Avoiding Rear-End Collisions - Human Factors Psychologists Study How To Avoid Rear-End Collisions

May 1, 2008 — Psychologists studied the way a trailing driver reacts to a car braking directly in front of theirs and researchers developed an early warning system algorithm to prevent rear end crashes from occurring. They found that drivers cannot perceive the urgency of braking of the lead car and that this frequently leads to crashes.

If you spend a lot of time in traffic, chances are you've either had or almost had a traffic accident. One of the most common kinds of accidents are rear-end collisions. There were one-point-eight million of them in 2006 -- that's 29-percent of all the injury crashes in the United States; but now, researchers say they may be on the road to preventing them.

After more than 20 years of driving, Chris Palmer just had his first accident. He's far from alone. Multiple car crashes total over six million a year in the United States. Thirty-one percent are rear-end collisions. Since 2004, the Insurance Institute for Highway Safety has done simulations like this to test the safety of vehicles in rear-end crashes; but graduate student Nicholas Kelling wanted to know more about the human factors involved. Georgia tech engineering psychologists created this animation to simulate a rear-end collision scenario and test drivers' braking behavior. They found that drivers generally aren't able to detect when the car in front of them is going slower than they are, unless the difference in speed is at least eight to ten miles an hour.

"Well, if people can't detect that the car in front of them is going slower, you're going to run into it," Gregory Corso, Ph.D., a professor of psychology at the Georgia Institute of Technology in Atlanta, told Ivanhoe. Safety devices are designed to protect you if a crash happens, but now, these researchers have developed an algorithm they say could prevent many rear-end crashes from happening by creating a collision warning system that adjusts to the way you drive. "[It] incorporate[s] your driving style and your braking behavior and learn basically how you stop the car and modify its behavior to mimic your behavior," Dr. Corso explained.

"And we could put it into a warning system to tell people that the car in front of them is not going as fast as they are, and either stop the car or slow up," Nicholas Kelling, a graduate teaching assistant at the Georgia Institute of Technology, said.

Technology that could one day mean safer cars and fewer rear-end collisions. More than just dangerous, rear-end collisions carry a high price tag in the United States. The Insurance Institute for Highway Safety says the cost of treating neck and back injuries from rear-end collisions has spiked to $8.5 million a year.

COMPUTERS IN YOUR CAR: All modern cars have a computer, in charge of monitoring the various systems. This central computer receives information from a collection of sensors that monitor things like oxygen, air pressure, air temperature, and engine temperature, to name a few. Using this information, the computer can control the car's parts to get the best performance from the engine while keeping emissions low.

HOW DO SENSORS WORK? It depends on whether they are pressure sensitive or light sensitive. A pressure sensitive device can sense changes in pressure and emits an appropriate voltage in response to correct problems. These sorts of sensors are used in braking systems and collision avoidance systems, for example. Light-sensitive, or optical, sensors work very much like the wireless mouse technology in desktop computer systems. A small diode bounces light off a surface onto a sensor to form images. The sensor sends the data to a digital signal processor for analysis.

This processor can detect patterns in the images and figure out how they have changed since the previous image it received from the sensor. Based on the changes in patterns over time, the processor can determine how far the mouse, or car, for example, has moved. It can then send electrical signals to the central computer to trigger the appropriate response.

OTHER NEW APPLICATIONS FOR SENSORS: Sensors can scan the precise position of the driver's eye level and adjust the seat accordingly. Newer prototype cars include infrared light enhancers to improve night vision, as well as rearview mirrors and rear bumper sensors to alert the driver when other vehicles are approaching the car's blind spot. Adaptive headlamps contain sensors that monitor a car's speed and steering wheel movements and adjust lighting accordingly. For example, at high speeds, light beams are given a longer reach. Remain-in-lane systems use forward-facing cameras to monitor the car's position in relation to the road's centerline and side marker lines for 20 meters ahead of the car. If the car begins to veer out of the lane, the sensors detect this and set off a warning sound.

The Human Factors and Ergonomics Society contributed to the information contained in the video portion of this report.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Note: This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.