It was snowy and cold last Saturday night in the wilds of the Allegheny National Forest, but the heat was on snowmobilers who were drinking and driving.

Five snowmobilers were cited for driving under the influence at a remote crossroads in southern Forest County, where law enforcement officials are trying to reign in such behavior in the national forest after two fatal snowmobile collisions and numerous accidents already this winter.

The DUI checkpoint along Wolf Run, east of Marienville, was the first in the national forest this winter but a U.S. Forest Service official said more are planned. Similar checkpoints have been held in previous years, but officials would not say when or how often.

Law enforcement officers from the forest service, Pennsylvania Game Commission and Forest County Sheriff's Department set up the checkpoint from 7 to 11 p.m. at the intersection of Lamonaville and Loleta roads. They stopped 49 snowmobiles and ordered breath tests for 17 drivers who were suspected of using alcohol.

Of the five drivers charged with DUI, two also were charged with trying to elude enforcement officers and two were charged with not having valid insurance. One operator was taken to the Clarion County Jail for violating conditions of probation.

Officers set up the checkpoint on a road that is jointly used by snowmobilers as well as drivers of cars and trucks and is part of the 120-mile snowmobile trail loop established by the forest service. Lamonaville Road, also known as Forest Road 130, was the site of the second fatal snowmobile accident last month; the other occurred in December.

Both accidents remain under investigation by state police.

"We've had snowmobile fatalities on the forest in the past and two on the loop this winter. In the past we've run patrols from vehicles and snowmobiles and this year decided to implement the checkpoint," said Capt. Steven Burd, of the forest service's law enforcement division.

"We think it was successful," he said. "Checkpoints have been shown to be effective for road vehicles, and to protect the lives of snowmobilers we think it is certainly appropriate."

Forest County Sheriff Robert Wolfgang said the checkpoint results show drinking while operating a snowmobile is a big problem in the national forest.

"Those DUIs -- five out of 49, more than 10 percent -- are pretty alarming," Sheriff Wolfgang said. "The snowmobiles operate on forest roads and town streets with other vehicles and I don't want my mom or dad, wife or kids run over by one."

Snowmobiling in the national forest is encouraged as a winter recreational pastime that attracts people from Pittsburgh and counties in Pennsylvania's northern tier, Ohio and New York, and produces welcome economic activity in nearby towns.

Although the vast majority of snowmobilers abide by prohibitions against alcohol consumption, the snowmobile loop, which circles through Forest, Elk, McKean and Warren counties, goes by or near a number of bars and restaurants.

"We have a long-standing problem on the ANF because the snowmobile system passes by a number of establishments that serve alcohol," said Karen Atwood, secretary of the Tionesta Valley Snowmobile Club.

She said the loop trail area around Marienville and between that town and Kellettville in Forest County is a known "hot spot" for reckless riding, speeding, and alcohol use by snowmobilers.Other known problem areas for snowmobile speeding and accidents are in McKean County, on the northeast side of the forest near Lantz Corners and around Kane, where residents have complained about speeding and rowdy behavior connected to a couple of bars.

"In fairness, many of the problems happen primarily on weekends when the out-of-towners come in from Ohio and Pittsburgh to snowmobile," said Ms. Atwood, who has been a state-certified snowmobile safety instructor since 1975.

"Unfortunately, many visiting snowmobilers brag about riding the loop in record time."

She said she and her husband, Ed, were eating in a bar/restaurant near Marienville several years ago and watched snowmobilers drink enough to cover the table with empty 16-ounce beer bottles.

"The fellow got up to leave and had to be helped into his snowmobile suit by his friends," she said. "He staggered out and climbed on his snowmobile and left Marienville. Too bad they didn't have a checkpoint waiting for him."

Federal and state laws are tougher on driving snowmobiles under the influence of alcohol than on driving cars and trucks. It's illegal to operate a snowmobile after drinking any alcohol -- a so-called "zero tolerance" policy.

Federal penalties for snowmobiling DUIs start at $375 for first-time offenders and can go as high as $5,000 and six months in jail. Additional penalties can include fees to impound snowmobiles involved, community service, alcohol counseling and suspension of drivers licenses.

Those charged at the checkpoint with driving under the influence -- a federal violation because the stop occurred on the national forest -- were: Ronald D. Eikey, 47, of Pittsburgh; Roy E. Davis, 43, of Oakdale; Gregory A. Thomas, 32, of Greenville, Mercer County; Barry A. Vandervort, 39, of Tionesta, Clarion County; and Kevin McFarland, 50, of Lucinda, Clarion County.

Each was fined $375. Mr. Vandervort and Mr. McFarland also were fined $175 for operating a snowmobile without valid insurance and $275 for attempting to elude a law enforcement officer.

"I think snowmobilers get a bad rap. I really don't think there's a drinking problem," said Mr. Thomas, who has been riding on forest trails for years and has a camp in the area. Before he was stopped at the DUI checkpoint, he said he'd been to the Kelly Hotel in Marienville where he had a big "Kellyburger" and two drinks.

"I was not intoxicated. If I'd had two drinks and been in a car, I wouldn't have got a DUI," he said, adding that two other drivers stopped at the checkpoint also had a couple of drinks with him but were not cited.

Mr. Thomas contended that most of the snowmobile accidents he knows about were caused by driver error rather than drunken driving.

"But I have nothing against it. Law enforcement was doing its job. There's zero tolerance and I don't have a problem with that," he said.

Ms. Atwood said many snowmobilers don't realize that cold weather and wind chill caused by the moving snowmobile exacerbate the effects of alcohol. They mistakenly think the cold will cancel out the alcohol they've consumed and sober them up.

She said snowmobile use requires a clear head and sharp reflexes to respond to hazards on snowmobile trail systems that can include fallen trees, heavy snow, protruding rocks, animals and darkness.

"There is no place for snowmobile use and alcohol, except after the keys are out of the sled's ignition and the person is no longer riding," Ms. Atwood said. "Alcohol dulls the senses and releases inhibitions, making people think they are capable of much more than they can do and doing it at a greater speed than is prudent."