The thrum of motorcycles echoes over a Chinese mountain road, where hundreds of thousands are shunning public transport to take the highway home during the world's largest annual human migration.

China's 245 million migrant workers -- twice the entire population of Japan -- generally have to travel on jam-packed trains or buses to get to their hometown to see their families for the Lunar New Year.

But this year more than 600,000 are expected to ride by motorcycle, according to state-run media, making gruelling journeys of several hundred kilometres for the country's biggest festival, while a hardened few are even cycling.

"I'm excited, I want to get back home as soon as possible," said Mo Renshuang, a shoe factory worker who stopped to stretch his legs at a rest stop several hours into his 700 kilometre (430 mile) trip.

He was heading from Guangdong, one of China's richest provinces, to Guangxi -- one of its poorest regions.

Mo has not seen his two children for half a year, he said, and had strapped a supermarket trolley to the back of his motorbike containing a suitcase, two toy cars, a toy horse and a pair of blue children's boots.

"Pretty creative, right?" he said.

More than 158,000 bikers have passed the rest stop in the last fortnight, police estimate, as riders sharing the same hometown drive together in convoys and stop for free cups of porridge.

"There are no buses to my village," said Lu Liangquan, 50, one of more than 3,000 to pass by on Wednesday morning, who had balanced a cardboard box of fruit on his bike.

"Also, if you ride a motorbike you can carry on using it when you get home."

The two-wheeled journeys reflect huge growth in motorcycle ownership in China, which for years has been both the world's largest producer and consumer of the vehicles. More than 23 million were sold in 2013 according to industry figures.

They have proved popular with workers migrating from China's poor countryside to its coastal manufacturing heartlands, who have seen wages rise by up to 10 percent annually in recent years but often still cannot afford a car.

China's rail and bus network is stretched to breaking point over the New Year, which authorities say will see 3.6 billion journeys, leaving many struggling to buy train tickets.

"Travelling by motorbike is quicker than taking the bus," said gardener Huang Zilin, 40, who pulled into the rest stop on a red Yamaha with his wife.

"We set off at four in the morning, and my legs and feet ache," he added.

Pedal power

The riders -- who travel on small roads to avoid heavy tolls, and wrap their feet in plastic bags to protect against cold and dirt -- have been dubbed the "bike army" by the Chinese press.

Their steeds are an array of bargain-priced Chinese-branded vehicles, alongside Japanese Hondas and Suzukis.

But a handful of others were more ambitious and used pedal power alone.

"I have this returning home mood so I can stay awake. It's excitement I suppose," said Wang Zhekun, 30, an office worker for an autoparts company, who said he had cycled through the night on his red "Forever" mountain bike.

"I feel cooler than the motorbike drivers, because my engine is right here," he said, pointing to his wiry body.

Si Lingxiang, 21, wobbled up to the rest-stop on a light-framed blue bike he is riding on his 400 kilometre journey from the southern metropolis of Guangzhou to Pingnan in Guangxi.

"It's my fourth day of cycling, the seat is too small and my bottom aches," said Si, who slept the previous night in an abandoned school guardpost.

The rest stop in the city of Wuzhou has proved a publicity coup for the local Communist party committee, whose red banners jostled with posters promoting energy drinks to help with staying awake.

"Party cadres wish brothers and sisters returning home a safe journey," one read.

Nearby, on a public notice board where travellers inscribed their names with a black marker pen, one had written a short poem.

"My vehicle is cheap, I'm old and I have a lot of luggage, braving these windy roads needs courage," it read, signed "Worker returning home".

"If I'd known before I travelled this far, I'd long ago have bought an expensive car."