Car, Truck, SUV, Motorcycle Accident Reconstruction Expert Witness

Crash Data Services, LLC

Providing quality traffic accident
investigation and reconstruction

US Roadways have a wide variety of motor
vehicle traffic. This makes for unique traffic
accident reconstruction scenarios involving,
sometimes, distinctly different vehicles.

The FHWA Traffic Monitoring Guide (TMG)
recommends classifying vehicles into 13
different categories based on vehicle
configuration. Class 13 heavy trucks can
have seven or more axles and gross vehicle
weight ratings (GVWRs) of 33,001 pounds or
more.

Small Class 1 motorcycles, can weigh as little
as 400 - 500 pounds. Passenger cars, light
trucks, and SUVs can have GVWRs
anywhere from a few thousand pounds up to
10,000 pounds.

The weight of colliding vehicles is an intricate
part of accident reconstruction. Certain
vehicle attributes, such as momentum, are
directly dependant on weight. Likewise,
certain methodologies of crash reconstruction
become increasingly sensitive as the weights
of colliding vehicles distance themselves.

And, not only do vehicle weights dramatically
affect accident reconstruction, but vehicle
equipment does as well. Anti-lock brake
systems (ABS), stability control, headlamp
type, automotive suspension, wheel base and
more can all influence the dynamic interaction
among vehicles during a collision.

For example, the friction value, sometime
referred to as drag factor, of a sliding or
skidding heavy truck can be significantly less
than the frictional value possessed by a
passenger car sliding or skidding on the
same surface. Our accident reconstruction
experts will provide relevant analysis of those
vehicle characteristics that influenced a crash.

In 2008, NHTSA appropriated almost 759 million dollars for grants promoting traffic safety. - NHTSA

Car, Truck, or SUV
Traffic Accident Reconstruction Expert

Accident reconstruction experts are
generally most concerned with dynamic
friction. Dynamic friction, also called
kinetic or sliding friction, is a measure of
the force resisting motion between two
sliding bodies. The friction caused
between a sliding tire and the underlying
road surface is one type of dynamic friction.

The proper assessment and application of
tire to roadway friction, sometimes referred
to as the coefficient of friction, is critical
when an expert accident reconstructionist
analyzes a collision. Vehicle ABS systems
attempt to maximize roadway friction by not
allowing a vehicle's wheels to lock. In most
cases, peak friction is actually reached just
prior to wheel lock-up. To view a graph of
an ABS vs Skid test, please click here.

The Federal Highway Administration
(FHWA) Traffic Monitoring Guide (TMG)
recommends classifying vehicles into 13
different categories. All States currently
use this classification scheme or some
variation of it for classifying vehicles. To
read FHWA's TMG, please click here.

Because of the wide variety of vehicles on
the road today, the Illinois Department of
Transportation (IL DOT) tracks fatal
accidents by vehicle type. To view Illinois'
2004 - 2008 fatal crash statistics by vehicle
type, please click here.