A “Virtual Fence” Has Halved A Highway's Roadkill


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

resting devil face

A trial to reduce roadkill was motivated by the need to save the Tasmanian Devil, but many other species benefitted as well. Gapvoy/Shutterstock

Australian scientists have demonstrated the effectiveness of an alarm system they call a “virtual fence”, which deters animals from crossing roads when cars are nearby. The idea isn't new, but the work suggests it has a much wider application than previously attempted.

Fast cars and wild animals don't mix well. For some rare species, being hit by cars as they attempt to cross roads is a major reason for their endangered status. The cost of damage to cars is substantial as well, and each year there are hundreds of human deaths (and many more injuries) worldwide. The Internet periodically gets excited about images of Dutch animal bridges, but their cost is enormous.


Some farmers have started to use “virtual fences” to stop their animals from straying. However, these involve putting collars on livestock that trigger when they stray too far, clearly not a practical approach for millions of native animals. However, an Austrian firm iPTE Traffic Solutions is producing a different sort of virtual fence, one with alarms to warn animals of a car's arrival. These mobile phone-sized units are placed 25 meters (80 feet) apart and produce flashing lights and noises pointed away from the road when a sensor detects a car's approach.

The technology was designed to prevent animals large enough to do serious damage to cars, such as deer or wild boar, from straying onto the roads. Dr Samantha Fox of Tasmania's Department of Primary Industries, Water and the Environment wondered whether it would be effective for the diversity of species living on the Tasmanian west coast.

In Australian Mammalogy, Fox describes a three-year trial where the alarms were installed along a 5-kilometer (3-mile) stretch of the Arthur River/Marrawah road. The number of animals found dead on the road was just over half that on unfenced sections of the same road.

The alarms en masse and installed. Tasmanian Department of Primary Industries, Parks, Water and Environment

Fox and co-authors admit the trial needs expansion. Without repetition, it's possible the alarmed section was less of a death trap for some unrelated reason. Nevertheless, the size of the decrease, and the fact that it applied to so many different types of animals, suggests the system accounted for at least some of the improvement.


Physical fences are not only more expensive than virtual ones but interfere with animals that need to cross roads to migrate or avoid interbreeding. The virtual fence lets animals cross as needed, as long as the road is quiet.

Many animals that have become endangered or extinct on the Australian mainland still thrive in Tasmania, partly because the island is free of foxes, something wildlife officials are desperate to preserve. However, one Fox may prove to be those endangered species' guardian.