Millions have begun heading home from Beijing for Lunar New Year, but many this year will not return as China's capital becomes increasingly unwelcoming for the migrants from the provinces who once powered its economy.

Crowds carrying parcels and suitcases and packs of instant noodles gathered at the Beijing West Railway Station Saturday, waiting to board packed trains ahead of the most important holiday on the Chinese calendar.

Throughout the country, hundreds of millions will be on the move in the world's largest annual human migration. 

Among them Saturday was Li Wen, a 47-year-old restaurant worker and one of many Beijing residents who has bought a one-way ticket in the face of a campaign of demolitions that has made life impossible for many of the city's migrant workers.  

She moved to the capital ten years ago to earn money to support her daughter, who now attends university in Chengdu.

However, many migrants like her are no longer welcome in the overcrowded city, which seeks to cap its population at 23 million by 2020 and demolish 40 million square meters of illegal structures — mostly shops and homes for low-income residents.

"I came to Beijing to work because the salaries in the capital are much better than elsewhere. But in my neighborhood, many of the hutong (alleyway single-story) homes have been torn down already," Li told AFP.  

"I won't be able to survive in the city if I need to pay three times more to rent in a normal apartment building," she said. 

BREATHING SPACE

Travellers must be home by Thursday to usher in the new year on Friday. But getting there is an ordeal.

On one 28-hour train journey from Beijing to the southwestern city of Chengdu, only the lucky passengers were able to snag a seat.

Many had to stand for the entire trip, clogging the aisles. Meals on plastic trays were passed from passenger to passenger. 

To get some breathing space in the hot and stuffy carriages, some people stood on top of the seats, surveying the scene below. 

But few complained. They passed the time playing on smartphones, sharing food and chatting with fellow passengers. Even the children mostly stayed quiet.

Yet the mood in the dining car was somber despite the cheerful red and gold Lunar New Year decorations. Like Li, some of those stuffed into the train do not plan to return to Beijing when the 15-day festival is over.  

"The Beijing authorities don't want migrant workers to reside here. They call it economic upgrading," said Pablo Wang of China Labour Bulletin.

"A lot of migrants are going back home. With these policies, they cannot come back."

Authorities say the campaign to demolish sub-standard housing, which kicked into high gear after a fire in an illegal structure killed 19 people in November, is necessary to clean the city up once and for all. 

Fire safety is a major problem in the city's cheap migrant housing, which often has jerry-rigged electrical wiring and a lack of emergency exits.

But the brutal efficiency of the demolitions and mass evictions over the past year has provoked an unusual public outcry that has put officials on edge.

THREE BILLION TRIPS

Although relegated to the periphery, migrants have kept China's economy humming -- handling the dreary, difficult, dirty and sometimes dangerous work that the city's permanent residents shun.

Industries like construction, domestic work and sanitation are almost completely staffed by migrants. Their exodus from Beijing took a toll on the city's growth last year, which slowed from a year earlier.

On Sunday transport officials reported a slight drop in the number of trips made during the first ten days of this year's holiday travel period. Chinese passengers made 732 million trips by railway, road, waterway and plane from February 1 to February 10, down three percent from last year.

The transport ministry attributed the drop to university students and migrant workers who returned home before the rush started. Many migrants left the city last November and December as authorities evicted hundreds of thousands.

During last year's lunar rush, Chinese passengers made almost three billion trips during the festival travel period, according to the official Xinhua news agency.

Li has still not yet decided if she will try her luck in a different city after the holiday.

"My daughter just started university so she won't be able to work, and I'll have to keep working to support her," she said.

"But I don't have any plans.... I'll just see what happens."