Doesn't work Roy. The Deer Comission closed the A9 for around 8 hrs last year to carry out a cull on the deer that congregrate close to the roadside. Their theory was that deer are habitual animals and by eliminating them they would prevent collisions with motorists and deer getting killed.
It turned out to be a complete waste of time and money. Not to mention the disruption to motorists (and loss of income to local services) and the inconvenience caused to local people, supplies and even emergency service vehicles.
UK deer population has gown significantly in the last 30 years to more than a million and set to double over the next 10. The reason is attributed to increased woodlands, milder winters and a lack of natural predators.
It's in the most heavilly populated areas in England that the problem is most acute. 120 collisions a year are recorded in Ashbridge, Hertfordshire and 300 year in Hampshire. There is also significant problems from foxes, pheasants, badgers, horses, squirrels and even sheep recorded all over the UK.
A few years back I come across a bolted horse running free on the back roads outside Dunkeld and I've come upon a whole herd of roe deer on the same road.

A horse can weigh up to a ton and a red deer around 25 stone so a collision is going to be serious.
The most significant solutions seem to be underpasses, bridging methods (used for squirrels in many areas) and even a series of rumble strips used to create noise that will repel animals as vehicles run over them. Rumble strips have been used succesfully on the B1106 in Suffolk for example.
Ultrasonic devices. Such as those used in the USA and Canada which are fitted to the front of vehicles have proven to be unsuccessful in trials in the UK.
In Germany they have found 'light fences' to be extremely effective. These are errected along known strike routes and use the lights of cars to reflect a trail of alternating light along the length of the fence. This also sets of an audible warning. Both the light and sound startles the animal and prevents them crossing the road at that point.
These 'light fences' have recently been introduced in East Anglia, Hertforshire and Somerset but one would imagine they are only effective at night.
