A
Rollover Warning System for Trucks?
A fully loaded,
18-wheeler truck rolls into a weigh station. Its weight is measured
in less than five minutes, but its brakes are not inspected thoroughly.
The weight satisfies regulations, but the tendency of the truck's brakes
to grab is not detected. The condition of the tractor-trailer rig's
brakes increases the chances that the driver could lose control, causing
an accident by jack-knifing or running into the wrong lane or off the
road.
"Faulty brakes
contribute to about one-third of truck-caused crashes in the United
States," says Scott Stevens, a researcher in ORNL's Energy Division.
"Current methods for brake inspection require too much time and labor
and are subject to error, so only a small fraction of the trucks on
the road are regularly checked."
Rollovers are
another kind of traffic accident that can prove deadly for truck drivers.
In the United States some 15,000 trucks a year roll over when drivers
approach a curve at too high a speed for the load being carried. According
to Stevens, "Truck rollover crashes are responsible for at least $3
billion a year in losses associated with death and injuries, property
damage, lost productivity, and lost time because of traffic backups."
Stevens and his
colleagues offer a partial solution: a truck testing technology that
quickly and accurately weighs trucks, inspects their brakes, and predicts
their chances of rolling over under various conditions. Stevens has
been working with University of Tennessee researchers Jeff Hodgson,
Steve Richards, and Matt Cate to design, build, and operate a prototype
advanced truck-testing facility. They believe that operation of this
facility will demonstrate that this technology, if widely used, could
greatly reduce the number of serious traffic accidents involving tractor-trailer
trucks.
The facility,
called the Multi-Plate Performance-Based Brake Tester, is being tested
for use by the commercial vehicle operations and vehicle and engine
research laboratories of the National Transportation Research Center
(NTRC). The goal is to show that, compared with conventional weigh-station
capabilities, this testing technology can weigh trucks more quickly
and provide faster and more accurate information on the condition of
truck brakes.
"If this technology
is used at most truck weigh stations," Stevens says, "state safety personnel
can comprehensively check the brakes of many more trucks without hiring
more staff. Our technology should be a credible deterrent to truck drivers
who delay getting their brakes checked and repaired. They will not want
to be caught with faulty brakes, which is a violation of the law, because
they don't want to be put out of service." The testing facility consists
of a platform over which a tractor-trailer rig can be driven so that
it can be weighed in a few seconds. To test the brakes, the driver is
asked to drive the truck onto the platform at 10 to 20 miles per hour
and brake sharply before leaving it.
 |
|
Model
truck and representation of a truck scale and brake tester to
be installed at NTRC.
|
The platform,
which is 24 m long (80 ft), consists of 48 steel plates laid down in
pairs, each of which measures about 1 m by 1.2 m (3 ft × 4 ft).
Underneath each steel plate are sensor rods with transducers that convert
the mechanical forces of the moving truck to corresponding electrical
signals. As a truck rolls over the platform, the sensors measure the
weight (vertical force due to gravity) and horizontal force on each
plate as the wheels come to a stop. The braking force is related to
the pressure exerted on the plates by each truck wheel during deceleration
and stopping. Four computers process the digitized measurements of braking
force to determine whether the truck's brakes are working well or failing.
The new NTRC facility
can also be used to determine the probability that a truck will roll
over at different speeds, based on its weight and load characteristics.
To test a loaded truck's rollover stability, the platform on which the
truck sits will be tilted to measure sideways forces, simulating the
effects of gravity on a truck winding around a curve. "Using this facility,"
Stevens says, "we will simulate the transfer of truck weight as a result
of lateral forces and calculate the effect of this shift on rollover
probability."
The researchers
think the results that will roll out of NTRC's truck testing facility
will show the value of its life-saving technologies.
A
Rollover Warning System for Trucks?
Scott Stevens and his
colleagues have been gathering data from three trucks they instrumented
that travel along the winding highway of Interstate 75. These "smart"
trucks have global positioning systems and instruments that measure
lateral acceleration for each position on a curve, whose characteristics
are broadcast to each truck from a roadside beacon set up by the researchers.
The smart trucks provide data that improve the researchers' ability
to estimate the risk of rollover.
Results from the
road tests and the facility experiments will be given to interested
industrial firms to enable them to devise a rollover warning system
for truck drivers. Such a system would sound an alarm if a driver is
approaching a curve too fast, allowing time for corrective action to
avoid rollover.
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