Based on these figures, the researchers believe the RADS system would be cost-effective if there were an average five deer, three elk, or two moose collisions per mile annually, and assuming RADS could reduce the rate by 80 percent. The researchers believe the system is capable of that kind of reduction, and also that it might be particularly useful in rural areas, where animal-vehicle collisions make up almost 35 percent of collisions.

The California Department of Transportation is currently considering a system like RADS to deal with a herd of elk near McDonald Creek. "[The elk] take up quite a geographic span and occasionally cross the highway," says Anne Marie Jones, a spokesperson with the department. "That has led to a concentration of collisions."

Other animal-detection systems have been installed in more than 30 other locations around the world. But, according to the MSU researchers, most of them have technical difficulties, high maintenance requirements, or a lack of proper funding.

RADS is the first break-beam system to use microwave radio frequency signals. Others have relied on expensive infrared sensors or lasers, with their own limitations. For instance, laser systems can be difficult to align, sensitive in heavy fog, or cause eye damage, explains Bill Goodson, president of sensor manufacturer Goodson and Associates.

John Eddins, a district engineer at the Wyoming Department of Transportation, believes that operation and maintenance will be the key issues with sensor-based systems. "To keep all those devices working for a mile-and-a-half road is just tough," he says. "Keeping the snow off the lenses of the scopes, keeping water out of the pole boxes, keeping the system programmed correctly--it's going to be an issue."

His department purchased a different type of system in October 2005, which uses a combination of geophone and infrared sensors. The geophone sensors pick up foot-fall vibrations, while the infrared ones detect body heat. Both must detect an event together before warning signals will be activated.

Eddins remains optimistic about their system's reliability, which is estimated at 90 percent, and will be heading up a research project to test its effectiveness this winter on a 1.5 mile stretch of roadway in Pinedale, WY, where almost 70 percent of all collisions are related to mule deer and antelope.

Ultimately, researchers such as Eddins and Huijser hope to make the 21^st-century landscape safer for all travelers.