Large trucks, commonly referred to as “big rigs,” “semi-trucks”
or “tractor trailer” trucks typically weigh 80,000 pounds
and range from approximately 67 to 75 feet in length. Despite that large
trucks represent only 3% of all registered vehicles on the road, they
account for over 25% of passenger vehicle occupant deaths in multiple
The tremendous difference in size and weight between passenger vehicles
and large trucks make visualization of catastrophic injury easy. However,
the difference in size and weight between passenger vehicles and large
trucks are at issue. For example, it will take a 40 ton 18-wheeler driving
at 65 miles an hour an additional 100 feet to stop than were it traveling
at 55 miles an hour. Given this, it is not surprising that typical big
rig accidents usually involve rear-end collisions. Jack-knifed trailers,
right hand squeeze, and brake failure are also common accidents involving
The Role of Bio-Mechanical Evidence and Recreation in Injury Trials
In the past 50 years, thousands of motorists and truck drivers have been
killed and/or injured in large trucking accidents primarily resulting
from driver error and negligent maintenance by trucking companies. Unsafe
driving, over-sized loads and other acts of negligence have put the public,
as well as, truck operators in danger.
California is one of approximately 10 states which impose a slower speed
limit for large trucks and commercial vehicles. Approximately 7% of all
of the vehicle miles driven in the nation are done so by large truck drivers.
Federal crash statistics have shown that at least 20% of large trucking
accidents are due to excessive speed. This is especially so when coupled
with problems resulting from excessive speed and braking.
Nonetheless, while mechanical failures, reckless driving and improper driver
training account for many of the crashes, the National Highway Transportation
Safety Association (NHTSA) reports that driver fatigue is responsible
for between 30% and 40% of all big rig crashes and is the probable cause
in over 30% of the crashes that resulted in the truck driver’s death.
Much like the tragic frequency of traumatic brain injury in this country,
every 16 minutes, each day, another person in the United States will be
injured or killed in a trucking-related accident. It is not surprising
that at least one-third of the injured suffer catastrophic harm and damage.
In 2003 alone, over 450,000 large trucks were involved in crashes. In
a survey done that year, almost 20% of truckers admitted to falling asleep
at the wheel at least once in the previous three-month period.
However, each year about 600 large truck occupants are killed and about
30,000 are injured in highway crashes according to data collected by NHTSA.
(This compares to approximately 5000 deaths resulting to passengers in
smaller vehicles involved with large trucks and over 140,000 injuries
per year to individuals operating smaller vehicles involved with large
Clearly, in multiple vehicle crashes, smaller vehicles and their occupants
are at a vast disadvantage when a large truck is involved. Nonetheless,
large truck safety should involve safety to big rig drivers and their
occupants as well as safety to smaller vehicles.
In 2004 alone, an estimated 200,000 new trucks had been registered to operate
on United States roads. One would hope that the registration of “newer”
vehicles would result in safer trucks. This is not necessarily the case
however. In many instances, the cabs of large trucks are designed to do
little more than keep out wind and rain. Relatively minor crashes, especially
those not involving other vehicles, can and do often result in catastrophic
injuries to truck operators and passengers. There is a dearth of federal
regulation or efforts by truck manufacturers or trucker trade unions to
provide rudimentary safety measures to protect truck drivers. Doors should
stay shut, windshields should not pop out, and some type of safety cage,
ought to be, but isn’t normally available.
Newly registered trucks and ever expanding fleets of trucks results in
greater competition. Drivers are under increased pressure to deliver faster
in order to remain competitive. While regulations state that a big-rig
operator can only “drive” for 10 hours per day, and must have
8 hours off for each 10 hours of driving, there is also load/unload time,
often involving hours of physical labor. It is no wonder that truckers
admit to falling asleep at the wheel. Many times the truckers’ 10
hours of driving begins after hours of physical labor getting the load
ready to go.
Unfortunately, when a 2000 pound automobile is involved in an accident
with an 80,000 pound tractor-trailer, even the best of passenger vehicle
design may not prevent catastrophic injury from resulting.
Scarlett Law Group has been involved in big rig accidents resulting from
improper maintenance, braking problems, driver error, jack-knife, lane
change error/blind spot, as well as fatigue. Despite that the resulting
harm to passenger vehicles and occupants is easily seen, the Scarlett
Law Group routinely utilizes the services of biomechanical engineers and
accident reconstructionists, as well as safety specialists, mechanics
and others in order to convincingly establish their clients’ cases.
Given the dramatic proportional difference between passenger vehicle and
big-rig, accidents involving alleged operator error, or mechanical error
in semi-tractor-trailers, generally these are vigorously defended. It
is not uncommon for the defense to point to driver error on the part of
the passenger vehicle operator. Did he or she cut in front of the truck?
Did he or she operate their passenger vehicle in a blind spot for an inordinate
amount of time? Was an improper passing technique utilized by the passenger vehicle?
While liability for many vehicular/trucking collisions is clear, accident
reconstruction and workup of the biomechanics of injury are nonetheless
required for proper trial presentation in virtually all such cases. Scarlett
Law Group works with top experts on this subject.
For example, many are surprised to learn that most SUVs and pickup trucks
maintain a rigid bumper system which clearly can result in much greater
injury to occupants in even low speed impact collisions.
The presence or absence of motor vehicle bumper damage is usually thought
to be an important consideration when estimating the severity of a low
speed, or minimal damage collision. There are, however, several types
of bumpers. Most passenger car bumpers contain elements designed to dissipate
the impact energy, such as shock absorber-like isolators, foam cores or
lattice cores. A number of studies have provided insight into analyzing
collisions involving these kinds of bumpers.
A rigid bumper system, such as contained on most SUV and pickup trucks,
typically consist of a steel bumper beam attached to the vehicle frame
either directly or by mounting brackets. Rigid bumpers are common on pickup
trucks, vans, and sport utility vehicles.
In one study, full-scale impact testing was selected as a method of investigating
the performance of rigid bumper systems during low-speed collisions. A
vehicle-to-vehicle test is clearly the best facsimile of the actual collision.
However, barrier impacts are widely used in mandatory standards compliance
tests, and the relative ease of conducting a barrier test makes it an
attractive alternative to a vehicle-to-vehicle test when assessing the
behavior of a rigid bumper.
In at least one study, comparison was made between the damage produced
in barrier and vehicle-to-vehicle tests of a similar severity to assess
the viability of barrier testing when analyzing real-world collisions
involving rigid bumpers. Scarlett Law Group, together with its experts,
maintains constant review of all literature in this area, and when re-enactment,
via computerized projection or actual vehicle reenactment is performed
for forensic purposes, Scarlett Law Group and their experts chooses the
most viable option available.
For example, in one study 5 pickup trucks were subjected to barrier impacts
and vehicle-to-vehicle impacts on both their front and rear bumpers. Prior
to each test, replacement bumpers and mounting hardware were installed
by a local auto body shop.
The vehicles tested included a 1980 Ford F-150 Pickup, a 1981 GMC C-1500
Pickup, a 1983 Toyota Half-Ton Pickup, a 1983 Chevrolet S-10 Pickup, a
1984 Ford Ranger, and a 1993 Ford Crown Victoria. Original manufactured
equipment and parts were used for all of the vehicles.
Speed, damage, and high-speed video were recorded for each test. Impact
force was recorded for the barrier test.
A MacInnis Engineering Associates “fifth wheel” was attached
to each test vehicle to measure speed during the collisions. Collected
at 256Hz, this device provides speed resolution of about 0.04km/h.
The barrier was equipped with two uni-axial lode cells to measure impact
force. This data was collected at 256Hz.
All test vehicles were weighted axle-by-axle using an 11kN load cell with
a resolution of 10N.
Video of the bumper’s impacts was recorded using an omniSpeed HS
motion capture system and high speed digital cameras. Video data were
recorded at 250 frames per second, using a shutter speed of 1/1000.
First, the front and rear barrier impacts were conducted with all vehicles,
followed by front and rear impacts with the rear and front bumpers, respectively,
of the 1993 Ford Crown Victoria 4-door sedan.
The test vehicles were pulled into impact by a speed controlled electronic
winch and a steel cable attached to the undercarriage. Just prior to impact,
the winch was turned off, so the vehicle coasted into contact.
The barrier consisted of a horizontal steel beam with a rectangular cross-section
attached by two lode cells to a rigid frame. The frame was bolted to a
concrete floor. The height of the impact beam was adjusted so that the
center of the beam was approximately level with mid-height of the bumper.
A 1993 Ford Crown Victoria was used for vehicle-to-vehicle collision with
the pickup trucks. In each of the rear bumper tests, a stationary pickup
truck was struck by the front of the Crown Victoria. The Crown Victoria
was towed to the required speed by the electric winch, and released just
before impact. For each front bumper test, the pickup truck was towed
into the rear of the stationary Crown Victoria in a similar manner.
The striking vehicle impact speed for each vehicle-to-vehicle test was
selected so that the speed change experienced by the pickup truck would
nearly match the speed change observed in the corresponding barrier test.
Coefficients of resolution were predicted using approved methodology.
The striking and target vehicle bumper heights matched in all tests.
The differences between the damage caused in the vehicle and barrier tests
was found to be generally attributable to the difference in the shape
of the barrier and the Crown Victoria’s bumpers. The Crown Victoria’s
bumpers were curved and these curvatures resulted in non-uniform loading
of the bumper beam and the mounting brackets. In many of the tests the
horizontal curvature caused greater deformation between the bumper mounts
than the barrier test.
The bumper damage was similar in the vehicle and barrier tests if the bumper
mounts buckled. The exception was the Toyota rear bumper, which rotated
in opposite directions in both vehicle and barrier tests, though with
about equal magnitude. However, if the bumper mounts did not fail, or
if the bumper was mounted directly to the frame rails, then bumper damage
was different in the vehicle and barrier tests. In these cases, the bumper
beams tended to bow between the unyielding mounts and when contacted by
the rounded vehicle bumper, they remained flat after the barrier impact.
The test data presented in this study established that both front and rear
bumpers of five pickup trucks sustained at least localized damage when
subjected to nominal 8km/h speed changes in collisions with a fixed barrier
or another vehicle. Full-sized pickup trucks sustained less bumper damage
than compact trucks for equivalent speed changes, though there was variation
in compact truck performance. Nonetheless, given the rigid nature of the
bumper itself, little damage to the bumper did not equate to the forces
subject to the occupants of the vehicles itself. In fact, through utilization
of appropriate biomechanical testing, it was determined that the absence
of bumper damage on a rigidly mounted bumper did not in any way rule out
the probability of serious injury, including brain injury, to the occupants therein.
Accordingly, by utilizing appropriate experts, and by staying abreast of
current literature, Scarlett Law Group is able to educate juries as to
why serious injuries occur with seemingly little property damage.
Even in cases involving significant property damage, for example, where
the Jaws of Life has been utilized in order to extricate the occupants
of a vehicle, biomechanical analysis must still occur. Whether the collision
involves a large truck, a school bus, a pickup truck, or a small sedan,
Scarlett Law Group, and its team of experts, stand ready to assist you
in your time of need.
In any large truck/passenger car accident, even though you, or your loved
ones, have been seriously injured, do not expect that your conduct will
not be scrutinized by the defense. By reconstructing the accident, and
by employing appropriate bio-mechanical specialists, Scarlett Law Group
eliminates and eradicates misplaced defense arguments. If you, or a loved
one, have been in an accident involving a tractor trailer or a large truck,
Scarlett Law Group has the expertise to assist you through your difficult times.
If you or someone you know has been injured as the result of a trucking
accident, you need the assistance of Scarlett Law Group.
Contact us today to speak with a San Francisco truck accident attorney.