IN THE SALANG TUNNEL, Afghanistan - It was built to be a lifeline, a marvel of modern engineering that would reduce the risk of traveling through the towering Hindu Kush mountains.
Instead, the Salang Tunnel is the most dangerous obstacle each day for the hundreds of Afghans who travel the main highway connecting Kabul with northern Afghanistan and the only overland route connecting north and south that is open all winter.
In recent weeks, 40 people have perished while trying to navigate the bombed-out remnants of the 1.6-mile tunnel, making the Salang, at 11,034 feet the highest tunnel in the world, undoubtedly one of the deadliest.
Built in 1964 by Soviet engineers, the tunnel was ordered destroyed in 1996 by the Northern Alliance's military commander at the time, Ahmad Shah Masood, who wanted to prevent Taliban troops from crossing into his Panjshir Valley stronghold.
When the Taliban collapsed last month, the Salang reopened for traffic. But the destruction Masood wrought and the land mines the Taliban left behind have rendered the route as treacherous as the mountains the tunnel was meant to tame.
The paved road leading from the main northern city of Mazar-e Sharif to Kabul ends a mile from the tunnel entrance. The route continues upward along snowy paths and colonnaded galleries blasted from canyon walls, the latter another engineering marvel that once protected vehicles from boulders and avalanches.
There are no cars and trucks now, just sullen travelers on foot carrying heavy loads while picking their way along narrow footpaths buffeted by the winds whistling out of the Hindu Kush. People with similarly large loads going in the other direction jostle for position - no one wants to be the closest to the edge. But neither does anyone want to veer too far from the edge for fear of land mines.
The worst stretch begins at the northern entrance. Travelers clamber uphill over the ice-covered wreckage and find themselves in a cavern of frigid, smoky darkness. The tunnel floor is strewn with jagged and rusty shrapnel, twisted steel girders, severed electrical cables and broken concrete slabs. These hazards are visible only in the pale flashlight beams that barely illuminate the foul-smelling gloom.
Some travelers - traders transporting goods to and from markets and porters for hire - are accustomed to the route and quickly make it through. But some struggle - families carrying small children, refugees returning to their homes after the war, shepherds herding flocks of sheep.
It is easy to fall. The darkness conceals icy patches, and the bitter cold and thin air make it difficult for travelers not used to exerting themselves at high altitude to get enough oxygen.
The tunnel has been a killer. In 1982, a gas tanker exploded nearby while a column of Soviet tanks was traveling through the Salang, killing 179 troops and a large number of Afghan civilians.
The Soviets abandoned their decade-long occupation of Afghanistan seven years later, largely because of the efforts of Masood, who blew up bridges and supply routes to make his stronghold in the Panjshir inaccessible and to make it easier for him to harass his foes.
Dozens of abandoned Soviet tanks strewn along the side of the road to Salang bear testimony to the effectiveness of his strategy.
When the Taliban swept through most of Afghanistan by the end of 1996, Masood again used his favorite tactic, and this time he blew up the tunnel, too. The blown-up bridges were easy to replace with makeshift spans made from the carcasses of Soviet tanks. But the tunnel has been harder to fix.
Jalaladin, a Northern Alliance commander in Dushi, a town 10 miles north of the tunnel, was there when Masood blew up the tunnel. Jalaladin led his 200 men against the Taliban for five years so that the tunnel could be reopened.
People here depend on the tunnel to make a living, he said, by selling the goods traders carry from Kabul, 60 miles south of Salang, or by offering food and lodging to travelers.
Until the Taliban fell, the only way from here to northern Afghanistan was a tortuous mountain pass that cuts through the alliance-controlled Panjshir Valley. But that road closes to vehicles in late October.
"All of Afghanistan suffers because the tunnel is closed" to vehicles, Jalaladin said.