Can a monster traffic jam spanning dozens of miles and leaving drivers stuck for days really disappear overnight?

For days, Chinese and foreign media have issued reports explaining how thousands of vehicles were trapped in an epic traffic jam stretching for more than 100 kilometres (60 miles) on a highway leading to China's capital Beijing.

The bottleneck on the Beijing-Tibet expressway, which began on August 14 due to a spike in traffic by cargo-bearing heavy trucks and was compounded by road maintenance works... seems to have vanished.

A team of AFP reporters drove 260 kilometres Wednesday along the highway out of Beijing, through the northern province of Hebei and into Inner Mongolia -- and did not encounter anything but intermittent traffic jams at toll booths.

Hundreds of trucks were on the road to Beijing, packed with everything from produce to live goats -- but the traffic was moving.

"The situation has gotten much better recently. I don't know why," a female gas station attendant in Huailai county, roughly halfway from the capital to Xinghe county in Inner Mongolia, told AFP.

Officials at the Beijing traffic management bureau were not immediately available for comment.

The state-run Global Times said Monday the jam had spawned a mini-economy, with local merchants capitalising on the stranded drivers' predicament by selling them water and food at inflated prices.

The stretch of highway has become increasingly prone to massive tailbacks as the capital of more than 20 million people sucks in huge shipments of goods.

Traffic slowed to a snail's pace in June and July for nearly a month, according to earlier press reports.

China has embarked in recent years on a huge expansion of its national road system but traffic periodically overwhelms the grid.

According to government data, Beijing is on track to have five million cars on its roads by year's end. The four million mark was passed in December.

The head of the Beijing Transportation Research Centre, Guo Jifu, warned this week that traffic in the capital could slow to under 15 kilometres an hour on average if further measures were not taken to limit the number of cars.