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Technical Paper

The Trailer Simulation Model of PC-CRASH

The program PC-CRASH was developed for the reconstruction of vehicle accidents and considers pre-impact, collision and post-impact phases. ...The present paper describes the physical and mathematical model which was added recently to PC-CRASH in order to enable the simulation of the dynamic behavior of articulated vehicles (with both single and double axle semi-trailers and with steered trailers).
Technical Paper

Validation of a PC-Crash Multibody Sport Bike Motorcycle Model

PC-Crash is an accident reconstruction program allowing the user to perform simulations with multibody objects that collide or interact with 3D vehicle mesh models. ...The current motorcycle models in PC-Crash are generic and do not resemble a sport bike type motorcycle. They are only globally scalable such that you cannot adjust length, width, or height independently. ...The test results were compared to parameters calculated in PC-Crash. Results such as Delta-V, yaw rate and overall post impact trajectories of the motorcycle, rider and movement of the target vehicle were compared to the data from the instrumented test vehicles.
Technical Paper

The Measured Rolling Resistance of Vehicles for Accident Reconstruction

Knowledge about vehicle rolling resistance is required to calculate speed loss of accident vehicles during portions of their pre-impact and post-impact trajectory when they are not braking or sliding directly sideways. The accuracy of assumed rolling resistance values is most important in accidents with long post-impact roll out distances. Very little hard data are currently available1 and the accident reconstructionist must usually make estimates of drivetrain losses and normal and damaged tire rolling resistance to determine overall vehicle rolling resistance. In the first part of this study, the rolling resistances of various vehicles with different drive configurations are determined, based on accurate measurements made with a 5th wheel. In the second part, sensitivity analyses are done with PC-Crash2, a computer simulation program, to determine what effect the error in assumed rolling resistance has on speed calculations for various types of post-impact trajectories.
Technical Paper

Measuring and Modeling Suspensions of Passenger Vehicles

Numerical parameters describing suspension stiffness and damping are required for 3D simulation of vehicle trajectories, but may not be available. This paper outlines a simple, portable method of measuring these properties with a coefficient of variation of 5% on stiffness. 24 of 26 vehicles tested were significantly stiffer in roll than pitch, complicating analyses with models that don't include anti-roll. Suspension parameters did not correlate with static wheel load distribution, and damping coefficient did not correlate with natural frequency. Computer simulations of the speed required to initiate rollover in an S-curve were highly sensitive to the suspension parameters used. When pre-impact tire marks and rollover distance were considered, the simulations became almost insensitive to suspension parameters.
Technical Paper

Yaw Testing of an Instrumented Vehicle with and without Braking

Two methods for calculating speed from curved tire marks were investigated. The commonly used critical speed formula and a computer simulation program were evaluated based on their ability to reproduce the results of full-scale yaw tests. The effects of vehicle braking and friction coefficient were studied. Twenty-two yaw tests were conducted at speeds between 70 and 120 km/h. For half of the tests, about 30% braking was applied. Using the measured sliding coefficient of friction, both the critical speed formula and the computer simulations under-predicted the actual speed of the vehicle. Using the measured peak coefficient of friction, both methods over-estimated the actual speed. There was less variance in the computer simulation results. Braking tended to increase the speeds calculated by the critical speed formula.
Technical Paper

Mobility in mining: Issues for road safety improvement

The increase of mining activities in the northern regions of Chile has brought about a new environment in terms of mobility to those areas where this industry has moved forward. This change has not only affected road traffic accidents on public roads of the surrounding mines, but also the inner organization of the mining companies, which must fulfill strict regulations, achieving the highest levels of safety. Given this situation, the current road traffic accidentology with respect to the northern regions of Chile has been analyzed in this paper. The results of the analysis have shown the relevant weight of the human factor and the state of the infrastructure related to the number of road fatalities. Thus, this paper provides solutions to combine the existing driver-centered technologies together with GPS systems that can track the movement of several vehicles and the design of safety berms in mine haul roads to mitigate the number of fatalities associated with mining activity.
Technical Paper


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

Evaluation of the Effectiveness of Volvo’s Pedestrian Detection System Based on Selected Real-Life Fatal Pedestrian Accidents

The objective of this work is to test the potential benefit of active pedestrian protection systems. The tests are based on real fatal accidents with passenger cars that were not equipped with active safety systems. Tests have been conducted in order to evaluate what the real benefit of the active safety system would be, and not to gain only a methodological prediction. The testing procedure was the first independent testing in the world which was based on real fatal pedestrian accidents. The aim of the tests is to evaluate the effectiveness of the Volvo pedestrian detection system. The in-depth accident database ZEDATU contains about 300 fatal pedestrian traffic accidents in urban areas. Eighteen cases of pedestrians hit by the front end of a passenger vehicle were extracted from this database. Cases covering an average traffic scenario have been reconstructed to obtain detailed model situations for testing.
Technical Paper

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

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

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

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

Accuracy and Sensitivity of Yaw Speed Analysis to Available Data

Accident reconstructionists rarely have complete data with which to determine vehicle speed, and so the true value must be bracketed within a range. Previous work has shown the effect of friction uncertainty in determining speed from tire marks left by a vehicle in yaw. The goal of the current study was to assess improvements in the accuracy of vehicle speed estimated from yaw marks using progressively more scene and vehicle information. Data for this analysis came from staged S-turn maneuvers that in some cases led to rollover of sport utility vehicles. Initial speeds were first calculated using the critical curve speed (CCS) formula on the yaw marks from the first portion of the S-maneuver. Then computer simulations were performed with progressively more input data: i) the complete tire marks from the whole S-maneuver, ii) measured vehicle mass, iii) measured suspension stiffness and damping, and iv) measured steering history.
Technical Paper

Empirical Testing of Vehicular Rotational Motion

Vehicles often rotate during traffic collisions due to impact forces or excessive steering maneuvers. In analyzing these situations, accident reconstructionists need to apply accurate deceleration rates for vehicles that are both rotating and translating to a final resting position. Determining a proper rate of deceleration is a challenging but critical step in calculating energy or momentum-based solutions for analytical purposes. In this research, multiple empirical tests were performed using an instrumented vehicle that was subjected to induced rotational maneuvers. A Ford Crown Victoria passenger car was equipped with a modified brake system where selected wheels could be isolated. The tests were performed on a dry asphalt surface at speeds of approximately 50 mph. In each of the tests, the vehicle rotated approximately 180 degrees with the wheels on one side being completely locked.
Technical Paper

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

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

RICSAC-97 A Reevaluation of the Reference Set of Full Scale Crash Tests

Research performed in the 1970's revealed significant limitations in the available documentation of vehicle crush information and trajectory spinout information. As a result a series of full-scale crash tests were performed which became known as the Research Input for Computer Simulation of Automobile Collisions (RICSAC) crash tests. Previous research using the RICSAC test results, particularly in relation to the validation of accident reconstruction computer programs, has varied widely in acceptance, interpretation and presentation of the RICSAC test results. This paper presents a detailed review and decipherment in useable form of the original 12 crash tests that were performed within the RICSAC program. A new method of analyzing accelerometer data from arbitrary sensor positions, on the basis of discrete measures of the vehicle responses rather than complete time-histories, is defined.
Technical Paper

Computer Simulation of Steer-Induced Rollover Events Via SIMON

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

An Investigation into C-NCAP AEB System Assessment Protocol

In order to speed up the development of vehicle active safety technology in China, C-NCAP plans to add AEB and AEB VRU system as assessment items in 2018. With the purpose of studying the assessment protocol of AEB system, we have carried out 400,000 km road information collection and then we acquired the statistics of the operation conditions of dangerous situations. Combined with the traffic accident data collected by CIDAS, we found that the dangerous situations that we usually met were mainly three types, that was CCRs, CCRm and CCRb. Based on what we mentioned above, we analyzed the three kinds of working conditions and gave the corresponding evaluation method. In addition, combined with the actual situation of China, we added two tests of error function. And then we took the actual road experiment of many models of vehicles.
Technical Paper

Driver Perception of Lateral Collision Threats

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.