12/18/2016
FORENSIC SURVEYING
FORENSIC SURVEYING
Part 2
BERNARD M. TELATOVICH, P.E., ESQ.
CONSULTING SERVICES &
INVESTIGATIONS, LLC
PART 2
New York January 2017
BERNARD M. TELATOVICH, P.E., ESQ.
What is Evidence?
• Evidence – any species of proof, or
probative matter, legally presented at a
trial of an issue, by the act of the parties
and through the median of witnesses,
records, documents, exhibits, concrete
objects etc. for the purpose of inducing
belief in the minds of the court or jury as to
their contention.
(TAYLOR V. HOWEARD, 111 R.I. 527, 304 a.2D 891,893)
( BLACKS LAW DICTIONARY)
What is Evidence- to the Surveyor?
• Evidence – the state of being evident,
plain, apparent, or notorious (WILSON)
• Evidence – something used to prove,
ascertain, or lend support to a fact,
circumstance, or situation. Anything
accepted in court that will aid in retracing
and fixing a boundary. Reliable data,
objects, or documents that can be applied
by the surveyor to locate the record
boundary.
(HERMANSEN)
Types of Evidence?
•
•
•
•
•
•
•
•
•
Primary
Secondary Prima facia Extrinsic
Parol
Direct
Circumstantial
Expert
Etc.
Original Evidence
Second Hand
assumed correct unless…
extraneous
verbal/testimonial
What is a Fact?
• Fact – a circumstance, event, or
occurrence as it actually takes or took
place, a physical object of appearance as
it actually exists or existed. An actual and
absolute reality. (WILSON)
• Fact – a thing done, an action performed
or an incident transpired; an event or
circumstance, an actual
happening…which has taken place.(BLACKS LAW)
• Fact – something you can prove. (Mr. TELATOVICH)
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Trier of Fact?
The Jury:
Who assists the trier or fact to understand
evidence that requires specialized knowledge or
training?
Court–Hearing Officer–Administrative Judge
Who is the trier of the Law? _____________
Why the EXPERT of course!!
Trier of the Law?
Forensic Experts
The Judge:
Recognize pertinent evidence at the site
Appropriate collection of evidence
Photographs
Preservation of Evidence
Understanding Methodology
Wood and Tree Evidence?
Tree references in property descriptions may be
treated as monumentation in the ground.
Terminus of the line is typically at the center of the
tree, unless the description indicates otherwise.
Line of trees planted as boundary line is admissible
in evidence.
If the tree is lost or destroyed, it should be treated
similar to any missing . (or stake?)
Stake Evidence
Stakes designated in a legal description
typically designate an imaginary point e.g.
stake along the side of the cartway
designating the r/w.
A placed stake fixes the corner similar to
monumentation
The issue relative to stakes is they are no
of a permanent nature.
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Scribe marks in trees and on
other features
Using Forensics Survey
- Who would use the information?
- How is the information used?
Marking are typical evidence that is used to
establish fact. Restated, it tells a story
about the survey.
- Can I be involved?
- ACCIDENT RECONSTRUCTION – what
is it?
INTRODUCTION TO ACCIDENT
RECONSTRUCTION PRINCIPLES
ACCIDENT CAUSATION
•Driver Tactics
PRESENTED BY:
BERNARD M. TELATOVICH, P.E., J.D.
CONSULTING SERVICES
& INVESTIGATIONS, LLC
758 REDFERN LANE, BETHLEHEM, PA 18017
610-533-9092
Abbreviations:
• Perceive
• Decide
• Perform
•Driver Strategies
• Human Factor – an action which increases the
probability of successful evasive tactics. The
motor vehicle code regulations are designed to
increase beneficial driving strategy.
Equations:
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Conditional
Factors
Contributing
to Traffic
Accident
Causes
Basic Mathematical Concepts
Acceleration
• Acceleration is
the change in
velocity over a
period of time.
1. Human Factors
2. Vehicle Factors
3. Environmental
Factors
This is the “Black Box” for a Flight recorder
Examples –using equations
Vehicle Speed • A Vehicle traveling 40
miles per hour will travel
how many feet per
second (fps)?
• 1 MPH = 1.47 fps
• 40 miles x 1. 47 fps =
58.8 fps
A vehicle traveling 40
MPH covers 58.8 feet
every second
• A vehicle traveling at 100
fps will travel how many
miles in one hour.
• 100 fps / 1.47 = 68 MPH
• In one hour this vehicle will
drive 68 miles.
• The biggest mistake is
made with this conversion.
Sight Distance Problem
Intersection Accident
• A vehicle at an
intersection (using
PENNDOT and AASHTO
standards) has available
sight distance of 540 feet.
The driver alleges he had
only 100 feet available
and saw the approaching
vehicle only as it hit him.
Do you believe the
statement?
For Discussion
• At a given speed a
vehicle travels 540 feet in
a given time. For
example.
• At 30 MPH – it takes
• t= 540/((30)(1.47)) = 12
sec. to travel 540 feet
• t=100/((30)(1.47)) = 2 ¼
sec. to travel 100 feet
•
•
•
a= dv/dt
e
i
a= (v - v ) / t
SEE HANDOUT
MATERIALS
Distance
Velocity
Velocity, a vector, is
the rate of change
of distance with
respect to time
Distance is a
linear
measurement
from some point.
d/t
v= dd/dt or
v e ² = vi ² + 2 a t
d=velocity x time
i
d = v t + ½ a t²
SEE HANDOUT
MATERIALS
SEE HANDOUT
MATERIALS
Practical Application
Time Distance analysis
• A driver is approaching a
light which has a
protected left signal that
stays green for 8
seconds. He alleges he
saw the arrow when he
went through the previous
green light 600 feet away.
Do you believe this driver
that alleges he still had
the left green arrow as he
went through the
intersection?
Solution
• If the speed limit is 35 MPH,
this vehicle is traveling at
51.5 fps (35 x 1.47) . It
would take him
approximately 11 2/3 sec.
(600/51.5) to travel that
distance. To travel the 600
feet in 8 seconds, the
vehicle would be traveling at
75 fps (600 feet/8 seconds)
or 51 MPH (75/1.47). Note
this does not account for
deceleration --
Acceleration - Deceleration
Acceleration
• F = ma
• a=f x g
• g=gravity 32.2 ft/sec/sec
• f=drag factor
– Normal
– High range
– Motorcycle
f=0.15
f=0.30
f= ?
Deceleration
• Engine braking f=0.080.10
• Max comfortable braking
f=0.3
• Coefficient of Friction
– Static v. Dynamic
– f=0.7-0.9
– Other factors – rain, ice etc.
SEE HANDOUT
MATERIALS
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Acceleration –DecelerationProblem
Kinetic Energy
V
KE
A vehicle accelerates from a
stop to 20.4 mph in 6.5
seconds. How fast is this
vehicle accelerating?
(ve - vi ) / t
(30-0)/6 = 4.6 ft/sec/sec
Why 30? (hint - units)
What is the drag factor for this
accelerating vehicle?
Restated – How many g-s is
this vehicle driver feeling?
1 g = 32.2 ft/sec/sec
So
a= (f ) (g)
f= a/g = 4.6/32.2
f= 0.14 (compare with prior
slide)
Skid Marks - Wikipedia
• A skid mark is the mark a tire makes
when a vehicle wheel stops rolling and
slides or spins on the surface of the
road……. In car accidents, skid marks are
caused by rubber being deposited on the
road, much like that of an eraser leaving
pieces of rubber on a paper.
• Skid mark (per the Traffic Accident
Investigation Manual) is usually bitumen
softened by friction generated heat and
Sample
Calculation
Using
Nomograph
Work
Work
30 f d
=MPH (miles/hour) – FPS (ft/sec)
=½mv²
= ½(W/g)(1.47 v)²
(A)
=Fxd
(B)
=(fW) *d
= KE (Kinetic Energy)
=V² therefore-d= V²/30f
_____
V=√(30fd)
f=V²/30d
Problem: You are told by the expert that the vehicle was skidding on
asphalt a distance of 300 feet and he calculated the Speed of the vehicle
at 80 MPH. Is this plausable? (hint – solve for f (0.71) is that
reasonable?) YES
Speed
required to
slow to a stop!
SEE
HANDOUT!
Vehicle Collisions
• Point of First Contact
• Point of Maximum Engagement
• Last Contact Point
• Full Impact – some part of colliding surfaces reach
the same speed during impact.
• Partial Impact – aka swipe
SEE
HANDOUT
• Thrust – force between a vehicle and another
object which results in collapse of vehicle parts
(damage)
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Skidding Vehicles
Examples of Skid Marks
• Often the speed of a vehicle can be
determined based upon skid marks.
• Skidmarks are tire friction marks made by
a tire that is sliding without rotation on a
surface. The mark may be made as a
result of braking or post collision damage.
SEE
HANDOUT
• There are a variety of skidmarks!
Yaw Marks
Example of Yaw Marks
• A Yaw mark is a scuffmark made on a surface by
a rotating tire which is slipping more or less
parallel to its axis.
• Yaw marks are often referred to as centrifugal
skidmarks, critical speed scuffmarks, or sideslip
marks.
__________
• The equation : V = √ 15 R (e + f) where
R=radius
e=superelevation (cross slope) and f = side friction
Example Problem
• What is the maximum comfortable turning
speed for a car turning at a radius of 50
feet.
___________
• V = √ 15 R (e + f)
• e= cross slope or super-elevation – assume 0
• f= comfortable = 0.30 max is approximately 0.70
• So _____________
• V = √ 15 x 50 ( 0+0.3)
= 15 MPH
Are we talking sideslip?
• What is the maximum comfortable turning speed for a
car turning at a radius of 50 feet.
• V = 15 MPH (See handout)
• Yaw Marks – indicate side slip – provide R (radius)
• Thus, solve for the speed assuming an “f”
• Use the 1st one third of the yaw to determine the
critical R
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Linear Momentum
Conservation of Linear Momentum
• Momentum is conserved in collisions
• Newton’s Laws
•
•
•
•
F = ma
a=∆V/∆t
F= m∆V/∆t
F∆t = m∆V
• So Impulse = the change in Momentum
•
•
•
•
F₁∆t = m₁∆V₁
F₂∆t = m₂∆V₂
F₁ = -F₂
Substitute the above into the top two and
add together
• m₁∆V + m₂∆V₂ = 0
• M₁+ M₂ = M₃ + M₄
• W₁V₁ + W₂V₂ = W₃V₃ + W₄V₄
Momentum – Key Points
Vehicle Collisions
• Momentum can only be used to determine the
pre and post-impact Velocity
• After Collision
y
Point of
Contact
V
1
V1’
x
• The result is Delta V (for each vehicle – injury
factor)
o
V2’
x
V2
• Angle of Departure is critical
• Velocity is a vector with magnitude and direction
(Speed is the resultant - magnitude)
Momentum – Points to Ponder
Vehicle Collision-Momentum
• Before Collision
• After Collision
y
Point of
Contact
y
o
V2
V1’
x
V
1
o
V2’
x
1. Momentum (P) = mass (in slugs) times velocity (V) - it’s a
vector quantity meaning it has magnitude and direction>
2. Momentum is always conserved – In any group of objects that
act upon each other, the total momentum before the action
equals the total momentum after the action.
3. In this analysis the approach and departure angles are critical.
How one determines this is very critical to the calculation. The
best evidence if this is typically marks on the road and vehicle
damage.
4. A reasonable representative range of approach and departure
angles makes the calculation more reliable (a reliable
range/sensitivity.)
5. Momentum analysis is less sensitive the closer the impact
angle is to 90 degrees, the closer the vehicles are in weight,
and when the vehicles move a reasonable distance after
impact.
6. Momentum is very sensitive when the weight of the vehicles
differ significantly, i.e. a large truck impacting a small vehicle.
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Accident Reconstruction Sketch
This is a typical 90 degree collision where the vehicles do not
remain together. The angles of approach are not very sensitive
(90 degrees – 80 degrees), however the angles of departure are
always critical in evaluating an accident. Weight shifts can
create a parabolic departure.
What do the vehicles look like?
ACCIDENT RECONSTRUCTON SKETCH
This is a typical 9o degree accident where the two vehicles remain
together. You can imagine the result to the drive in an accident like
this!!!!!!
ENERGY
• Work is a measure of
what effect the force
has on changing the
object
• Work is also defined
at the product of the
Force and the
distance through
which the force acts.
Barrier Equivalent Velocity
• Equivalent Barrier Speed (Barrier
Equivalent Velocity)
• Campbell – vehicle damage and dynamic
force deflection characteristics (stiffness)
of the vehicle structure could be used to
estimate the energy absorbed in
permanent (plastic) defamation of a
vehicle. The force deflection
characteristics (crush) of the vehicle
structure could be estimated from frontal
• The work equation:
• W= F times d = Fd
• F= force (lb, N)
• d= distance
(feet,meters)
• W= work (ft-lb, N-m)
Equivalent Barrier Speed
• The Energy is now
equated to the Kinetic
Energy a vehicle
would have to
possess in a barrier
impact test.
• This velocity is called
EQUIVALENT
BARRIER
SPEED
- EBS
• We obtain the value in
the following units
(in-lbs) convert to (ftlbs)
_______
• EBS = v = √ (2gE/w)
• The result is the EBS
for each vehicle at
impact!
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RELATIONSHIP BETWEEN WORK AND
ENERGY
• Energy is
transferred
between different
objects by doing
work. The greater
energy an object
possesses, the
more work it can
perform.
ENERGY is
transferred
between different
objects by doing
WORK
THE LAW OF
CONSERVATIO
N
OF ENGERY
ENERGY MAY
BE NEITHER
CREATED OR
DESTROYED
• Example – a
Vehicle
accelerating gains
velocity and thus
has an increase in
energy. This is
called Kinetic
Energy. Also, when
a Vehicle slows, it
loses velocity, and
thus loses energy.
1. REST ENERGY- ENERGY POSSESSED DUE
TO AN OBJECT’S MASS (Remember E=mc²)
2. KINETIC ENGERY – ENERGY POSSESSED
DUE TO AN OBJECT’S MOTION
(KE=wv²/2g) and (W=wfd)
2. POTENTIAL ENERGY - ENERGY
POSSESSED DUE TO POSITION (PE=wh)
Determining Speed of Vehicles from
the Damage received in Traffic
Accidents
The most commonly used example
is the pendulum:
We are now talking about the concept of WORK
and ENERGY
This concept is totally different than MOMENTUM.
MOMENTUM can be used to determine pre-and
post impact velocity – it has speed and direction
– vector
WORK or ENERGY is a scaler quantity- the
product of the magnitudes of force and direction.
WORK
applied?
SKID MARKS - WORK
SKID MARKS
W=Fd
and F=ma
so W = mad
v e= v I+ ½ a t
but d= v I t + ½ a t
(V I = 0)
so t = V e / a and
d = ½ a V e /a(squared)
DRUM ROLL
PLEASE
V = √ 2 a d or in MPH
• W=Fd and F=ma
•
so W = mad
•
ve=vI+½at
•
but d= v I t + ½ a t
•
(V I = 0)
•
so t = V e / a and
•
d = ½ a V e /a(squared)
____________
V = √ 30 f d
•
•
____
Drum Roll Please: V = √ 2 a d or in MPH
V = √ 30 f d
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DAMAGED SUV – Damage
Profiles
DAMAGED SUV – LASER SCAN
TOP VIEW
DAMAGED SUV – LASER SURVEY
VEHICLE DAMAGE PROFILES
DAMAGE PROFILE - SUV
DAMAGE
PROFILE AUTOMOBILE
DAMAGED AUTOMOBILE -1ST SCAN
DAMAGED AUTOMOBILE – LASER
SCAN
TOP VIEW
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What information is needed for an analysis
using “Crush”?
The Equation : C=a+bv where
Mason 1972
C= Crush (in.)
a = constant
b = constant
v= impact speed (MPH)
Campbell’s Equation : v= bo + b1C which rearranged looks something like
this
₂
₂
E =₂ W/5[5G + A/2(C1
+ 2 C2 + 2C3 + 2C4 + 2C5 + C6) + B/6 (C1
₂
₂
₂
₂
+2C2 + 2C3 + 2C4 + 2C5 + C6 +C1C2 + C2C3+C3C4 + C4C5 +
C5C6)] (1+ tan Ѳ)
What do the variables mean?
• E = Energy dissipated
• G= A 2/2B
• W= Width of the Crush
Region
• A= The maximum force
per inch of width which
will not cause permanent
damage (lb/in.)
• B= The spring stiffness
per inch of damage width
(lb/in )
• Ѳ = Angle between the
principle direction of force
and perpendicular.
• C1 through C6 –
Measurements of
crush across the
crush region!
2
VEHICLE COLLISION-FULL
IMPACT
Postcollision
vehicle
positions!
Occupant Dynamics
What direction was Vehicle 2 going?
•
A vehicle decelerates from 30 MPH to 0 MPH. The crush damages
is 24 inches. How many g’s will the vehicle develop.
• f= V² / (30(d)) = 900/30(2) = 15 g’s
The unbelted drivers head hits the windshield and puts a 4”
indentation into the windshield. How many g’s is the drivers
head exposed to.
f= V²/(30(d)) = (900)/(30 x .33) = 90 g’s
Would you believe the expert that opined that
Vehicle 2 was turning left at the time?
Note the time over which a collision occurs is important in
determining the susceptibility to injury.
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REACTION TIME
• Think in terms of perception and reaction
• Perception of a hazard.
• Initiation of avoidance maneuver.
• Olsen studies Human Factors
Simple reaction time - RT = 1 sec to 1.5 sec –AASHTO
Complex reaction time – RT > 1.5 sec, 2.5 sec??
Total Stopping distance = d (RT) + d (Braking)
Pedestrian Accidents
• Pedestrian Vehicle Impacts
• At collisions below 12 MPH Pedestrians
sustain only minor injuries.
• At speeds above 27 MPH Pedestrian
collisions often end in a fatality (Wood,
Otte)
• Why? KE = f (V²)
Skippy the dummy- hit by car!
Pedestrian Kinematics
• Wrap Projections (pedestrian and car at
same speed, the a disassociation)
• Fender Vault
• Forward Projections (e.g. hit by a bus or
van)
• Roof Vault (e.g. car goes under the
pedestrian)
Searle’s – The Trajectories of
Pedestrians, Motorcycles,
Motorcyclists, etc., following a
Road Accident.
Pedestrian Trajectory Equations
Fall Equation :
v = d √ (g) / (2(d G –h))
where v =initial velocity (ft/sec)
i
f
g = acceleration due to gravity 32.2ft/sec²
d=
f
while
• Vmin = √ (2 µ g s )/(1 + µ²)
f
i
horizontal distance body traveled
falling (ft)
G = percent grade (often use 0)
h = height the center of mass falls (note – negative
if below take off positions
Slide Equation ;
v = √ (v )² - 2a d
where v =end velocity (ft/sec)
d = horizontal distance body traveled
while
sliding
(ft)
i
e
s
e
• V max = √ (2 µ g s )
f
Other Equations : Rau et al, Toor and Arasewski, Simms et.al., Wood,
PC Crash, Madymo V6.0
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Pedestrian Accident Facts
• Leg Fractures first occur in healthy young
adults at a speed of approximately 14 MPH.
• Multiple Severe fractures occur at speeds of
approximately 25 MPH or greater.
• Leg fractures most likely occur from colliding
with the bumper of a striking vehicle.
Pedestrian Drag Factors
• See Searle Study 0.66 ?
• Sliding body – 0.6 to 0.8
(Type of clothing has an effect)
• Tumbling body – 1.0
• The secondary impact of a pedestrian with
the roadway can cause more severe injuries
than the vehicle.
How did this happen?
• Why are they different?
Thank you!
QUESTIONS?
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