Indian Railways is the life-line of nation providing transportation facility over the length and breadth of country. It’s vision is to provide efficient, affordable, customer-focused, environmentally sustainable integrated transportation solutions and to be the vehicle of inclusive growth, connecting regions, communities, ports and centers of industry, commerce, tourism and pilgrimage across the country.
Civil Engineering infrastructure is the largest static infrastructure of Indian Railways comprising of track, bridges, land, etc. Management of this huge infrastructure has to be done in accordance with the organization’s vision. Civil engineering department of Indian Railways manages and maintains all these infrastructures. Further, it has key role in the area of infrastructure development, technological leap in various fields, high speed travel and development of world class stations.
Earlier, wooden sleepers were used for laying the railway tracks but due to the depleting wooden resources and increasing concern of the ecological balance, the use of concrete sleepers was started and now it has completely replaced the wooden sleepers on entire Indian Railways. Concrete sleeper have several advantages over wooden sleepers as it does not rot like timber sleepers and its weight adds stability to the tracks, particularly with changes in temperature. It can also withstand fire hazards and has longer life than wooden sleepers. Besides, it requires less maintenance.
Automation in the sleeper industry aims at improving productivity, achieving zero defects and meeting just-in-time supply requirements of not only Indian Railways, but the Metro Rail systems and the Private Railway siding markets to cater to the exacting standards.
The “Long Line Technology” as the manufacturing process is called, is used to manufacture Pre-Stressed Concrete Sleepers in an automated environment. Some of the biggest advantages that this technology brings over the conventional technology are reduced dependency on manpower and substantial improvement in quality. Also, the casting time comes down by nearly 25% thereby increasing productivity. This technology helps in manufacturing large quantities of sleepers in least possible time. The regular operations of the sleeper plant such as de-moulding of sleepers, cutting of pre-stressed wire, HTS wire drawing are automated using machines. This technology permits relaxation and cutting of the prestressed strands and shakeout of the sleepers with no movement of the shuttering, thus eliminating all problems of maintenance or clearance adjustment connected with the moving parts. The long line system can be applied to any type of fastening: Pandrol, Vossloh, Stedef, D.E. Clips, Denik, KB, etc. The moulds are designed and created in such a way so as to allow changing of the necessary type of fastening simply by replacing the plates with the required cast and housing, the plates being screwed onto the structure of the mould.
The adherent wire system provides considerable savings in sleeper production based on the use of normal market products (pre-stress strands or rods) that do not need special processing or accessories – they are simply drawn between the pre-stressing heads, fixed with ordinary prestressing clamps and then pre-stressed.
Talking to RailNews, a Subhodh Kumar, AEN/P-Way from the Civil Engineering Department of Railways said, “Concrete Sleeper Plants prepares special kinds of sleepers which are required at different places across the length and breadth of the country and are capable of producing the high quality sleepers.”
Few companies have been recognised as the country’s largest Suppliers’ of concrete sleepers to the Indian Railways. Prominent ones among them are Patil Rail Infrastrructure Pvt Ltd, GPT Infraprojects Ltd, Econ Antri Limited, S.Subramanyan and Co., Usha Prestressed Sleeper Udyog Pvt Ltd., Vaman Prestressing Company Pvt ltd., These companies manufactures the pre-stressed concrete (PSC) sleepers across various Plants located in the country. Today these companies are some of the leading manufacturers and suppliers of all kinds of PSC Sleepers for Indian Railways and Railways subsidiaries like RVNL, RITES, IRCON and DFCCIL and also for all other reputed private sector companies like Tata Projects Limited, Larsen & Tubro Limited, Bajaj Group, Kalindee Rail Nirman (Engineers) Limited, etc who are engaged in Rail network and projects.
|Production Position of Concrete Sleeper Plants|
|Railway||Name of Plant||July-2018||Total
|1||CR||Bemco Sleepers Limited Khandwa||5937||2305||8242||29057|
|2||CR||Daya Engineering Work Poles Pvt. Ltd.||2979||3797||6776||26165|
|3||CR||Kaprecon Sleeper Works Pvt. Ltd.||3564||0||3564||14693|
|4||CR||Malu Sleepers Maharashtra Pvt. Ltd.||1795||2911||4706||21690|
|7||CR||Stresscrete Pvt. Ltd.||1734||1427||3161||10943|
|73||WR||Manibhai and Bros. sleeper Kharsalia||1836||5814||7650||55539|
|74||WR||Patil Rail Infrastrructure PVt LTd Udvada||4473||5025||9498||66903|
|75||WR||S.Subrahmanyan and Co Kharsalia||4816||6040||10856||71255|
|76||WR||Usha prestressed sleeper udyog Godhra||6247||6782||13029||69010|
|77||WR||Vaman Prestressing Co Pvt Ltd Digsar||5514||6279||11793||55057|
The structure and the design for concrete sleepers had been constantly undergoing changes in conjunction with the R&D of Indian Railways to suit the changing requirements, be it operational, environment or otherwise. With the adoption of M60 grade cement by the companies, the life of these sleepers increased. It is noteworthy to mention here that with the increased base width, the ballast pressure came down by 10% leading to proportionate savings on ballast and maintenance costs.
The Range of manufacturing are as follows:
- Broad Gauge 52 Kg/60Kg MBC Sleepers (RT-2495 & RT-2496).
- Level Crossing Sleepers (RT-4148 & RT-4148A).
- Slack Gauge Sleepers (RT-4170, RT-4171, RT-4172 & RT-4173).
- Broad Guage Special Sleepers – Wider Guage (RT-4183, RT-4184, RT-4185 & RT-4186).
- Bridge Approach Sleepers (RT-4088, RT-4089, RT-4097).
- Shallow Sleepers (RT-4852).
- Heavy Axle Load PSC Sleepers (RT-7008, RT-8224, RT-8225 RT-8228 and RT-8229 to RT-8237).
- 1 in 12 Point and Crossing Sleepers (RT-4218 & RT-4732).
- 1 in 8.5 Point Crossing Sleepers (RT-4865).
- Derailing Switch Sleepers (RT-6068).
- Rerailing Ramp Sleepers (RT-6420 to RT-6440).
- Diamond Crossing Sleepers (Without Slip, Single Slip & Double Slip) (RT-5362, RT-5363 & RT-5364).
- Rex Lock Sleepers (Special Fastening of Rex Lock provided by Escorts India Limited) (A4-97-EQ41-5).
Indian Railways has plans to go for higher axle loads in coming years and with the onset of Dedicated Freight Corridors and High Speed / Semi-High Speed Rail systems coming up, the new design for concrete sleepers will suit future challenging requirements of the Indian Railways. The companies also also using special strand wire with higher UTS by which the overall weight of steel per sleepers will be brought down by 25%.
In case of Patil Rail Infrastructure, the company has its manufacturing plants located at Anara, Bhubaneshwar (Kaipadar Road), Bilaspur (Kargi Road), Madurai (Tirumangalam), Tumkur, Udwada and Wadiyaram while the new automated plants are coming up at Badi Khatu and Bhurwal. The company is also the country’s first ISO certified concrete manufacturing plant.
The Concrete Sleepers manufactured by these companies are suitable for:
- Normal Broad Gauge: This sleeper has a trapezoidal cross section having a width of 154 mm at the top and 250 mm at the bottom and a height of 210 mm at rail seat.
- Points & Crossing: These specialized sleepers are used to hold switches, CMS crossings and lead rails for main line and turnouts. High speed trains can run on these PSC layouts with utmost safety.
- Guard Rail: These are used at the approaches to girder bridges to prevent a derailed train from capsizing.
- Switch Expansion Joints: These are PSC sleepers for switch expansion joints (with 120 mm maximum gap) for long welded rails for 52 kg & 60 kg rails using corresponding chairs.
- Check Rail on Curves: Check rails are absolutely essential to offer an inner side for sharper curves, which are more than 50 to prevent derailment.
- Level Crossings: This is formed at various points where a road crosses a railway track at the same level and sleepers used here are made with 60 kg UIC or 52 kg check rail.
- Dual Gauge: The unique pre-stressed concrete dual gauge sleepers have been designed to cater to handle meter and broad gauge trains so that both trains can run on the same track. All the sleepers are manufactured under stress bench system with very strict quality control measures.
The Concrete Sleeper plant produces various kinds of specialized sleepers. It produces level crossing sleepers (sleepers used at level crossings are special ones as roads are also built over it), SEJ sleepers (Switch Expansion Joints- sleeper used to connect joints of the railway tracks), Turn out sleepers (sleepers used at the turnings).
It also produces diamond cross-over and scissors cross-over. Concrete sleepers for turnouts are much longer than normal sleepers, have gaps for switch motors, have sleepers individually designed, and are generally made by a small number of specialist manufactures.
These specialised sleepers are manufactured through the stress bench method. Here, moulds of sleepers are kept on the bench and high quality steel tendons are put on it. The steel tendons are pulled between the two end abutments (also called bulkheads) prior to the casting of concrete. The abutments are fixed at the ends of a prestressing bed. After fixing and welding of fittings the concrete is poured in each of the mould. After that steam curing is done in which the prepared sleepers are subjected to steam. Finally, moulds are removed and water curing takes place.
Later, the stage of testing is done in which each of the sleepers is subjected to intense load to check whether it can sustain heavy load or not. The checking is also being done to check cracks in the sleeper.