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Introduction
• Retired from Nevada Highway Patrol after 22year career, Reconstructing crashes since 1994.
• Nevada Resident since 1964
• Former race car driver and builder
• Former CDL truck driver
• Licensed motorcycle operator
• Avid road bicyclist
Paul Revere April 18th1775
>Like Mr. Revere, on this anniversary, Iwill attempt to give a succinctoverview of useful information.
What is an Expert?
• Definition:
• An individual of
recognized knowledge ina particular topic,typically confirmed byacademic standing andpublications, who iscalled upon by one ofthe parties to testify incourt as to his or her
opinion of theunderlying facts.
• Webster's Law actional
What Happened?
Levels of Law Enforcement
Investigation
• Untrained
• Basic Accident Investigation (POST)
• Advanced Accident Investigation
•Technical Accident Investigation
•Technical Accident Reconstruction (TAR)
• Reconstruction Certification (ACTAR)
Elements ofa crash
• Initial Driving behavior
• Hazard or possible hazard
•Reactionto hazard
• Point of no return
• Impact
• Position of rest
Reconstruction ThroughNorthwestern University
11 step process
1 Draw Vehicles to scale
2 Diagram Vehicle Damage (from photos)
3 Determine contact damage area
4 Estimate PDOF (thrust angle)
5 Determine post-impact rotation
6 Place vehicle diagrams
11 Step Process Continued
7 Compare direction and rate of rotation,estimate change in angles during crash.
8 Determine location of separation and rotation.
9 Match up vehicle information with evidence ondiagram.
10 Determine path of travel from separation tofinal position of rest.
11 Account for all signs of crash and explainevidence not associated with crash.
ActarAccreditation Commission for Traffic Accident Reconstruction
• The National Highway Traffic SafetyAdministration funded the first national
guidelines for the standardization training in thefield of traffic accident reconstruction in 1985.
This led to the establishment of Accreditation
Commission for Traffic Accident Reconstruction
(ACTAR), an industry accreditation group.(actar.org)
• Anyone can claim to be a reconstructionist.
Crash Analysis
• Evaluation of crash report
1Generate diagram
' Evaluate witness and driver statements
• Photographs
•Taken at Crash Scene
• Taken during scene visit
Determine contributing factors of crash
Four seconds prior to impact
Basic Speed formulas
•Energy
•Momentum
•Airborne vehicle
•Speed from a Yaw
•Speed from Skids
•Time-Distance
•EDR's
Evaluation of Crash Report
• Review crash report with care, looking for anyerrors or omissions.
• Helps to see officers abilities.
• Attention to detail.
• Level of training.
• Critical thinking skills.
• Analyze witness statements.
• Analyze photos.
• Digital photos are best.
Proofof Operation
1Placing Driver
• Did the driver admit to driving?
• Do statements given at scene and thosegiven later agree?
1Kinematics
• What was the movement of the
occupants or pedestrian post-impact
' Mostly related to criminal issues
Examination of Photographs
• More important as LE Agencies do lessDiagramming.
• Often reveal evidence overlooked at crash scene.
• Extremely useful in placing vehicles usingphotogrammetry.
• Google Earth or Bing Maps
• Additional photos should be taken by expert assoon as possible of vehicle and scene.
Complicated Crashes
•Pedestrian
•Bicycle
•Commercial Motor Vehicle
•Crashes without reports
• Light to no damage or evidence
• Multiple vehicle, multiple contact
Newton's Laws
• ALL crashes and mathematical formulas are
based on these three laws:
1 An object in motion stays in motion.
2 When force is applied to an object, the changein direction will be in the direction the force is
applied and inversely proportionate to the massof the object.
3 For every action, there is an equal and oppositereaction.
Delta V
•Term used for change in velocity.
• Velocity is a vector quantity having bothmagnitude and direction.
• Sudden changes are primary cause ofinjury
• Magnitude increases severity.
• Vehicles designed to absorb energy tolessen Delta V.
New Trends and Technology
• Forensic Mapping
• Event Data Recorders
• Photogrammetry
•Surveillance Video
Computers
•Math and formulas
• Diagrams
•Animations
• Derivation of formulas
General Motors Ignition Switch
• Currently subject of news coverage
• GM EDR's recording events since 1999
• Expert analysis of crash photos
• Crash reports
• Vehicle recalls
• -All 2005-2010 Chevrolet Cobalt
• -2005-2007 Pontiac G5
• -2003-2007 Saturn Ion
• -2006-2011 Chevrolet HHR
• -2006-2010 Pontiac Solstice
• -2007-2010 Saturn Sky
EDR, The "Black Box"
• Began in mid-1970's
• Accessibility limited by Manufacturer.
• Pending legislation
• Information stored in several locations
• 4-5 seconds prior to impact
• May save several events
• Primary use is confirming other information or togive a starting point
Questions?
ndaa.org/pdf/crash reconstruction basics.pdf
Actar.org
Nhtsa.gov
5afecar.org
