Accident reconstruction

Organized by Larry Coben and
Jim Ronca, lawyers at Anapol
Scientific Issues in
Schwartz.

© 2011 All Rights Reserved.
Motor Vehicle Cases
Reconstruction and Crashworthiness

The attorneys who call on accident reconstruction experts range from having absolutely
no idea what is going on to ones who can reconstruct the accident themselves. They are
not necessarily trained engineers or accident reconstructionists, but they have been deal-
ing with the field long enough to know the critical issues.

—Renfroe et al, The Role of Expert Witnesses in Accident Reconstruction Cases

Contact lawyer:
Jim Ronca
Contents
Email: Basic Concepts that Must Be Understood 2
jronca@anapolschwartz.com
Scientific Problem Solving 2
Toll Free: (866) 735-2792 Crash Investigation Data Points 3
Identifying the Problem 5
Read more information online
at: www.anapolschwartz.com
ATTORnEy DISCLAIMER: This PDF is dedicated to providing general public information regarding legal
rights. none of the information on this PDF is intended to be formal legal advice, nor the formation of a lawyer
or attorney client relationship. Please contact a lawyer for information regarding your particular case. This PDF is
not intended to solicit clients outside the states of Pennsylvania, new Jersey, Ohio, West Virginia and Arizona.

BasiC ConCepts that Must sCientifiC proBleM solving
Be understood Herman Gordon

• Delta V 1. Understand the problem
• Acceleration/Deceleration • What are the data?
• Momentum • What are the unknowns?
• Force • What are the scientific principles that apply?
• Kinetic Energy • Can the problem be solved?
• Induced Damage 2. Assumptions
• Crush Energy • What can you or need you assume?
• Coefficient of Friction • What shouldn’t you assume?
• Skid Marks • Have you made subconscious assumptions?
• yaw 3. Devise a plan of attack
• Principal Direction of Force • Have you seen this or a related problem before?
• Reference Point • Have you seen a similar unknown before?
• Critical Speed • If you can’t solve this problem, can you solve a simpler
• Perception/Reaction problem or part of the problem?
• Drag Factor 4. Review
• newton Three Laws: • Are you sure of the solution? Can you see it at a
1. Inertia glance?
2. Bodies subject to a constant force • Did you use all of the data?
3. Equal and opposite reactions • Can you get the same solution another way?
• Are there other valid solutions?

SCIEnTIFIC ISSUES In MOTOR VEHICLE CASES
Copyright © 2004–2011 All rights reserved. Anapol Schwartz.
Read more information online at www.anapolschwartz.com.
2

Crash investigation data points
1. Human factors information 3. Visual obstructions
a. Perception time a. Weather—fog etc.
b. Detection b. Lighting conditions
c. Identification c. Ambient light
d. Decision d. Artificial illumination
e. Response e. Headlights
f. Reaction time f. Alignment
g. Driver experience g. How clean
h. Driver general health condition including disabilities h. Physical obstructions
i. Driver alertness i. Dirt on windshield
j. Driver distractions j. Background “noise”
k. Visual acuity k. Visual distractions
l. Field of vision l. Glare
m. Depth perception
n. Contrast sensitivity 4. Scene
o. Visual adaptation a. Type of road surface
a. Alcohol or drugs b. Condition of roadway surface
1. Smooth, bumps, potholes etc.
2. Vehicle 2. dry, wet , snow, ice
a. Type—passenger car, straight truck, tractor trailer, c. Alignment of roadway
motorcycle, towing d. Pitch of roadway
b. number of axles e. Markings on roadway , lines etc.
c. Load f. Traffic control devices
d. Type of cargo 1. traffic signal sequence
e. Vehicles defects 2. traffic detectors
f. Headlights g. Gouge marks, scrapes, scratches
g. Steering h. Holes and grooves
h. Brakes i. Tire marks
i. Tires j. Skid
j. Suspension k. yaw
k. Windshield wipers l. Sideslip
l. Undercarriage m. Striation
n. Scuff
o. Bloodstain pattern

(continued on next page)

3

5. Vehicle inspection 7. Injuries
a. Paint chips and paint transfers a. Size, shape, number and location
b. Marking on vehicles b. Presence of foreign material such as oil or paint
c. Impact damage c. nature and extent of internal injuries
d. Glass damage d. Interior contact points
e. Hairs and fibers e. Safety restraint injuries
f. Blood stains
g. Airbags deployed? 8. Pedestrians
h. Seat belt use a. Clothing
i. Bulbs b. Primary point of impact
j. Reflectors c. Secondary point of impact
k. Steering
l. Tires 9. Conspicuity
1. condition
2. inflation 10. Accuracy, Errors, Tolerances
m. Wheel alignment
n. Mirrors 11. Other areas with their own additional subsets
o. ECM a. Trucks
p. Horn b. Motorcycles
c. Fires
6. Investigation
a. Field sketches
b. Scale plan drawings
c. Total Station or other mapping
d. Photos
e. Aerial photos (including Google Maps and other
images available on the internet
f. Video cameras
g. Statements of drivers, passengers and witnesses
h. Physical evidence
i. Vehicle damage and appraisal reports
j. Vehicle examination reports
k. Weather reports
l. Information from injuries
m. Location of injured person (driver, passenger, front
seat, back seat, ejected, pedestrian etc.)

4

identifying the proBleM

Problem 1

Problem 2

Police report says all tire marks on road and median relate to bus
except on mark on the extreme right of diagram at edge of center
lane

Schoolbus
Final Rest Bus
Bobtail Truck

Final Rest Truck

5

Police Report
Police Report

Statement

At that point, I’m slowing down cause I know this isn’t going to be good. The truck was pretty solid. Right
there in the center lane and his brakes came on so he was slowing down, stepping on the brake and then what
happened next is really hard for me to understand why, but I saw the bus turn towards the right.

Deposition

Lawyer: “The truck never moved towards his lane, the truck stayed in his lane?”

Witness: “The truck was solid, you know, on the center lane, slowed down.”

6

7

Problem 3

“a crash is a series of events.”
— Evidence in Traffic Crash Investigation and Reconstruction, R. W. Rivers 2009

8

Problem 4

Driver unit #1’s story cannot be confirmed by accident reconstruction!

9

10

11

12

13

14

Aut
auto rotates around
o
the tandem tires

15

Accident reconstruction

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