CHINA's rapid economic growth of the past 20 years may have slowed in the first half of 2013, but the country's appetite for natural resources continues unabated.
Australia, Brazil and other countries in Southeast Asia have ridden the crest of China's resource boom to reap huge profits in the past few years; China imported 743 million tonnes of iron-ore and 289 million tonnes of coal alone in 2012. But the country also possesses its own vast natural resource deposits which are crucial to its continuing economic development.
China is currently the world's foremost coal producer, doubling its output in the past 10 years to reach 3.5 billion tonnes in 2011 for a 49% share of overall worldwide production. Coal is now the source of 70% of the country's energy production. And while the Chinese government is encouraging the development of renewable energy, efforts are similarly intensifying to further increase coal extraction to meet demand from swelling urban populations as living standards rise, particularly in the growing Pearl River Delta region.
The Shuo Huang Railway (SHR) is one of five railways in a 1765km network owned by the Shenhua Group, China's leading coal miner which also controls and operates 13 coal-powered plants. The 588km SHR began operating in 2000 and carried 234 million tonnes of coal in 2012 from Shenchi South in the coal-rich Shanxi Province, close to the Shenfu-Dongsheng coal field, to Huanghua port on China's east coast, south of Beijing. Here the line connects with the 67.8km Huangwan Railway which runs from the port to Wanjia Terminal in Tianjin.
However, as Mr Xue Jilian, vice-president and top senior engineer of Shenhua Group, told IRJ at the International Heavy Haul Conference in Delhi earlier this year, China and Shenhua are hoping to get more from its railway infrastructure.
"As part of China's 12th five-year plan we were required to increase coal output to 600 million tonnes per year, which is a huge amount," Xue says. "We therefore have to make sure that coal production and transport can match each other. This is not only a demand from the Chinese economy, but a demand from ourselves, the Shenhua Group."
Xue says the aim is to increase capacity of the line by 30-40 million tonnes per year to reach 400-600 million tonnes in the next five to eight years. Work on this project began in 2009 by introducing longer trains and using more C80 25-tonne axleload wagons.
In 2010 this was stepped up with a review of the wireless system used for transferring high-bandwidth data for real-time onboard video surveillance, and low-latency data for multi-locomotive synchronisation signalling. This led to the pilot installation of the world's first railway 4G LTE network.
SHR decided to proceed with the LTE system due to the reduced complexity of installing and operating the system compared with GSM-R and other communications technologies. It was also attracted to its capability to deliver broadband-quality data services on a single platform with LTE considered less prone to radio interference.
Huawei has supplied the system which initially covers a 40km section of line. Features include a multi-locomotive synchronous control and command transmission system, functional number check, dispatching communication and on-board video surveillance services.
The synchronous locomotive system is enabling SHR to operate longer trains with multiple locomotives distributed along the train, which can be controlled by the lead locomotive, and is similar to technology already used in China on the Daqin heavy-haul line. Xue says the system is increasing the length of trains used and thus increasing capacity, while the video surveillance system is using LTE as a transmission network for maintenance purposes.
Successful tests of the LTE network are likely to result in an extended rollout in the future, and Xue says the project is being closely monitored by the Chinese government.
"The central government is paying a lot of attention to our project," he says. "We have the full support of the science department which is allowing us to use a service frequency channel for the test and it plans to allocate a special channel for future train operations."
While this project has helped SHR increase the frequency of services, the network remains a long way off achieving its overall capacity goal.
The railway is now operating almost at capacity, with 115 train pairs per day, including 36 pairs of 10,000-tonne trains. As a result a huge infrastructure improvement project is now underway with the aim of increasing axleloads to reach the target.
SHR currently operates wagons with axleloads of 21, 23.2 and 25 tonnes, with the maximum traction mass of 11,600 tonnes using 116 C80 wagons. Xue says the aim is to increase the axleload to 30 tonnes and make greater use of high-capacity C80 wagons supplied by CNR Qiqihar Railway Rolling Stock Company as well as new C100 wagons, which have an axleload of 30 tonnes. The railway will also procure an additional 81 9.6MW locomotives to add to its existing fleet of 17 high-powered units supplied by CSR Zhuzhou Electric Locomotive Company.
Xue says that it is inevitable that increasing axleloads and using longer, heavier trains will place greater stress on the infrastructure. As a result a study commenced in 2011 to identify how SHR might overcome these technical difficulties, with Xue and a team of technical experts from SHR presenting the results during the IHHA conference.
"We expected to find that increasing this axleload would result in a few problems on bridges, trackbed in tunnels and on conventional track in terms of the strength, fatigue and stiffness of the steel rails used on the line," Xue says. "We have already done a lot of strategic research with the status quo condition of the railway to identify solutions to upgrade the infrastructure. Our aim is to find out what the optimal solution is."
The railway has more than 64km of bridges, 77 tunnels with a total length of 66.4km, and over 450km of track which runs at grade. The paper states that in general the track and components are in good condition when operating at a 25-tonne axleload. However, a detailed analysis identified several existing problems which would be intensified if 30-tonne axleload traffic was allowed to run on the current infrastructure.
• Rail: while 75kg rails used on the line are consistent with international heavy-haul standards, reports of excessive rail wear on curves with radius of 500-800m and average rail length life of 40% of the North American equivalent, means that rail life will be severely hampered if axleloads are increased to 30 tonnes.
• Sleepers and fasteners: existing sleepers and fasteners are compatible with standards for 30-tonne axleloads. However, in some areas serious defects have been found including cracks at the centre sleeper and railseat, broken fasteners, above average loss of toe pressure, and rubber pad failures. Unofficial data has also identified sleeper lateral displacement of up to 5.1mm and gauge widening of up to 7.7mm in sharp curves.
• Ballast: on bridges, culverts and tunnels where ballast depth is less than 200mm compared with up to 800mm on approaches, longitudinal stiffness is no longer uniform so increasing axleloads will reduce track lateral stability, worsen track geometry and result in an increase in sleeper failures.
• Turnouts: increasing axleloads to over 30 tonnes will result in an increase in turnout failures, which currently have a service life of 80-250 million gross-tonnes.
• Bridges and culverts: at 30-tonne axleloads the operational loads will exceed the design load for all span range bridges and culverts, and exceed the load for small bridges and some medium and longer span bridges by 20% depending on the length of the train.
• Tunnels: minor leakage problems have been reported but these have been repaired and overall these structures are generally in good condition. However, increasing axleloads could result in problems with the tunnel bed and with inverted arches, problems with the supporting rock capacity due to additional stress.
• Subgrade: the line suffers from several sections of poor geological conditions and has shown gradual deterioration as traffic has increased. A remedy programme has though been successful and this would have to be repeated if axleloads are increased.
These findings subsequently led to a comprehensive testing programme carried out with the support of Transportation Technology Centre Inc (TTCI), United States.
A 43.4km test section with a maximum gradient of 1.2% was used which included 19 curves with a radius of between 500 and 1000m, most types of bridges and culverts, three tunnels, and different types of subgrade. Two steel truss bridges and one continuous pre-stressed concrete bridge were also tested beyond this section using a 25-tonne axleload train, while static tests and the use of two strengthening techniques were carried out on a 32m-span T-beam bridge.
The train used for line tests consisted of 10 C80 25-tonne axleload wagons, 10 C100 30-tonne axleload wagons, six K100 30-tonne axleload coal hopper wagons, 10 C70 23-tonne axleload wagons, and 10 C64 21-tonne axleload wagons. Tests were carried out at 60, 70 and 75km/h and led to a number of recommendations for the strengthening work required to accommodate 30-tonne axleload traffic.
SHR says that the basic track structure can accommodate 30-tonne axleloads, but this is not sustainable. Track strengthening work will consequently focus on improving track lateral resistance, sleeper bending moment, the anti-overturn capacity of fasteners installed on sharp curves, and to optimise turnout structure and materials by extending frog and point lives.
SHR subsequently designed and is testing two types of concrete sleepers and fastenings at TTCI's Heavy Access Load (HAL) test track in Pueblo, Colorado. Trials of the sleepers found positive moment of 22.57kN/m, an 18% improvement on the existing type III sleeper used, a 23% improvement in centre negative moment to 21.33kN/m, while lateral resistance between single sleeper and ballast came to 15.52kN, which is a 7% improvement.
Similar improvements were found with the new fasteners, which have a 12mm elastic range and a toe pressure of 12.5kN, a significant gain on current type II fasteners. This material was also applied for new rubber pads while SHR has designed three new 75-12 turnouts by optimising the shape of the switch rail and guide curve linearity as well as improving frog materials and cast technological parameters. Testing of these turnouts is underway on SHR's test section.
Bridge strengthening and tunnel reinforcement work is also taking place. Specifically reinforced concrete bridges and culverts with a span of less than 16m are using an endothecia steel-reinforced concrete structure, slab reinforcement or replacement, or the installation of a bonded steel plate to enhance the slab cross section.
For mid-range bridges of 16-32m, pre-stressed steel tendons and pre-stressed carbon fibre are being applied to increase strength. Similar reinforcement work is taking place on viaducts, of which SHR uses both single and double piers. For single lines, enlarging the pier section and installing drilled pile foundations is improving pier vertical and lateral loading capacity, while damper devices fixed between girders are altering the distribution of longitudinal forces between piers as a heavy-haul train passes. On double-track lines where capacity was found to be inadequate, a new two-line pier construction at the foundation, on the pier body and pier stud is being tested.
Finally reinforcement and improvement of tunnel structures is taking place. Ballast depth will be increased to 300-350mm when the existing depth is 250mm or less. If this is not possible elastic reinforced sleepers will be used to reduce the stresses inflicted by a passing train. In addition a combination of pile grouting and full-closed grouting, and consolidation grouting methods will reinforce the tunnel structure, while excavating the tunnel's well is intended to improve drainage.
SHR has invested Yuan 100m ($US 16.31m) in the research and development programme which the Chinese government has supported with a Yuan 30m grant. Xue says it is too early to estimate an overall cost of the entire construction programme, but the plan is to have a "project plan and blueprint for the upgrades in place by the end of 2013 and to begin real construction in 2014."
SHR's partnership with TTCI is indicative of the international support for the project and there was a great deal of interest at the IHHA. Xue says that Chinese railways can and are learning a lot from others from around the world which have gone through a similar capacity enhancement process. However, he hopes that SHR will eventually be a showcase for Chinese expertise in the heavy-haul arena as it continues to develop its infrastructure.
"We can only borrow their [North American] way of thinking as we look to develop our own technologies to suit Chinese conditions which are very different," he says. "If the upgrading project is a success it will help China to promote its railway technologies."