The construction of the Beijing-Shanghai high-speed rail link, China's longest express rail route, has entered into its crucial final stage, with its bottleneck section in Shanghai's Jiading county's Anting town successfully linked-up late last month.

Some 1,000 workers from the China Communications Construction Company (CCCC) Fourth Harbor Engineering Co Ltd, one of the leading builders of the railway construction project, worked 24 hours a day, seven days a week on a rotational basis to ensure the process met its deadline. The overall project is due for completion in 2011, in time to begin operations in 2012.

High-speed rail travel, largely the preserve of countries such as Japan and France until the 1990s, is now sweeping across China. China's hi-speed network will be nearly as large as that of the rest of the world's put together when the 1,300 km Beijing to Shanghai line is completed.

With an investment of 220.9 billion yuan ($31.6 billion), the route, linking China's two most populous regions, is the single most expensive construction project in China since 1949.

Commenting on the challenges facing the company, Zhao Zhongchen, project manager of CCCC's Fourth Harbor Engineering Co, said: "The schedule is so tight, and there are so many technical difficulties we have to overcome. Workers are divided into 3 groups to work 24 hours to maintain the required pace of the construction process."

The recently linked up section spans a 108 m long arched bridge and runs above a highway in Shanghai's Hongqiao district. Cars speed through the arch on which workers are hazardously welding. Along the bridge, a long eye-catching poster, styled like a military slogan, urges ever harder and faster work.

The tracks in the Yangtze-River Delta have to go through difficult terrain, interspersed with rivers and canal networks, according to Hu Wei, the technical director of project construction.

To simplify the logistic of providing raw materials, a supporting column production facility has been built in Shanghai's Jiading county, close to the rail construction site.

"Because we require very high technical standards for the materials' structure and design, we have to maintain tight control over the production process. The contractor and the Ministry of Railway conduct frequent inspection of our plant," said Liang Shaojie, the head of the supporting column factory, one of six such installations opened as part of CCCC's Beijing Shanghai Express rail construction project.

Liang said: "All the delicate positionings are made by machines instead of by hand in order to avoid even slight measuring errors."

To insure compliance with safety issues, the company organizes a series of safety training classes for construction workers every month.

Hu said: "The Beijing-Shanghai high-speed railway is a high-profile project that has attracted attention from across the world and any serious accidents would damage its reputation."

Construction work on the Beijing-Shanghai high-speed railway, which will have a running speed of 350 km per hour once completed, began in April 2008.

The 1,318-km-long railway line will cut the journey time between China's capital and its eastern financial hub in half, reducing it to just five hours. It will also have a one-way transport capacity of 80 million passengers and more than 100 million tonnes of cargo annually, according to the Ministry of Railways (MOR).

The line will cross Beijing, Tianjin, Hebei, Shandong, Anhui, Jiangsu before reaching Shanghai. It connects two major economic zones - Bohai Bay and the Yangtze River Delta.

One fourth of the country's population live in these two economically prosperous regions, with the local GDP accounting for 40 percent of the national total.

The Beijing-Shanghai High-Speed Railway Co Ltd was set up in December 2007 to take charge of the construction and has a registered capital of 115 billion yuan.