SPRINGFIELD, Mass. – At night on a dark country road all that the headlights catch are the shadowy legs the size of tree trunks rising out of the pavement.

Standing 6 feet at the shoulder, weighing up to 1,000 pounds, with massive antlers more than 5 feet across, moose tower over automobiles and have no fear of them.

Increasingly the undisputed giants of the northern forest are tangling with traffic as they expand south. Massachusetts motorists hit 52 moose last year, a more than sixfold increase in four years.

For decades road officials have relied on warning signs and publicity campaigns such as New Hampshire’s “Brake for Moose” bumper stickers.

But now some traffic engineers around the country are experimenting with redesigning roads to accommodate wandering wildlife and using high-tech laser and infrared devices, developed for space exploration and anti-missile systems, to warn motorists when a moose wanders into the road.

“We’re investigating ways to manipulate the drivers and also ways to manipulate the animals,” said John Perry, a biologist with the Maine Department of Transportation. “And when moose are involved, it might be easier to manipulate the driver.”

Moose, unlike deer and bear, are reluctant to use some of the new protective alternatives such as animal underpasses fashioned out of giant culverts, said Bill Ruediger, recently retired head of the U.S. Forest Service’s highway ecology program.

In a typical collision, the car hits the animal’s legs, causing the moose to crash down through the windshield, crushing the roof and landing in the passenger compartment.

One in every 75 people who hit a moose is killed compared with one in 5,000 who hit a deer, said Bill Woytek, moose and deer project leader for the Massachusetts Division of Fisheries and Wildlife.

And as the snowdrifts recede and the first green shoots begin appearing along the sun-warmed pavement of northern roads, biologists are warning motorists to be on the lookout for noshing moose. The animals also are drawn to the road salt that collects on the pavement and in the small wetlands and hollows along the roads, Perry said. “We call them ‘moose wallows.”‘

Most collisions happen in the spring, when yearling moose head out on their own, or during the fall mating season. A bull moose in pursuit of his lady love is not going to pause to let a minivan pass.

And young moose have a tendency to wander into suburban swimming pools and city downtowns. A few years ago, one even turned up in Boston’s bustling financial district.

It is not easy to keep a moose off the road. Fences need to be at least 8 feet high, and specially designed animal overpasses, more than 100 feet wide, are very costly.

Traditional warning signs tend to get ignored after a few months or years, the engineers said. Or just disappear.

“People steal them,” Woytek said. “And they don’t do any good in a dorm room.”

But drivers will slow down when confronted with a flashing sign that a moose is in the road, said Marcel Huijser of the Western Transportation Institute at Montana State University, which is overseeing a joint project by 12 states and the federal government on the use of animal sensor systems.

None of the New England states has experimented with an animal sensor system, but Maine is trying to keep and hold motorists’ interest with warning signs that light up when a car passes.

But Woytek and other state biologists are tracking some of Massachusetts’ small herd of about 1,000 moose with radio collars to see if the more suburban moose have developed different habits and movements than their counterparts in the north woods.

Maine is also trying some low-tech strategies, including lining the shoulders of some roads with loose rock. The hope is the uncertain footing will prompt moose to stroll slowly, rather than sprint into the road, giving drivers more time to swerve.

The sensors have been tried in 29 locations around the world, including nine in the United States and one in Canada, since 1993 when the first was installed in Switzerland, Huijser said. Engineers on the Swiss system say they have reduced by 80 percent crashes involving wild boar and other large animals.

The sensors use a variety of devices, including infrared beams, microwave radio and vibrations in the soil, Huijser said, but all basically send a signal that lights up a sign when an animal crosses a beam or other sensing device along the road.

Two recent experiments include a mile-long system installed in Yellowstone Park last November aimed at detecting moose, bear and other large animals, and another on six segments of the Indiana Toll Road, each a mile long, he said, but neither has been installed long enough to really test its effectiveness.

“We’re really looking into the future,” said Samuel Wolfe, project director for the Indiana Toll Road. “We aren’t there yet, but a time will come when high-tech automobiles will be able to respond to high-tech animal sensors.”