They've tried reflectors. They've tried lighted crosswalks. They've even tried constructing deer overpasses and underpasses.

		Graphic: Fatalities from deer/car collisions in Pennsylvania

But no matter what wildlife experts do, they've been unable to find an effective, affordable way to keep deer off highways.

Each year, the Pennsylvania Department of Transportation and the state Game Commission spend more than $1 million to collect 35,000 deer carcasses from roads, and officials estimate that at least 25,000 more are hit and die in the woods or on private roads.

Last year, those thousands of crashes resulted in the deaths of 14 motorists in Pennsylvania.

In 2002, there were more than 1.5 million deer-vehicle crashes in the United States that left 150 people dead and caused at least $1.1 billion in damage, according to the Insurance Institute for Highway Safety.

As rutting season hits its peak -- it runs through mid-December -- and when rifle-hunting season begins next week, even more deer will be on the run and crossing in front of traffic.

Officials warn that motorists should slow down, be alert and be aware that if one deer is spotted, there are almost certainly more nearby. Does often travel in groups of three to five.

For decades, researchers have tried to find reliable ways to keep deer off roads. Still, the most promising methods are reducing the deer population and building fences at least 8 feet tall.

"With the amount of roads, it's really not a viable option," PennDOT spokesman Steve Chizmar said of expensive fencing.

Remedies such as deer crosswalks and underpasses can be successful for mule deer out West that have a fixed migration pattern, but not for white-tail deer in the East, said Allan Williams, chief scientist for the Insurance Institute for Highway Safety.

PennDOT has tried several things to keep motorists safe from deer, including putting up more signs warning of deer crossings and keeping vegetation trimmed back from roadways.

"These static signs that are up there -- 'Watch for deer next 25 miles' -- they don't exactly work because people don't pay attention to them," Williams said.

This year, the state is testing a microwave-based deer-detection system. It's being installed on a stretch of Route 322 in Juniata County that records about 50 deer-vehicle crashes a year, Chizmar said.

The system, when it is operational, will include 18 sensors running parallel to a half-mile segment of the highway.

When a deer breaks the invisible microwave beam from a sensor, it triggers flashing yellow lights on a deer-warning sign. Motorists then will know to slow down even more.

The system costs about $100,000, Chizmar said, and it's also being tested as an infrared system in Montana.

"I think that's one of the most promising techniques out there," Williams said.

Many other methods have been studied; some work, some do not.

Quick and easy solutions, such as deer whistles that are placed on cars and emit ultrasonic noise, have been shown to be ineffective.

The most agreed-upon method is reducing the size of the deer herd.

The white-tail deer population across the United States dropped below 2 million by 1900 because of year-round hunting, no restrictions on how many animals could be taken, and changes in deer habitat, according to Paul Curtis, a wildlife specialist in New York.

But wildlife experts set out to grow the herd, creating restricted hunting seasons and teaching hunters not to shoot doe. Since then, the population has exploded.

According to the Insurance Institute for Highway Safety, the herd nationwide is now estimated at between 25 million and 30 million animals. About 1.4 million of those are in Pennsylvania.

Now, contemporary experts are reversing themselves again, encouraging hunters to shoot antlerless deer, said Gary San Julian, a professor of wildlife resources at Penn State University.

It's taking a long time to get the new message across, he said, primarily because of the bragging rights associated with taking bucks with large antlers.

"It's a trophy," he said. "Doe has always been looked at as a consolation prize."

To try to bring the population under control -- and reduce vehicle accidents -- hunters must harvest about 50 percent of the state's deer each year.

Hunters took 464,890 deer last year, just a third of the herd.

"Ultimately, we want to bring the deer herd in balance with the habitat."

Research notwithstanding, many fatalities in vehicle-animal could be prevented, according to the Insurance Institute for Highway Safety.

A study of 147 fatal crashes between 2000 and 2002 showed that 60 percent of people killed in vehicles were not wearing their seat belts, and 65 percent of people killed riding motorcycles were not wearing helmets.

In most of the fatal accidents, it was not the collision with the animal that killed people, but the aftermath.

In the motorcycle accidents studied, often the bike would strike an animal, throwing the rider off. In many of the car accidents, vehicles went off the road and struck another object.

Most of the accidents occurred in rural areas, on roads with a speed limit of 55 mph or greater, and at night.

Between 1993 and 2003, 1,458 people were killed nationwide in vehicle-animal crashes.

Here are some ways to avoid serious vehicle-animal crashes:

Drive slowly and be more alert;

wear seat belts and motorcycle helmets;

drive with high beams on whenever possible;

don't swerve to avoid an animal;

if you see one deer, there are likely to be more;

if there's a deer in the roadway, honk the horn at it to try to get it to move;

use flashers and flash headlights at oncoming traffic to warn them of deer in the area.