When the treacherous crossing between Chile and Argentina is shut down because of snowstorms, as many as 5,000 trucks can become stranded.

PASO LOS LIBERTADORES, on the Chile-Argentina border (By Larry Rohter, NYTimes) August 8, 2006 — It is the dead of winter in the Southern Hemisphere, and everyone in this part of the world knows what that means. Along with snowstorms, ice and glacial winds, there are sure to be thousands of trucks and cars stranded for days here at the choke point of commerce in South America, 12,671 feet up in the Andes.

That has been the case again this winter. The majestic, snow-capped Andes run the full length of the border between Argentina and Chile, but it is on the road from Santiago to Mendoza, here where the Christ the Redeemer Tunnel cuts through the cordillera, that the bulk of the road traffic between the countries is concentrated — and confusion and privation are most likely to occur.

“This is the most important cargo point on the entire continent, but we are subject to the vagaries of the weather,” said Juan Abarca Cordero, the Chilean director of the busy border complex here. “When the condors fly down from the heights to seek shelter and the fog closes in on the peaks, you can be certain that a bad storm is on the way and you are going to have to close the road.”

Less than a mile below the crossing is Portillo, one of South America’s fanciest ski resorts, where some rooms run more than $500 a night. As the highway zigs and zags toward the summit, it passes several times under chairlifts that transport skiers from the slopes to the warmth of their hotel at day’s end.

Truckers, though, pride themselves on their toughness, and in any case cannot afford to stay at the resort. Every year a few of them die of exposure or heart attacks attributed to below-freezing temperatures, the stress of driving the route or being stuck for days at truck “patios” on both sides of the border.

The terrain along the route is anything but hospitable. Aconcagua, which at an estimated 22,840 feet is the highest mountain peak in the world outside the Himalayas, lies just to the northeast, and as the road winds its way to this border post, there are precipitous drop-offs to gorges and canyons below.

And when the crossing is closed because of snowstorms, as it was for more than a week in late July, as many as 5,000 trucks can back up on the frontier, waiting for the weather to clear. Along a roadside some 40 miles from the border, for example, a group of Brazilian truck drivers, some first-timers clad in shorts, had been stranded for 12 days and were fretting about the cold and the money and time they were losing.

While they wait, the truckers sleep in the cabins of their trucks, many of which are equipped with simple cooking gear. They go days without a bath, and have to use the side of the road for their physical necessities. To keep warm during the day, they sip yerba maté, a bitter, caffeinated herbal tea widely consumed in the southern half of South America, and at night they resort to bonfires.

“Every time you cross the cordillera, it’s a new adventure,” said Vilmar Rocha, 40, a Brazilian and 22-year veteran of the route. “But this time of year, it is also a suffering. You’re cold, you’re tired, you’re hungry, you smell of diesel smoke and you’d give anything for a bar of soap, a warm shower and a clean bed.”

Truck traffic, cheaper than sea or air shipments, has increased here by an average of 10 percent a year over the past decade, Mr. Abarca said, with Brazil, the region’s largest economy, accounting for nearly half the movement. On a busy day, as many as 1,200 trucks, many more than 60 feet long, pass through here.

For years, both Argentina and Chile have sought alternatives to the treacherous roadway, which narrows to only two lanes in many of its most mountainous stretches. There has been talk, for instance, of spending $1.5 billion or more to build a longer tunnel to accommodate the mounting traffic, revamping a railway closed in 1979 and even installing heating coils in the roadbed, as some nations have done in the Alps.

On average, bad weather forces this border crossing to close for 40 days in the winter months between May and September. Last year, though, that figure rose to 46 days because of 48 feet of snowfall and an avalanche that buried a dozen trucks, destroying some and sweeping others over a cliff.

Remarkably, no one was killed, though the drivers know the threat of death is always there. “Never lose your fear of the cordillera, that’s what I’ve learned,” said Adriano Plácido, a 24-year-old Brazilian who said he had made the crossing 20 times since becoming a driver a little over a year ago. “The fear keeps you alert and focused, with your adrenaline flowing. The minute you lose that fear and start to relax, you run the risk of losing your life.”

July may be the worst month on the route, not just because of the weather but because schools are closed for winter vacation and families are on the move. With the strong Chilean peso and a booming Argentine economy, tourism is thriving, which means plenty of inexperienced drivers on the road.

“They see something interesting and decide to stop to take a picture,” complained José Luis Carrizo, an Argentine truck driver from Buenos Aires. “They forget there are three trucks right in back of them, riding their brakes and dragging 50 tons of cargo behind.”

But a few truckers also bring along their wives and children during the winter school break. Marina Marques, 35, said that because she and her two sons, ages 11 and 8, had never seen snow, they decided to accompany her husband, Dirceu, 37, on one of his runs across the Andes from their home in southern Brazil.

Ms. Marques said that by coming along she had gained new respect for her husband’s work. But she also said she couldn’t imagine returning.

“I don’t ever want to see snow or ice again,” she said. “When I get home, I’m even going to sell my refrigerator.”