July 27, 2005 By Sherry Watkins
A car approaches, but the driver is unaware of the obstruction -- a split second before impact, he catches a flash of shaggy brown fur in his headlights. Brakes squeal as the car careens into the animal's legs, sending its bulk over the hood and smashing through the windshield.
There are no survivors.
These collisions have several states asking how to prevent such tragedies, and concern about them helped launch a study to explore options for alerting drivers that a large animal could be blocking the roadway ahead.
The study, Animal Vehicle Crash Mitigation Using Advanced Technology, is being conducted by the Western Transportation Institute (WTI) at Montana State University, Bozeman, but is funded by 15 different transportation departments and the Federal Highway Administration.
Each contributor hopes to gain insight into the feasibility of installing animal detection systems along roadways to reduce vehicle collisions caused by animals blocking the right of way.
This isn't the first study using animal detection systems -- since 1993, Switzerland has installed several.
"Data from the seven sites in Switzerland showed an average reduction in ungulate-vehicle collisions of 82 percent," said Marcel Huijser, research ecologist at WTI and lead on the project. "These results are quite encouraging, but we still have some research questions with regard to the factors that may make a system more or less effective.
"For example, drivers are more likely to lower their speed if road and weather conditions are poor, and the warning signs may have to be accompanied by advisory or mandatory speed limit reductions," he continued. "The goal of the study is to evaluate the reliability and effectiveness of these animal detection systems, regardless of the outcome, positive or negative."
Crossing the Line
Animal detection systems use two primary technology types: area-cover sensors and break-the-beam sensors.
Area-cover sensors register the presence of large animals within a certain range of the sensor using infrared light or microwave radio signals. The sensors can be enhanced with specific algorithms capable of distinguishing between large animals and other moving objects that could potentially generate false detections, such as vehicles or hot pockets of air, Huijser explained.
Break-the-beam sensors are triggered once an animal breaks the beam sent between a transmitter and receiver, and includes infrared, laser or microwave radio signals.
The WTI system in place in Montana is located on a stretch of Highway 191 at Yellowstone National Park. This break-the-beam system uses low-power signals -- approximately 35.5 GHz. When an animal's presence breaks the beam, the signals transmitted to the receiver decrease, triggering the system and setting off warning lights.
This system requires direct line of sight, and the transmitter and receiver must be within one-quarter mile of each other. Solar panels provide the power for each, and excess power from the panels is stored in batteries, which lend power in the dark.
Upon animal detection, an ultra high frequency (UHF) signal is sent from the main station to the four stations nearby, causing the warning lights to flash.
"Within this one location at Yellowstone National Park, we've got a lot of elk movement, and it's clear they cross most in one section of the system," Huijser said. "They seem to prefer certain areas more than others. But this preference has not been very absolute, and where animals cross [the road] also depends on the species, because different species have different habits."
The system monitors detections, sending them via UHF radio signal in real time to the master station to be saved. This