Somerset is introducing new acoustic devices which emit high frequency sound to warn deer not to go into the road.
The equipment - triggered by car headlights - works with an interactive sign encouraging drivers to slow down.
The idea is to make the county's roads safer for deer and motorists during the dark winter months.
The scheme will be piloted on the A39 from November between Nether Stowey and Holford and between Kilve and East Quantoxhead.
Each year around 20 deer are killed on this stretch of road.
"Accidents are often caused by a driver swerving to avoid a deer and veering in to the path of an on-coming vehicle, causing a major collision which can result in serious injury and even death," said Tony Shire, Somerset County Council.
Somerset Highways has been working with Dr Jochen Langbein who oversees the National Deer Collisions Project on behalf of the Deer Initiative.
Dr Langbein said car headlights would activate the warning devices and emit a high pitched whistle which can be heard above the noise of the traffic.
"These devices, installed at 50m intervals along the stretch of road, will only be operational at dusk and in the dark so that the deer do not become over-familiar with the noise.
"It's likely that the sound of traffic has become a background noise to the deer and that they cannot judge the direction and speed of its approach.
"We hope the whistle will startle them and stop them in their tracks while the vehicle passes by safely."