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Technical Paper

Pycrash: An Open-Source Tool for Accident Reconstruction

2021-04-06
2021-01-0896
In this paper, the current capabilities of Pycrash are illustrated and its accuracy is assessed using matching PC-Crash simulations performed using PC-Crash. The results indicate that Pycrash is well-equipped to perform fundamental accident reconstruction analyses, including impact related effects, but its simplified suspension model is a limitation.
Journal Article

Effects of Situational Urgency on the Perception and Response Time to Lateral Collision Hazards

2021-04-06
2021-01-0857
Situational urgency influences the perception and response time (PRT) interval of drivers confronting emergency collision hazards. However, a gap exists in our understanding of the movement characteristics of a collision hazard that directly contribute to a driver’s decision to initiate an evasive response. The aim of this experiment is to examine how the movement characteristics of intruding vehicles affect an oncoming driver’s PRT interval. Fourteen subjects viewed first-person perspective recordings of a simulated vehicle travelling along a two-lane roadway. Collision hazards were introduced when stopped vehicles positioned at intersecting roadways unexpectedly intruded into the subject’s path. Subjects were instructed to ‘brake’ their vehicle by pressing a keyboard space bar when they perceived that evasive actions were required to avoid a collision.
Journal Article

Validation of a PC-Crash Multibody Sport Bike Motorcycle Model

2021-04-06
2021-01-0893
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

Mobility in mining: Issues for road safety improvement

2021-03-26
2020-36-0125
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

Characterizing Regenerative Coast-Down Deceleration in Tesla Model 3, S, and X

2020-04-14
2020-01-0883
Tesla Motors vehicles utilize a regenerative braking system to increase mileage per charge. The system is designed to convert the vehicles’ kinetic energy during coast-down into electrical potential energy by using rotational wheel motion to charge the batteries, resulting in moderate deceleration. During this coast-down, the system will activate the brake lights to notify following vehicles of deceleration. The goals of this study were to analyze and quantify the regenerative braking behavior of the Tesla Model 3, S, and X, as well as the timing and activation criteria for the brake lights during the coast-down state. A total of seven Tesla vehicles (two Model 3, three Model S and two Model X) were tested in both Standard and Low regenerative braking modes. All three Tesla models exhibited similar three-phase behavior: an initial ramp-up phase, a steady-state phase, and a non-linear ramp-down phase at low road speeds. Phase 1 was less than one second in length.
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

Residual Injury Situation and Accident Characteristics of Severe Motorcycle Accidents

2019-04-02
2019-01-0638
The total number of persons severely and fatally injured in road traffic accidents has reduced considerably in recent decades. However, the number of motorcyclists involved in accidents has not reduced to the same extent, and some countries have even recorded an increase. The aim of this study is to analyse the circumstances of motorcycle accidents in Germany involving vehicles with a cubic capacity of over 125 cm3 with particular reference to severely or fatally injured riders. An analysis is to be made of the characteristics and patterns of injuries suffered by the most severely injured motorcyclists and proposals developed for injury prevention. The study included accident data from 464 motorcycle accidents collected in Hanover and Dresden between 2010 and 2015 by an academic research team in the course of the GIDAS project (German In-Depth Accident Study). This data represents a statistically representative sample from real accidents occurring in Germany.
Technical Paper

Accuracy and Sensitivity of Yaw Speed Analysis to Available Data

2019-04-02
2019-01-0417
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.
Journal Article

Reconstructing Vehicle Dynamics from On-Board Event Data

2019-04-02
2019-01-0632
These predictions were generated by directly integrating the VCH data and by using the VCH data as inputs to PC-Crash simulations. The predicted positions and headings were then compared to the actual position and heading data measured using differential GPS synchronized to the VCH data record.
Technical Paper

Estimating Benefits of LDW Systems Applied to Cross-Centerline Crashes

2018-04-03
2018-01-0512
Objective: Opposite-direction crashes can be extremely severe because opposing vehicles often have high relative speeds. The most common opposite direction crash scenario occurs when a driver departs their lane driving over the centerline and impacts a vehicle traveling in the opposite direction. This cross-centerline crash mode accounts for only 4% of all non-junction non-interchange crashes but 25% of serious injury crashes of the same type. One potential solution to this problem is the Lane Departure Warning (LDW) system which can monitor the position of the vehicle and provide a warning to the driver if they detect the vehicle is moving out of the lane. The objective of this study was to determine the potential benefits of deploying LDW systems fleet-wide for avoidance of cross-centerline crashes. Methods: In order to estimate the potential benefits of LDW for reduction of cross-centerline crashes, a comprehensive crash simulation model was developed.
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.
Standard

Rollover Testing Methods

2017-07-28
HISTORICAL
J2926_201707
The scope of this document is to provide an overview of the techniques found in the published literature for rollover testing and rollover crashworthiness evaluation at the vehicle and component levels. It is not a comprehensive literature review, but rather illustrates the techniques that are in use or have been used to evaluate rollover crashworthiness-related issues.
Technical Paper

Real-time Crash Detection and Its Application in Incident Reporting and Accident Reconstruction

2017-03-28
2017-01-1419
Characterizing or reconstructing incidents ranging from light to heavy crashes is one of the enablers for mobility solutions for fleet management, car-sharing, ride-hailing, insurance etc. While crashes involving airbag deployment are noticeable, light crashes without airbag deployment can be hidden and most drivers do not report these incidents. In this paper, we are using vehicle responses together with a dynamics model to trace back if abnormal forces have been applied to a vehicle so as to detect light crashes. The crash location around the perimeter of the vehicle, the direction of the crash force, and the severity of the crashes are all determined in real-time based on on-board sensor measurements which has further application in accident reconstruction. All of this information will be integrated to a feature called “Incident Report”, which enable reporting of minor accidents to the relevant entities such as insurance agencies, fleet managements, etc.
Technical Paper

Reconstruction of Pediatric Occupant Kinematic Responses Using Finite Element Method in a Real-World Lateral Impact

2017-03-28
2017-01-1462
Computational human body models, especially detailed finite element models are suitable for investigation of human body kinematic responses and injury mechanism. A real-world lateral vehicle-tree impact accident was reconstructed by using finite element method according to the accident description in the CIREN database. At first, a baseline vehicle FE model was modified and validated according to the NCAP lateral impact test. The interaction between the car and the tree in the accident was simulated using LS-Dyna software. Parameters that affect the simulation results, such as the initial pre-crash speed, impact direction, and the initial impact location on the vehicle, were analyzed. The parameters were determined by matching the simulated vehicle body deformations and kinematics to the accident reports.
Technical Paper

Design and Evaluation of an Affordable Seatbelt Retrofit for Motor Coach Occupant Safety

2017-01-10
2017-26-0018
Prevention of passenger ejection from motor coach seats in the case of rollover and frontal crashes is critical for minimizing fatalities and injuries. This paper proposes a novel concept of affordably retrofitting 3-point seatbelts to protect passengers during these significant crash scenarios. Currently, the available options involve replacement of either the entire fleet, which takes time to avoid extremely high costs, or all seats with new seats that have seatbelts which is still expensive. Alternatively, this paper presents the development of an innovative product that can be installed in seat belt-ready bus structures at a fraction of the cost. The efficacy of the design is studied using finite element analysis (FEA) to meet Federal Motor Vehicle Safety Standards (FMVSS) 210 standards for conditions involved in frontal and side impacts.
Technical Paper

Determination of Critical Speed, Slip Angle and Longitudinal Wheel Slip based on Yaw Marks Left by a Wheel with Zero Tire Pressure

2016-04-05
2016-01-1480
This article presents the results of an analysis of the yaw marks left by a car with normal pressure in all tires and then normal pressure in three tires and zero in one rear tire. The analysis is a continuation of research on influence of reduced tire pressure on car lateral dynamics in a passing maneuver, discussed in the SAE paper No. 2014-01-0466. Preliminary analysis of yaw marks has shown, that a wheel with zero pressure deposits a yaw mark whose geometry differs from the yaw mark made by a wheel with normal pressure based on which we could calculate: critical speed, slip angle and longitudinal wheel slip. The aim of the presented research was to analyze the yaw marks left by car with zero pressure in one rear wheel in order to check the possibility of determining the vehicle critical speed, slip angle and longitudinal wheel slip. It was reached by performing bench and road tests during which the vehicle motion parameters were recorded using GPS Data Logging System.
Technical Paper

Wrap Around Distance WAD of Pedestrian and Bicyclists and Relevance as Influence Parameter for Head Injuries

2015-04-14
2015-01-1461
During most pedestrian-vehicle crashes the car front impacts the pedestrian and the whole body wraps around the front shape of the car. This influences the head impact on the vehicle. Meanwhile the windscreen is a major impact point and tested in NCAP conditions. The severity of injuries is influenced by car impact speed; type of vehicle; stiffness and shape of the vehicle; nature of the front (such as the bumper height, bonnet height and length, windscreen frame); age and body height of the pedestrian; and standing position of the pedestrian relative to the vehicle front. The so called Wrap Around Distance WAD is one of the important measurements for the assessment of protection of pedestrians and of bicyclists as well because the kinematic of bicyclists is similar to that of pedestrians. For this study accidents of GIDAS were used to identify the importance of WAD for the resulting head injury severity of pedestrians and bicyclists.
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