INTRO: Construction of a railway to Lhasa was started in 1958, but halted in the early 1980s until technical challenges could be overcome. Two decades later, Chinese Railways is poised to start work on an 1100 km railway through some of the world’s toughest terrain

BYLINE: Wang Teh Lei and Xu Shi Fu*

LATER THIS YEAR work will get under way on the construction of a rail link to the Tibetan city of Lhasa. The long-proposed project was finally approved by China’s State Council in February, and was immediately incorporated as a key project in the 10th Five Year Plan (2001-2005). Construction is expected to take around five years to complete, at an estimated cost of 13·9bn yuan.

The new line is, in fact, the second stage of the Qinghai - Tibet railway project which was launched in 1958. The Chinese government decided to build a railway into Tibet, and the initial 845 km from Xining, the capital of Qinghai province, to Golmud was completed and opened to traffic in 1984. But because of financial and technical problems the project was halted at that point.

Now it has been decided that the time is right to continue the work. The 1118 km preferred route from Golmud to Lhasa, now officially designated as the capital of the Xizhang Autonomous Region, will run via Wuli, Yanshiping, and Wenquan in Qinghai province and then via Andom, Naqu, Dangxiong, and Yangbajing in Tibet. Its completion will end Tibet’s long-standing history of not having an inch of railway.

The railway is expected to have a significant impact on the local economy, both during construction and following completion. It will boost considerably the domestic market and provide many jobs for the local labour force, promising a prosperous future for both Xizhang and Qinghai.

Difficult terrain

The Tibet Plateau poses a major challenge to railway builders, as it lies at an elevation of 4000m above sea level. The mountain ranges at Kunlun and Tanggula restrict access to the plateau, helping to isolate the region. At present around 90% of all outbound freight and 85% of inbound traffic moves by lorry over the north-south Qinghai - Xizhang highway to and from the railhead at Golmud. Together with the transhipment times, this results in a long journey time of typically two or three days. A small proportion of freight traffic moves via the Sichuan - Xizhang road to the east. There is also a limited air service for passengers to and from Chengdu.

Over the past couple of years, the Ministry of Railways has prepared four alternative projects for a rail link to Tibet, ready for a final selection by the state government. These would run to Lhasa from Xining (Qinghai), Chengdu (Sichuan), Kunming (Yunnan) or Lanzhou (Gansu). To ensure a fair comparison, all four routes were designed to handle 8 million tonnes a year. In the initial years following completion, the line is expected to carry around 565000 passengers and 1 million tonnes of freight a year.

After the comparative analysis (Table I), the Qinghai - Xizhang line was again selected as the best option, thanks to its shorter length, shorter construction time, lower cost and comparative ease of construction. Furthermore, this route offers shorter links overall from Xizhang to the provinces of central and eastern China.

Table II lists the various technical challenges which will have to be overcome to construct this line across the plateau. A major factor in favour of the Qinghai route was that the biggest problems on this route were the need to harness and control the frozen earth, and to prevent mudstone flow. Chinese Railways has already developed techniques to cope with these two problems, whereas some of the unsolved challenges posed a bigger threat on the other routes.

From the present railhead at Nanshankou, just south of Golmud, the line will climb steeply through the Kunlun pass to reach the plateau. Passing across areas of frozen desert, the line will follow the existing road through the upper watershed of the Jinshajiang river system in southwest Qinghai, before climbing again to cross the Tanggula pass to reach Tibet itself. Beyond Naqu the route runs over the Karchen and Gureng passes which lie above 5000m. From Yangbajing there would be a steep descent into the Bramaputra watershed to reach Lhasa.

Operational considerations

The Ministry of Railways has been looking at the technical implications of train operation in a high plateau environment, and has drawn up a number of design and operational principles to simplify the task.

These include the use of as large radius curves as possible in the terrain. With no external electric power supply available, the line will be operated by diesel locomotives, operating with up to three units in multiple where necessary. Train weights will be kept low to allow faster speeds on the steep gradients. The target journey times for passenger services include a maximum of 50h for Lhasa to Beijing, 20h for Lhasa - Lanzhou and 10h for Lhasa - Golmud.

To protect the fragile environment, solar heating or oil will be used in the stations instead of traditional wood-burning stoves. Garbage disposal will also be restricted to a few designated locations, to avoid pollution, and special measures are planned to protect the Kekexili, Shajiangyuan and Qiangtang ecological areas.

Final engineering design is now under way, and the Ministry expects to issue tenders shortly for preliminary works and the supply of materials. Studies are also under way into the possible physical changes affecting people working on the plateau, and special staff training programmes are envisaged.

TABLE: Table I. Comparison of four projected routes to Tibet

Project Qinghai Sichuan Yunnan Gansu

Length km 1118 1927 1594 2126

Length of bridges and tunnels km 30·6 819·24 710·65 438·69

Longest tunnel m 1210 19500 15300 8800

Bridges and tunnels as % of total line 2·8 42·5 42·97 20·6

Cost m yuan/km 12890 39850 39520 30030

Lhasa - Beijing km 3952 4063 5204 4022

Lhasa - Shanghai km 4326 4366 5089 4396

TABLE: Table II. Principal technical problems to be considered

Frozen earth Solved

Mudstone flow Solved

Crumbling ground Unsolved

Rock slip and scattering Unsolved

Rock burst Unsolved

Terrestrial heat Unsolved

Seismic activity Unsolved

Avalanches Unsolved

CAPTION: The new line will run alongside the existing road across frozen

deserts through the southern part of Qinghai

CAPTION: The threat of landslip requires carefully designed engineering solutions, as on the existing lines from Henyang to Guangzhou (far left) and Chengdu to Kunming (left)

* Wang Teh Lei was formerly Professor at the Nanjing Railway Technical University. Xu Shi Fu was Chief Engineer at the Ministry of Railways’ Electric Computation Centre