After 37 years as a long-distance cargo driver, Sultan Mohammed is intimately familiar with the hazards of navigating the 450-mile stretch of road between the cities of Kabul and Kandahar.

Bombed by Russian forces in the 1980s, rocketed by warring Islamic factions in the 1990s and neglected by every government in the past two decades, the once-modern highway has gradually deteriorated into a cratered obstacle course, and the journey into a 14-hour crawl.

So this morning, Mohammed was both incredulous and delighted when Afghan and foreign officials gathered near this village beside the road 25 miles south of Kabul, the capital, to inaugurate a long-awaited, $250 million international aid project to rebuild the country's main highway.

"This is like reaching out a hand to a drowning man," said Mohammed, who was waiting by the roadside with a dozen other truckers as soldiers cleared the way for a VIP motorcade to the spot where the short paved portion of the highway ends and the endless, sandy slalom to Kandahar begins.

President Hamid Karzai, flown by helicopter to the site for a brief roadside ceremony under a chilly drizzle, was equally dramatic in his assessment of the project's significance for Afghanistan, a country that has been fractured and bankrupted by 23 years of war and turmoil.

"These roads are the veins of Afghanistan, and its blood flows along them," Karzai said. Once the roads are rebuilt, he predicted, they will become the "backbone" of a prosperous nation and a new commercial link between Central and West Asia.

The Kabul-Kandahar road, which forks into other highways leading to Pakistan and Iran, was built with U.S. and Soviet assistance in the early 1960s, and it soon became a major regional trade route, with thousands of trucks a week hauling tires, appliances and consumer goods from one end to the other.

Because of its strategic significance, the highway was also a natural target for military attack, first during the Soviet occupation of the 1980s and then during the civil strife and anti-Taliban fighting of the 1990s. Neglected for years, it became little more than a desert track in some spots and an axle-killing roller coaster in others.

Karzai, who took office last December, has said repeatedly that repairing the country's intercity roads was one of his top priorities. For many months, however, not a shovel was turned as the plans bogged down in delays and disputes among foreign donors, multilateral lenders and Afghan agencies.

Karzai refrained from criticism in his brief, rain-drenched speech, saying, "We are only grateful today." But the U.S. ambassador, Robert P. Finn, hinted at the problems in his address, urging Afghan and foreign governments and donors to "see each other as partners rather than adversaries," and to "build each other up rather than tearing each other down."

The U.S. government is providing $80 million for the highway reconstruction, its largest single aid project in Afghanistan since the fall of the Taliban last year. Japan and Saudi Arabia are providing $50 million each. The project is expected to take three years and provide work for thousands of Afghans.

Construction is to begin immediately, but officials said that when winter sets in, work will shift to a second stage of the project, along the 400-mile highway between Kandahar and Herat in western Afghanistan, where the climate is warmer.

Finn described the project as a "tremendous tangible investment" by the foreign community, saying it would "draw the Afghan family closer together," boost trade and improve access to health care and education for inhabitants of the region. "It could mean the difference between life and death," he said.

Afghan and foreign officials said they are concerned about security for the project, with portions of both the Kabul-Kandahar and Kandahar-Herat segments plagued by banditry and regional armed conflicts. Security was especially heavy for today's ceremony, with hundreds of soldiers guarding the route and all traffic from Kabul halted.

The presence of land-mine-clearing teams, already busy at the site where the project will begin, was also a dramatic reminder of the hazards of working in Afghanistan. Using metal detectors and sniffer dogs, the teams are clearing a 12-foot path on both sides of the road, and they will precede the repair crews as they advance.

For residents and drivers, who were herded away from the ceremony by armed Afghan and U.S. troops, the brief indignity hardly mattered. Everyone knew that when Karzai and other officials turned over symbolic shovelfuls of earth onto the highway, it signaled the beginning of a resurrection.

Several older men said they had been on crews that constructed the original Kabul-Kandahar highway four decades ago. After so many years of destruction and neglect, they said, they had given up hope that it would ever be restored.

"The road was getting worse day by day. The reconstruction of it makes us hopeful for the reconstruction of the whole country," said Sadruddin, the owner of a highway rest stop and cafe in Durrani. "People never thought this would start. It's easy to make promises and propaganda. But when you see something put into practice, you know it is real."

President Hamid Karzai, left, prays with U.S. Ambassador Robert P. Finn, center, and Japanese Ambassador Kinichi Komano during a ceremony marking the start of the project. A vehicle hauling goods passes a mosque at sunset on the road between Kabul and Kandahar, a 450-mile stretch that takes 14 hours to traverse.