Vehicle Crash Reconstruction Methods     


I.D.# C1417Printable Description
Duration: 3 Days
Upcoming open enrollment dates being scheduled. Please check back.

Hotel & Travel Information

Automotive crash reconstruction is a process carried out with the specific purpose of estimating in both a qualitative and quantitative manner how a crash occurred. Reconstructions are based on data collected during the crash and physical evidence gathered during a crash investigation. To some extent, testimonial evidence is also used. Whether a crash is between two vehicles, a vehicle and pedestrian or a vehicle and a barrier, specific crash segments, classified as pre-impact, impact and post-impact motion often are reconstructed separately. Each of the segments is analyzed using established engineering, scientific and mathematical principles and based on the physical evidence. Not only must each method be well established, but it must be selected so its coverage corresponds to the conditions of the physical conditions. Three main factors - human, vehicle and environment are taken into account during a reconstruction.

This seminar is devoted to the exposition, use and limitations of the engineering, scientific and mathematical principles and methods used to reconstruct vehicle crashes. The primary objective is to help the attendees achieve a high level of understanding of these methods. The course covers a wide range of topics including vehicle acceleration/deceleration, impact mechanics, Event Data Recorder (EDR) and Engine Control Module (ECM) technology, tire mechanics, vehicle-pedestrian impacts and topics from vehicle dynamics. Most of the calculations can be carried out using commonly available spreadsheet technology.

VCRware, a commercially available software based in Microsoft Excel and written by the instructors, will be provided to the attendees for class exercise use during the seminar. Attendees should bring a Windows-based laptop equipped with Excel 2003 or later. Attendees will also receive a copy of the instructors' book, Vehicle Accident Analysis and Reconstruction Methods, published by SAE International, 2011.

This course has been approved by the Accreditation Commission for Traffic Accident Reconstruction (ACTAR) for 20 Continuing Education Units (CEUs). Upon completion of this seminar, accredited reconstructionists should contact ACTAR, 800-809-3818, to request CEUs. As an ACTAR approved course, the fee for CEUs is reduced to $5.00.

Learning Objectives
By attending this seminar, attendees will be able to:

  • Describe the basic mechanics of collisions, including the differences between normal and tangential contact/interaction effects, restitution, energy loss, ΔV, PDOF, common velocity conditions and other topics.
  • Articulate the differences between point mass and rigid body impact analysis and when each can be applied, and should not be applied.
  • Recognize the critical differences between methods described in the field of Crash Reconstruction such as “Conservation of Linear Momentum” and “Planar Impact Mechanics”, the assumptions and limitations behind these methods and when and how they should, and should not, be used.
  • Formulate and solve impact problems to reconstruct crashes with Event Data Recorder (EDR) and/or Engine Control Module (ECM) data and use spreadsheet optimization technology to turn a crash analysis into a reconstruction.
  • Combine pedestrian and vehicle motion to reconstruct pedestrian collisions including situations where the point of impact is unknown.
  • Use planar photogrammetry to determine unknown points and paths from photographs and site measurements.
  • Describe tire forces and tire mechanics for braking/accelerating and steering including Antilock Braking System (ABS) operation.

Who Should Attend
This course is well-suited for persons just beginning to work in the area of crash reconstruction as well as persons already in the field who want to establish a more firm foundation in current crash reconstruction technology.

Attendees should have knowledge of mathematics, physics and mechanics at a level equivalent to a second-year of college.

Topical Outline

  • Straight-Line Motion
    • Equations of motion of two-axle vehicles including pitch motion and load transfer due to braking acceleration
    • Values of the frictional drag coefficient, f , (“drag factor”) of light vehicles and heavy trucks
  • Point Mass Collisions (COLM, Conservation of Linear Momentum)
    • Basic concepts and simple applications of impact theory: impulse, momentum, velocity change, ΔV, energy loss, normal & tangential impulses (and the impulse ratio)
  • Planar Impact Mechanics (PIM)
    • Thorough coverage of the system equations and solution equations of impulse and momentum for the collision of two vehicles including rotational inertia and angular momentum which are essential for the analysis and reconstruction of crashes using EDR data
  • Class exercises using VCRware software

  • Crush and Tangential Energy Loss
    • Introduction to the concepts of crush measurements (CRASH3) to compute collision energy loss and its relationship to crash vehicle ΔV
  • Event Data Recorder (EDR) Technology
    • Introduction to the general characteristics of EDRs: driver and vehicle state data (settings), time intervals, pre-crash data, crash acceleration & ΔV
  • Crash Reconstruction using EDR Data, Planar Impact Mechanics and Spreadsheet Optimization Techniques
    • Use of Planar Impact Mechanics for analysis & reconstruction of crashes
    • Class exercise using VCRware software
  • Frontal Vehicle-Pedestrian Collisions
    • Introduction to and derivation of the equations of the Han-Brach pedestrian impact model and other pedestrian impact models, both empirical models and mechanics models
    • Class exercise using VCRware software

  • Planar Photogrammetry
    • Determination of road surface markings from photographs and site measurements
  • Mechanics and Modeling of Tire Forces
    • Description of longitudinal tire forces (braking/acceleration)
    • Lateral tire forces (steering/cornering) and tire forces under combined braking and steering
    • Friction ellipse
    • Modeling of tire forces using the Bakker-Nyborg-Pacejka (BNP) equations and the modified Nicolas-Comstock equations
    • Antilock braking principles
  • Critical Speed from Tire Yaw Marks
    • Description and measurement of yaw marks and reconstruction of vehicle speed at the beginning of yaw marks
  • Articulated Vehicle Impact
    • Concepts of impulse and momentum applied to crashes between articulated vehicles (such as tractor semitrailers) and other articulated vehicles, barriers or single vehicles
  • Topics from Vehicle Dynamics
    • Discussion of the bicycle model of a two-axle vehicle along with concepts of oversteer and understeer

Instructor(s): R. Matthew Brach and Raymond M. Brach
R. Matthew Brach

Matt is currently a Senior Managing Consultant for Engineering Systems, Inc. (ESI). His area of specialization includes vehicle impact analysis and dynamics and automotive crash reconstruction for both light and heavy vehicles. Matt has worked for Brach Engineering, Lawrence Technological University, Exponent Corporation, Ford Motor Company and MPC Products. He is a member of SAE International, American Society of Mechanical Engineers (ASME), National Association of Professional Accident Reconstruction Specialists (NAPARS), and the Institute of Electrical and Electronics Engineers (IEEE). He has a B.S. in Electrical Engineering from the University of Notre Dame, an M.S. in Mechanical Engineering from the University of Illinois-Chicago, and a Ph.D. in Mechanical Engineering from Michigan State University.

Raymond M. Brach

Ray is a Consultant for Engineering Systems, Inc. (ESI) and Professor Emeritus, University of Notre Dame. His areas of specialization include, vibrations, acoustics, and noise, mechanical engineering design, ground vehicle dynamics, applied mathematics and statistics, solid mechanics, mechanical impact dynamics, vehicle collision analysis, and crash reconstruction. He has authored and co-authored three technical books on the topics of mechanical impact, scientific uncertainty, and vehicle crash reconstruction. He is a member of SAE International, Acoustical Society of America (ASA), American Society of Mechanical Engineers (ASME), Institute of Noise Control Engineering (INCE), National Association of Professional Accident Reconstruction Specialists (NAPARS), and Tau Beta Pi, Sigma Xi, and Pi Tau Sigma.

Fees: $2180.00 ; SAE Members: $1744.00 - $1962.00

2.0 CEUs
You must complete all course contact hours and successfully pass the learning assessment to obtain CEUs.

For additional information, contact SAE Customer Service at 1-877-606-7323 (724/776-4970 outside the U.S. and Canada) or at

For a quote on bringing this course to your company site, fill out a Corporate Learning Solutions Request Form