It was built at massive expense as a symbol of success for the new Afghanistan, but instead the Kabul-Kandahar road has become a highway of death that shows what has gone wrong.
It is supposed to be a symbol of progress in the new Afghanistan, but as Nato prepares to withdraw its combat troops over the next two years the main road between the country's two largest cities has become instead a symbol of what has gone wrong.
Rather than providing a secure transport link between the Afghan capital, Kabul, and the country's second city, Kandahar, Highway One has become a highway of death.
Opened to great fanfare in 2003, it was hailed as a key element in rebuilding the economic infrastructure of the war-shattered nation. But today its once-pristine asphalt has become as scarred as the country's hopes for peace - a bomb-cratered, 300-mile long shooting gallery littered with the wrecks of vehicles attacked by Taliban insurgents.
Thousands of hard-up Afghans still have no choice but to brave its passage every day by car and bus, but for westerners - and anyone else who can afford to avoid it by paying out for a commercial flight ticket - the road is effectively a no-go zone. As well as the threat of shootings, hold-ups and roadside bombs, there is the risk of kidnap: anyone with money, and especially a foreigner, is a tempting target.
For that reason I had never expected to travel Highway One myself - until The Sunday Telegraph was invited to join an armed government convoy heading down the highway to Ghazni province, 100 miles away.The arrangements were made by an Afghan government minister keen for reporters to see how locals in the area had turned against the Taliban. Photographer Jason Howe and I were escorted by heavily-armed Afghan special forces commandos as we prepared to travel through insurgent country in a large white 4x4 that obviously belonged to the disliked Kabul government.
As our convoy formed up on the south western outskirts of Kabul, it was clear that I was not the only one feeling apprehensive.
"I am going to be truthful: we don't know what's going to happen and there are some very dangerous stretches of road," said Idris, the driver of the Toyota Land Cruiser which was to carry me.
Idris, a curly-haired man in his thirties, said he had personally been attacked five times on the road, including one incident where a guard in his car had been shot dead.
It was not the kind of reassurance I had hoped for. As we waited for our convoy to assemble, he adjusted a pistol in his shoulder holster and cocked the AK-47 rifle nestling by his right knee in the foot well. "If we get attacked though, we'll fight back," he said.
Once complete, our convoy consisted of two Land Cruisers and six pick-up trucks full of commandoes, armed with an assortment of machine guns and rocket-propelled grenade launchers.
With drivers scanning the roadsides and commandos watching the hills, we set off. The road snaking through Wardak, Ghazni and Zabul provinces is a critical artery binding the capital to the south of the country. Linking the seat of government with Kandahar - a city long regarded as the spiritual birthplace of the Taliban movement - it passes through villages, mountains and plains where President Hamid Karzai's administration struggles to exert influence.
It is also the route taken by vast caravans of Afghan civilian supply lorries ferrying food, fuel and equipment to Nato and Afghan military bases across the south.
The road's importance has not been lost on the Taliban, and it has been under relentless attack for at least five years. Statistics for violence on the road are sobering. By the middle of August, there had been 190 bomb attacks along the road in 2012 alone. On top of that, there had been another 284 shooting attacks, or nearly one for every mile of road.
No proper figures for casualties are available, but the best estimate from police officials is that several dozen people have been killed or wounded travelling the highway this year, and hundreds over the past few years.
Our convoy did not have to venture far from Kabul before signs of this bitter struggle were all too clear.
As the road passes through picturesque villages and farmland, it is lined by hundreds of filled craters left by years of roadside bombs, many of them detonated by remote control.
Some are several yards across, and at times they are so close together the traffic must slalom from one side of the road to the other.
American soldiers say they have uncovered devices made of 250lbs of home-made explosive - more than enough to obliterate our vehicles and even flip the hulking armoured trucks used by US troops.
The blast craters have created a cottage industry of road menders who fill them with rubble. Unfortunately, these rubble-filled craters then become prime spots to plant more bombs.
Idris' answer to that threat was speed. Each time a patch of rubble loomed, he floored the accelerator and we held our breath as we bumped over it, or screeched around its rim - at one point nearly pitching my photographer colleague from the back of his pickup truck.
"You have to get across it fast if there's a bomb," Idris explained. "Before the trigger man has time to press the button."
At one point we had to leave the road entirely to skirt an American military convoy which was trying to salvage a transporter trailer mangled by a blast.
Yet the road is chaotically far from deserted. Minibuses, saloon cars and coaches all jostle for space with the convoys of fuel tankers and container lorries carrying military supplies.
To try to reduce the risk of attack, many vehciles make the trip on special "convoy days", when the road is flooded with Afghan security guards to try to keep Taliban at bay while trucks pass.
Speeding up and down while armed to the teeth, the wild-looking guards are fearsome, but cannot completely prevent the onslaught of attacks.
As the road passed through its most dangerous stretch, south of the town of Sydabad, the carcasses of burnt-out tankers lined the sides of the road and twice blocked it.
This is Taliban heartland: an area where, try as they may, Nato forces have been unable to dislodge the insurgents who inhabit many of the towns and villages near to - and in some cases along - the road.
Scorched patches of asphalt showed where other lorries had been incinerated. The commandoes became visibly more tense, peering through their gun sights.
It is also this area that most Afghan travellers fear the most. For them, the trip has the added risk of Taliban checkpoints where traffic is halted and passengers are scrutinised for links to the government, or foreign organisations. A scrap of paper from a government document, or a suspicious number on a mobile phone, may be all that is required to merit a summary roadside execution, according to those who travel the route regularly.
Passengers claim that frequently the insurgents appear to have been tipped off about who is heading their way, probably by spies in Kabul's bus stations.
The risks meant we were unable to stop and talk to our fellow travellers. But days earlier, I had heard hair-raising tales from the bus drivers who ply the route each day from Kabul's Kandahar bus station.
Speaking outside his office, Hakimullah Khan, told me during his own eight-year driving career he has been stopped 20 times by Taliban checkpoints that spring up in the middle of the night.
Most recently, in April, the first sign of trouble he saw was when his headlights fixed on the insurgents' gun barrels, and by then it was too late to do anything. He had no choice but to bring his creaking bus to a halt before the half dozen gunmen, as they raised their assault rifles level with his windscreen.
On this occasion, after a cursory search, he and his passengers were allowed on their way - but as Mr Khan knows all too well, there is always a next time. "The road is very dangerous," he said. "But it is my job, what can I do?"
Thankfully our own trip passed off without any attack. But the scenes we saw along Highway One were a terrifying glimpse of the gauntlet run daily by ordinary Afghans. They show why the road remains a major headache for coalition forces as they try to forge an exit strategy - and are also a glaring sign of the weakness of Mr Karzai's government.
The counterinsurgency doctrine espoused by Nato commanders prizes freedom of movement for the local populace, yet after 10 years of international military help, the country's main artery remains too perilous for many to use. And soon its security will be entirely in Afghan army hands.
"We have to secure that road before we leave," one Nato general in Kabul lamented earlier this year. From what I saw during the journey along Highway One, they still have a long way to go.