Drivers are being asked to take special care on rural roads this month - the peak time for badgers to be on the move as the breeding season approaches and as the young start to leave their families.
Experts estimate that vehicles kill 50,000 of the animals each year, particularly when they emerge at night in search of food.
Jack Reedy, a director of the Badger Trust, said: "Traffic is the number one threat to Britain's badgers and new roads can divide territories and result in more deaths as badgers continue along their traditional routes.
"This carnage represents something like a fifth of the estimated badger population."
Vehicle use has risen by more than 80 per cent since 1980. There are now more than 30 million cars on our roadsand motorways carry up to 200,000 vehicles a day.
Mr Reedy said: "Over the past 20 years the number of cars using country roads at night is vastly more than it was before. Motorists need to be particularly careful and go around corners ready to brake.
"If a vehicle is coming the other way you can see its headlights, but animals don't have headlights."
Tony Sangwine, principal adviser for biodiversity and landscape for the Highways Agency, said: "Badgers are being killed on our roads on a daily basis and it is a big problem for local highway authorities."
The Highways Agency now considers badger safety when building new roads. As part of the £175m upgrade of the main route between England and Scotland announced in July, badger-proof fencing and tunnels are being created to give wildlife a safe route under the motorway.
Twelve such "badger mitigation" schemes are in different stages of development around the country and will join the 250 badger tunnels and some 200km of fencing already along some of Britain's roads.
But the Badger Trust says more needs to be done, particularly when it comes to the maintenance of existing safeguards. The charity is calling for a co-ordinated policy and greater funding to protect the animals from traffic.
Britain's badgers are not the only victims. Altogether, with estimates of 75,000 foxes and 40,000 deer, some 165,000 animals are killed by motorists each year. Conservationists claim badgers and other animals seen dead by the roadside are just the tip of the iceberg, with as many dragging themselves away to die.
But because the cost of safeguarding badgers on a single stretch of road can be up to £100,000, Mr Sangwine says the Government cannot spend disproportionate amounts of money on protecting wildlife.
"Boring badger tunnels under existing roads would not make economic sense," he said. "You would be spending millions of pounds to provide safe crossing places for badgers. We have to accept that it is a fact of life that animals will be killed on roads and there is no surefire way of dealing with that problem in totality."
The human threat to badgers does not only come from traffic.
The National Farmers' Union is repeatedly calling for the animals to be culled. Were those appeals to be heeded, the species could be wiped out from vast swathes of the British countryside.
The debate over bovine tuberculosis is continuing, with pro-badger groups denying accusations by farmers that badgers are the reservoir for a disease that can kill cattle.Reuse content