Penn State researchers are studying a new way to reduce tractor-trailer rollovers, which are the cause of many fatalities and hazardous waste spills on roads.
"When tractor-trailers are involved in an accident, there's such a great chance of fatality," said Scott Lewis, a researcher involved in the study. The study was actually a computer simulation that used a 75,000-pound tractor-trailer model to test the effects of differential breaking done by a computer that would prevent rollovers.
Lewis explained how rollovers could occur very simply. He said it is very similar to rounding a bend in a supermarket with a shopping cart too sharply. The cart will tip to the outside and could rollover.
"We're trying to devise a way to stop rollover," he said.
The computer simulation controls the rollover of the tractor-trailer by using its breaks. Much like antilock brake systems in cars, this system would add on to the brakes on the trailer and respond faster and more accurately than drivers could controlling the left and right breaks independently, called differential breaking.
"The system is designed to respond to rollover situations by applying torque and opposing the spinning direction of the truck," said Moustafa El-Gindy, a researcher with the study. "It applies different amounts of breaking forces."
"When you apply breaks to a truck, it's a lot different than a car; it's much harder to control," Lewis said. Braking becomes more difficult when the vechicle is hauling something behind it, Lewis said. "Now imagine that you have a vehicle behind you that weighs 50 times more."
The computer system isolates the breaking for each side of the trailer and tire, and reacts in ways that humans would not be able to. "The system is responding almost at the same speed as an anti-lock brake system; it's much faster than driver ability," El-Gindy said.
"You can't have different brakes for each axle, so the system controls when the ability of the driver stops," El-Gindy said. The system reacts without the driver; when the computer recognizes that a rollover situation is occurring, it responds. "It forces the vehicle to change direction without having to affect the driver steering."
El-Gindy said that the system will "establish a set of performance standards." Previous to this system, most standards have been passive standards, El-Gindy said, such as height and weight requirements.
"This computer system is an active system, it doesn't care about weight changes or tire wear; it reacts. Active systems are more applicable and safer," he said.
The system responds differently and appropriately for trailers with different heights, weights, tires and many other factors. Even shifts of weight in the load being carried are factored into the system.
The breaking system will also be applicable for sport utility vehicles and cars, El-Gindy said. "Mercedes and BMW are starting to look at differential breaking. It will add on to antilock break systems. " He said that this advancement will have many applications. "The whole concept is already accepted by the industry; it will gradually be the standard."
