC-Crash model. Lateral acceleration, roll angle, roll rate, and yaw rate vehicle response from PC-Crash were compared to the MSAI sensor data.
Technical Paper

A New Approach to Occupant Simulation Through the Coupling of PC-Crash and MADYMO

1999-03-01
1999-01-0444
During recent years the accident simulation program PC-Crash was developed. This software simulates vehicle movement before, during and after the impact, using 3D vehicle and scene models. ...A new interface has been developed between MADYMO® and PC-Crash so that, after the reconstruction of an accident, only a few additional parameters regarding restraint system, seat and occupant must be defined. ...A new interface has been developed between MADYMO® and PC-Crash so that, after the reconstruction of an accident, only a few additional parameters regarding restraint system, seat and occupant must be defined. PC-Crash then creates all necessary input files for MADYMO® and starts the occupant simulation.
Technical Paper

A Pilot Study at National Highway-8 for On-Site Crash Data Collection and In-Depth Investigation in India

2017-01-10
2017-26-0001
The importance of on-site, in-depth accident research studies has been recognized internationally especially in developed countries. In order to address problems related to road safety, it is important to understand the epidemiology and causation of crashes. For this an in-depth investigation of the crash site, vehicles involved and injury details is required. Detailed crash information helps in analysing the events leading to crash and developing safety measures and/or intervention to reduce crashes. In order to pilot such an activity in India, an in-depth accident data collection activity had been carried out on national highway connecting Delhi to Jaipur (NH-8) for a duration of over a year by a joint team of IIT-Delhi and NATRiP. A total of 1220 road traffic accidents (RTA) notifications were received by the team, of which 186 cases were attended and detailed data was collected in a pre-decided format.
Technical Paper

A Study on Head Injury Risk in Car-to-Pedestrian Collisions Using FE-Model

2009-06-09
2009-01-2263
Head injury is quite frequently occurred in car-to-pedestrian collisions, which often places an enormous burden to victims and society. To address head protection and understand the head injury mechanisms, in-depth accident investigation and accident reconstructions were conducted. A total of 6 passenger-cars to adult-pedestrian accidents were sampled from the in-depth accident investigation in Changsha China. Accidents were firstly reconstructed by using Multi-bodies (MBS) pedestrian and car models. The head impact conditions such as head impact velocity; position and orientation were calculated from MBS reconstructions, which were then employed to set the initial conditions in the simulation of a head model striking a windshield using Finite Element (FE) head and windshield models. The intracranial pressure and stress distribution of the FE head model were calculated and correlated with the injury outcomes.
Technical Paper

ASSESSMENT OF THE USE OF SEAT BELTS IN BUSES BASED ON RECENT ROAD TRAFFIC ACCIDENTS IN SPAIN

2001-06-04
2001-06-0019
The most important topic in the field of passive safety of buses and coaches nowadays is the future compulsory use of seat belts. The objective of the study performed by IDIADA AUTOMOTIVE TECHNOLOGY SA and CENTRO ZARAGOZA is to make an important contribution to the existing technical data about this subject. This paper is based on the in-depth analysis of recent road traffic accidents where buses were involved. The first step is the accident reconstruction. A complete injury report including description and causes of occupant injuries is the basis for the correlation of a computer simulation model. Experience in the development of coach seats equipped with seat belts enables the preparation of a comparative model. The hypothesis that the consequences of the accident could have been less severe if the occupants of the bus had worn a seat belt can be evaluated. The conclusions will help the legislators make the right decision.
Technical Paper

An Analytical Review and Extension of Two Decades of Research Related to PC-Crash Simulation Software

2018-04-03
2018-01-0523
PC-Crash is a vehicular accident simulation software that is widely used by the accident reconstruction community. ...The goal of this article is to review the prior literature that has addressed the capabilities of PC-Crash and its accuracy and reliability for various applications (planar collisions, rollovers, and human motion). ...In addition, this article aims to add additional analysis of the capabilities of PC-Crash for simulating planar collisions and rollovers. Simulation analysis of five planar collisions originally reported and analyzed by Bailey [2000] are reexamined.
Technical Paper

Analysis of Finite Element Models for Head Injury Investigation: Reconstruction of Four Real-World Impacts

2005-11-09
2005-22-0001
Previous studies have shown that both excessive linear and rotational accelerations are the cause of head injuries. Although the head injury criterion has been beneficial as an indicator of head injury risk, it only considers linear acceleration, so there is a need to consider both types of motion in future safety standards. Advanced models of the head/brain complex have recently been developed to gain a better understanding of head injury biomechanics. While these models have been verified against laboratory experimental data, there is a lack of suitable real-world data available for validation. Hence, using two computer models of the head/brain, the objective of the current study was to reconstruct four real-world crashes with known head injury outcomes in a full-vehicle crash laboratory, simulate head/brain responses using kinematics obtained during these reconstructions, and to compare the results predicted by the models against the actual injuries sustained by the occupant.
Technical Paper

Analysis of a Dolly Rollover with PC-Crash

2009-04-20
2009-01-0822
The current capabilities of PC-Crash for rollover modeling are discussed and suggestions are made for how PC-Crash might be improved for modeling rollovers. ...This paper evaluates the use of PC-Crash simulation software for modeling the dynamics of a dolly rollover crash test. The specific test used for this research utilized a Ford sport utility vehicle and was run in accordance with SAE J2114. ...Next, the test was modeled using PC-Crash. The simulation was optimized to yield a reasonable fit with the actual test dynamics by changing the following parameters in PC-Crash: (1) the friction coefficient associated with each vehicle-to-ground impact; (2) the coefficient of restitution for vehicle-to-ground impacts; (3) the vehicle body stiffness; and (4) the vehicle suspension and damping.
Technical Paper

Application of the Monte Carlo Methods for Stability Analysis within the Accident Reconstruction Software PC-CRASH

2003-03-03
2003-01-0488
During recent years the accident simulation program PC-CRASH was developed, which allows simulating the vehicles movement before, during and after the impact. ...The first one serves as an alternative for the optimizer tool and is included in the current version of PC-Crash. It gives reasonable insight in the variation of certain parameters in reasonable calculation time.
Technical Paper

Bayesian Uncertainty Quantification for Planar Impact Crashes via Markov Chain Monte Carlo Simulation

2016-04-05
2016-01-1481
A continuing topic of interest is how to best use information from Event Data Recorders (EDR) to reconstruct crashes. If one has a model which can predict EDR data from values of the target variables of interest, such as vehicle speeds at impact, then in principle one can invert this model to estimate the target values from EDR measurements. In practice though this can require solving a system of nonlinear equations and a reasonably flexible method for carrying this out involves replacing the inverse problem with nonlinear least-squares (NLS) minimization. NLS has been successfully applied to two-vehicle planar impact crashes in order to estimate impact speeds from different combinations of EDR, crush, and exit angle measurements, but an open question is how to assess the uncertainty associated with these estimates. This paper describes how Markov Chain Monte Carlo (MCMC) simulation can be used to quantify uncertainty in planar impact crashes.
Technical Paper

Challenges in Simulation and Sensor Development for Occupant Protection in Rollover Accidents

2000-11-01
2000-01-C038
Automotive occupant safety continues to evolve. At present this area has gathered a strong consumer interest which the vehicle manufacturers are tapping into with the introduction of many new safety technologies. Initially, individual passive devices and features such as seatbelts, knee- bolsters, structural crush zones, airbags etc., were developed for to help save lives and minimize injuries in accidents. Over the years, preventive measures such as improving visibility, headlights, windshield wipers, tire traction etc., were deployed to help reduce the probability of getting into an accident. With tremendous new research and improvements in electronics, we are at the stage of helping to actively avoid accidents in certain situations as well as providing increased protection to vehicle occupants and pedestrians.
Technical Paper

Comparisons of Devices for Measuring Acceleration vs. Time in Braking Tests

2008-04-14
2008-01-0180
The coefficient of friction between a vehicle's tires and the roadway is a key parameter in any accident reconstruction. With the proliferation of vehicle dynamics software, it is often important to have more details regarding the tires interaction with the road than simply the average deceleration rate. Devices which can provide the peak friction as the braking develops, along with the average deceleration during the fully developed sliding phase, are necessary. There are now products widely available to the accident reconstruction market which provides these parameters as well as detailed acceleration vs. time curves. The following products capable of providing these results were tested: Accelerex, Vericom VC3000, and two general purpose accelerometers made by Silicon Designs and Dimension Engineering. Tests were conducted on wet and dry asphalt surfaces using a variety of passenger vehicles and transit buses which confirmed the agreement between these devices.
Technical Paper

Computer Simulation of Steer-Induced Rollover Events Via SIMON

2011-04-12
2011-01-1122
This study examines through computer simulation the reconstruction of on-road vehicle rollover accidents induced by a driver steering maneuver. The three-dimensional vehicle dynamics software package SIMON is used to model a set of four test vehicles as six degree-of-freedom sprung masses with up to five degrees-of-freedom for each unsprung mass. The performance of the simulator's physics model, in the context of accident reconstruction, is evaluated through correlation with full-scale vehicle rollover tests. Of specific interest to this study was simulation of the trip phase of the vehicle's motion. The correlation parameters include vehicle trajectory, speed, heading angle, yaw rate, roll angle, roll rate and lateral acceleration. SIMON's capacity to accurately model the physics of a test vehicle's suspension and tire kinetics in the pre-trip and trip phases of motion is evaluated by modeling a set of four instrumented full-scale tests of steering-induced rollovers.
Technical Paper

Development of CAE Methodology for Rollover Sensing Algorithm

2009-04-20
2009-01-0828
The Rollover CAE model is developed for Rollover sensing algorithm in this paper. By using suggested CAE model, it is possible to make sensing data of rollover test matrix and these data can be used for calibration of rollover sensing algorithm. Developed vehicle model consists of three parts: a vehicle parts, an occupant parts and a ground boundary conditions. The vehicle parts include detailed suspension model and FE structure model. The occupant parts include ATD (anthropomorphic test device) male dummy and restraint systems: Curtain Airbag and Seat-Belt. We find analytical value of the suspension model through correlation with vehicle drop test, simulate this model under the conditions of untripped (Embankment, Corkscrew) and tripped (Curb-Trip, Soil-Trip) rollover scenarios. Comparison of the simulation and experimental data shows that the simulation results of suggested CAE model can be substituted for the experimental ones in calibration of rollover sensing algorithm.
Technical Paper

Driver Perception of Lateral Collision Threats

2020-04-14
2020-01-1198
Immediate collision hazards pose obvious threats to approaching drivers and therefore provoke emergency evasive responses. When the hazard is a vehicle intruding into the lane ahead, how its movement characteristics influence an approaching driver’s response is not well understood. This study examined the relationship between intruding vehicle motion and hazard perception. Seventeen subjects viewed first-person perspective recordings of a simulated vehicle travelling down a two-lane roadway containing several intersections with stop-controlled minor roads. Stopped vehicles were located at approximately half of the minor road intersections. Throughout the study, some vehicles (termed ‘intruders’) accelerated into the subject’s lane of travel at 1 of 6 pre-determined acceleration rates. Subjects were instructed to ‘brake’ their vehicle by pressing the space bar on a keyboard as soon as they perceived that a collision was imminent.
Technical Paper

EVALUATION OF THE EFFECTIVENESS OF PEDESTRIAN PROTECTION SYSTEMS THROUGH IN-DEPTH ACCIDENT INVESTIGATION, RECONSTRUCTION AND SIMULATION

2009-10-06
2009-36-0398
All of them are analysed in-depth and reconstructed with PC-Crash. The effects of the frontal structure of the vehicles and several active systems, such as BAS and Pedestrian Detection Systems, are evaluated. ...The paper includes the description of the methodology followed for a sample of approximately 140 pedestrian urban accidents in three cities in Spain (Madrid, Barcelona and Zaragoza) and the corresponding reconstructions done with PC-Crash. Then, a methodology to simulate the passive and active improvements (including pedestrian friendly structure, BAS and pedestrian detection system) is defined and applied to all the sampled accidents.
Technical Paper

Effective Numerical Simulation Tool for Real-World Rollover Accidents by Combining PC-Crash and FEA

2007-04-16
2007-01-1773
In this work, we focused on the trip-over type, which occurs most frequently, and performed simulations to reproduce real-world rollover accidents by combining PC-Crash and FEA. At first, using a simplified full car model, sufficient conditions, such as additional velocity, required for a curb trip-over accident to occur, were derived from energy balance concept based on the same principle as critical sliding velocity (CSV) criterion. ...Based on rigid body dynamics, PC-Crash software was chosen to make an accident reconstruction analysis of some selected cases chosen from an accident database (NASS-CDS). ...The output of this PC-crash simulation was then used as the initial input conditions (i.e., speed, deceleration, etc.) of a detailed finite element analysis.
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