The ever-increasing demand for network expansion and decongestion has put pressure on Indian Railways (IR) to enhance its line carrying capacity in terms of new lines, doubling of rail lines, and increasing axle loads and average speeds. IR is consistently taking initiatives to enhance its traffic carrying capacity with improved levels of safety, maintainability and reliability.
While the tracks currently used by IR do not support high speeds, they are, however, safe for both passenger and freight movement. The railway sector has a very low share of 35 per cent in the total freight traffic owing to low speeds of trains that move at an average of 25 kmph. In this backdrop, IR has launched Mission Raftaar, an ambitious programme with is a multipronged strategy for running high speed trains or bullet trains (with a speed of over 300 kmph) and semi-high speed trains (between 160 and 200 kmph), increasing the speed of existing trains and introducing train sets similar to Train 18.
In Union Budget 2019-20, the government has allocated Rs 658.37 billion to the railways. Of this, Rs 72.55 billion has been allocated for the construction of new lines, Rs 22 billion for gauge conversion, Rs 7 billion for line doubling, Rs 61.15 billion for rolling stock and Rs 17.5 billion for signalling and telecommunications. The budget envisages an investment of Rs 5 trillion on railway infrastructure between 2018 and 2030 in order to achieve the target of running all passenger trains at a speed of 160 kmph and freight trains of 25 tonne axle load at 100 kmph.
To achieve these targets, technological interventions are required to make/upgrade the design of ballasts, sleepers, fastenings, rails, bridges, etc. so that they are suitable for the anticipated loads and speed levels. There is also a need to introduce changes in the design of rail-wheel interaction and related components such as rolling stock suspension, wheel profile, etc. However, to select the most appropriate track component, it is imperative to learn about the actual forces likely to be encountered by them. Most of the railway systems throughout the world use a combination of standard track structure and standard design of rolling stock but their operating and maintenance conditions differ from each other. Therefore, the accurate assessment of dynamic augment, lateral and vertical forces and accelerations, offloading, etc. becomes critical to evaluate safety, stability and reliability of train operations. The provisions of the international test protocol for rail vehicles – UIC-518 – serve as comprehensive guidelines in this respect.
The most important element of a track structure is the correct capacity selection and its safety, reliability and maintainability in the long term. Rail capacity depends on the rail section, metallurgy and maintenance practices. The UIC 60 kg (60E1) rail model is the most widely accepted and used. For freight traffic, it has been found suitable for up to 250 kilonewton axle loads whereas for passenger corridors, it has been successfully used for operational speeds of up to 350 kmph. Other types of rail sections (high carbon rolled steel sections) that have been used but are not very prevalent are 68 kg (136 RE 14), used on US railroads on heavy haul, and 71 kg (141 lb). Among the rail metallurgy or grade, the most prevalent grades are R260, which is a slight variant of IR’s GR 880, and R350HT. Maintenance practices such as rail handling, ultrasonic flaw detection (USFD) protocol, rail grinding discipline, and design and maintenance standards of rolling stock also play a vital role in deciding rail metallurgy. After extensive research, IR has decided on grade R-350HT to achieve its target of increased speeds and higher loads. It is the most widely manufactured grade after R-260. This move has further opened up market opportunities for various steelmakers because of the high demand from the railways.
Another key component for track structures is the sleeper (tie) and fastening. Wider and heavier sleepers have been designed with the objective of handling 25 tonne axle loads. The new sleeper design has various advantages over the older one. It has enhanced frame resistance with higher track buckling resistance. It also helps reduce the destressing temperature resulting in reduced rail stress, particularly during winters. Moreover, its larger rail seat base prevents damage to elastic rail pads, a vital component for supporting both high speed and heavy axle load operations. The larger base of sleepers provides reduction of stress on the ballast and in turn on the formation. This is also the first time that IR has used improved fittings and design rail pads of increased thickness of 10 mm with impact attenuation property. The pad has a 30 per cent attenuation value that comes along with the sleeper and its area is 35 per cent higher.
Other important elements of the track structure include welding, USFD testing, track warrant systems, crew management systems (CMS), rail grinding, etc. The welding technology adopted by IR is at par with international standards, with complete transparency and monitoring on a real-time basis. It has also brought down the defect rate of zonal railways to less than 5 per cent. IR has further instructed Steel Authority of India Limited to roll out only long trails to reduce the joints in the tracks.
The monitoring of tracks is as important as their structure design and construction. Unlike advanced railway systems, IR does not have a predefined track possession window, and this makes maintenance and degradation unpredictable. IR has taken a number of steps on the technological front to carry out monitoring and maintenance of tracks. To mechanise the monitoring process, it has planned the introduction of vehicular USFD on all major routes in the next two to three years with one USFD already functional. It has also decided to introduce TWS and CMS on all major routes. One of the important measures being taken for site condition monitoring for rolling stock is the deployment of
wheel load impact detectors. A technology developed by the Institute for Maritime Technology, South Africa, for a broken rail detection system is also under trial. Meanwhile, IR is scouting around for more technologies for modernising its track infrastructure. The maintenance of tracks is expected to be completely mechanised by 2024 with the use of 2,879 machines, of which 948 machines are already functional.
Conclusion
Going forward, with IR targeting to commission about 1,772 km of new lines, 6,189 km of line doubling or tripling, 1,357 km of gauge conversion and electrification of 10,391 km of rail lines in 2019-20, network capacity will be significantly enhanced. With network expansion and decongestion plans on the anvil, there will be significant business opportunities for private contractors, consultants, equipment and technology suppliers, material suppliers and other ancillary market segments. IR has also been leveraging technology to reduce the reliance on human interface and efficient allocation of resources to improve safety. With high speed rails, manual inspections and patrolling of track will not be possible without controlling traffic. More advanced and new technologies will be needed to handle future traffic of high speeds and heavier axle loads for reliable and safe operations. Learning from past experience sufficed for low speed rails but the goals of high speed rails ask for investment in research and development. The crucial decision of technology selection will determine the performance of railways in the long run. The key to achieving the target is overcoming the resistance to change and adopting the most appropriate technology solutions along with increasing stakeholder participation. w
Based on a presentation by Vipul Kumar, Executive Director, Track (Modernisation), Railway Board, at a recent India Infrastructure Conference