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In this third edition of Vehicle Accident Analysis & Reconstruction Methods, Raymond M. Brach and R. Matthew Brach have expanded and updated their essential work for professionals in the field of accident reconstruction. Most accidents can be reconstructed effectively using of calculations and investigative and experimental data: the authors present the latest scientific, engineering, and mathematical reconstruction methods, providing a firm scientific foundation for practitioners. Accidents that cannot be reconstructed using the methods in this book are rare.
In recent decades, the field of crash reconstruction has been transformed through the use of technology. The advent of event data records (EDRs) on vehicles signaled the era of modern crash reconstruction, which utilizes the same physical evidence that was previously available as well as electronic data that are measured/captured before, during, and after the collision. There is increased demand for more professional and accurate reconstruction as more crash data is available from vehicle sensors. The third edition of this essential work includes a new chapter on the use of EDRs as well as examples using EDR data in accident reconstruction.
Early chapters feature foundational material that is necessary for the understanding of vehicle collisions and vehicle motion; later chapters present applications of the methods and include example reconstructions. As a result, Vehicle Accident Analysis & Reconstruction Methods remains the definitive resource in accident reconstruction.
Author(s): R. Matthew Brach, Raymond M. Brach, James J. Mason
Edition: 3
Publisher: SAE International
Year: 2022
Language: English
Pages: 597
City: Warrendale
Cover
Title Page
Copyright Page
Dedication Page
Contents
Foreword
Preface to the Third Edition
Preface to Second Edition
Preface to First Edition
Acknowledgments
CHAPTER 1 Uncertainty and Sensitivity in Measurements and Calculations in Accident Reconstruction
Introduction
Upper and Lower Bounds Using a Given Model
Differential Variations
Statistics of Related Variables
Linear Functions
Arbitrary Functions (Approximate Method)
Finite Differences
Monte Carlo Method
Design of Experiments
The Bayesian Method
Application Issues and Other Considerations
Other Methods of Evaluating Uncertainty
CHAPTER 2 Tire Forces
Introduction
Rolling Resistance
Slip, Longitudinal Force, and Lateral Force
Longitudinal Slip
Comments, the Coefficient of Friction, and the Frictional Drag Coefficient
Longitudinal Tire Force
Vehicle Event Data Recorders and Longitudinal Slip
Lateral Tire Force
Friction Circle and Friction Ellipse
Idealized Friction Circle and Idealized Friction Ellipse
Friction Circle and Friction Ellipse
Modeling Combined Steering and Braking Tire Forces
The Bakker-Nyborg-Pacejka Model for Lateral and Longitudinal Tire Forces
Modified Nicolas-Comstock Combined Tire Force Model
Application Issues
Tire Stiffness Values
Antilock Braking Systems
Light Vehicle (LV) Frictional Drag Coefficients
Frictional Drag Coefficients for Heavy Trucks (HT)
Hydroplaning
Appendix 2A
CHAPTER 3 Straight-Line Motion
Introduction
Uniform Acceleration and Braking Motion
Equations of Constant Acceleration
Road Grade and Equivalent Drag Coefficients
Vehicle Forward-Motion Performance Equations
Stopping Distance
Distance from Speed
Speed from Distance
Application Issues
Stopping Distance
Two Objects Decelerating While in Contact
Motion Around Curves
Vehicle Fall Equations
Equations of Motion of a Projectile
Equations of Motion of a Vehicle Leading to a Fall Including Rotational Inertia
CHAPTER 4 Critical Speed from Tire Yaw Marks
Introduction
Estimation of Speed from Yaw Marks
Yaw Marks
Radius from Yaw Marks
Critical Speed
CSF on a Flat Surface
Roadway with Superelevation
Application Issues
Tire Marks in Practice
Other Curved Tire Marks
Frictional Drag Coefficient, f
Driver Control Modes
Tire Forces in a Severe Yaw
The Critical Speed Formula and Edge Drop-Off (Road-Edge Reentry)
Uncertainty of Critical Speed Calculations
Estimation of Uncertainty by Differential Variations
Accuracy of the Critical Speed Method
Statistical Variations
Yaw Mark Striations
Striation Angles
Striation Spacing
CHAPTER 5 Reconstruction of Vehicular Rollover Accidents
Introduction
Rollover Test Methods
Documentation of the Accident Site
Documentation of the Accident Vehicle
Pre-trip Phase
Tire Mark Striation
Trip Phase
Modeling the Trip Phase
Complex Vehicle Trip Models
Rim Contact
Roll Phase
Speed Analysis for the Roll Phase
Determining the Roll Motion of the Vehicle
Generating a Realistic Roll Velocity Curve
Example Rollover Reconstruction
Vehicle-to-Ground Impact Model
Impulse Ratio (μ)
Impact Angle (ϕ)
CHAPTER 6 Analysis of Collisions, Impulse-Momentum Theory
Introduction
Quantitative Concepts
Point-Mass Impulse-Momentum Collision Theory
Coefficient of Restitution, Frictionless Point-Mass Collisions
Collisions Where Sliding Ends before Separation: The Critical Impulse Ratio, μ0
Sideswipe Collisions and Common-Velocity Conditions
Controlled Collisions
Coefficients of Restitution
Stiffness Equivalent Collision Coefficient of Restitution
Mass Equivalent Collision Coefficient of Restitution
Summary of the Point-Mass Impact Model
Planar Impact Mechanics
Overview of Planar Impact Mechanics Model
Application Issues: Coefficients, Dimensions, and Angles
Coefficient of Restitution and Impulse Ratio
Distances, Angles, and Point C
Work of Impulses and Energy Loss (Crush Energy)
RICSAC Collisions
Summary of Planar Impact Mechanics Model
Application Issues
Crashes with Large Mass Disparity between the Vehicles
Underride/Override Crashes
CHAPTER 7 Event Data Recorders and Crash Reconstruction
Introduction
Light Vehicle EDR Data
EDR Reported ΔV
Recording Delay
Incomplete Recording
Clipping
Effect of ACM Location
EDR Reported Precrash Vehicle Speed
Heavy Vehicle EDR Data
Summary
CHAPTER 8 Reconstruction Applications, Impulse-Momentum Theory
Introduction
Point-Mass Collision Applications
Rigid Body, PIM Applications: Vehicle Collisions with Rotation
Collision Reconstruction Using a Solution of the Planar Impact Equations
Reconstructions Using a Spreadsheet Solution of the Planar Impact Equations
Optimization Methods for Collision Reconstruction
Low-Speed In-Line (Central) Collisions
In-Line Impulse-Momentum Impact Model
Bumper Pair Stiffness Characterization Method
Airbags, Event Data Recorders, and ΔV
Crash Data
Precrash Data
CHAPTER 9 Collisions of Articulated Vehicles, Impulse-Momentum Theory
Introduction
Assumptions for Application of Planar Impact Mechanics to Articulated Vehicles
Articulated Vehicle Impact Equations
Validation of the Articulated Vehicle Impact Equations Using Experimental Data
Appendix 9A: Data Sheets for Example 9.4
CHAPTER 10 Crush Energy and ΔV
Introduction
The CRASH3 Method
Crush Stiffness Coefficients Based on Average Crush from Rigid Barrier Tests
Application Issues
Crush Stiffness Coefficients from Vehicle-to-Vehicle Collisions
Damage to One Vehicle Unknown
Side Crush Stiffness Coefficients, Two-Vehicle, Front-to-Side Crash Tests
Nonlinear Models of Crush
Arbitrary Number of Crush Measurements
CHAPTER 11 Frontal Vehicle-Pedestrian Collisions
Introduction
General and Supplementary Information
Forward Projection (Type I) Model
Hybrid Wrap Model
Vehicle-Pedestrian Impact (Type II) Mechanics
Model
Pedestrian Motion
Vehicle Motion
Values of Physical Variables
Reconstruction (Hybrid) Model
Application to a Motorcycle Rider Thrown after Impact
CHAPTER 12 Photogrammetry for Accident Reconstruction
Introduction
Aerial Photography
Camera Matching
Planar Photogrammetry
Three-Dimensional (3D) Photogrammetry
Fundamental Information Related to Three-Dimensional (3D) Photogrammetry
Mathematical Basis of Three-Dimensional (3D) Photogrammetry
Projection Equations
Collinearity Equations
Coplanarity Equations
Multiple Image Considerations
Considerations of the Use of Three-Dimensional (3D) Photogrammetry in Practice
Summary
Appendix 12A: Projective Relation for Planar Photogrammetry
CHAPTER 13 Railroad Grade Crossing and Road Intersection Conflicts
Introduction
Clearing a Crossing or Intersection Using a Sight Triangle
Sight Distance for Stopping before a Crossing or Intersection
FHWA Grade-Crossing Equations
Stopping Distance
Stopping Sight Distance
Clearing Sight Distance
Locomotive Horn Sound Levels at Railroad Grade Crossings
Calculation of Horn Sound Levels at a Distance from a Point Source
Insertion Loss of Light Vehicles
CHAPTER 14 Vehicle Dynamic Simulation
Introduction
Light-Vehicle Side-Force Coefficients
Heavy-Vehicle Side-Force Coefficients
Sensitivity of the Model to Parameters
Planar Vehicle Dynamic Simulation
Tire Side-Force Stiffness Coefficients
Examples
Appendix 14A: Differential Equations of Planar Vehicular Motion
Notation
Appendix A: Units and Numbers
Use of SI (Metric Units of Measure in SAE Technical Papers)
Numbers, Significant Figures, and Rounding
Significant Figures
Rounding of Numbers
Consistency of Significant Figures When Adding and Subtracting
Consistency of Significant Figures When Multiplying and Dividing
Other Forms of Number Manipulation
Unit Conversions for Common Units
Appendix B: Glossary
Common Terms and Acronyms in Accident Reconstruction
References
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12
Chapter 13
Chapter 14
Appendix A
Appendix B
Bibliography
About the Authors
Index
BackCover
