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1. E-Learning Material for Civil Engineering Students IV Year Railways, Airways & Waterways (RCE-076) Unit 1 Topic : Rail Gauges (Affiliated to Dr. A.P.J Abdul Kalam Technical University, Lucknow, Uttar Pradesh) Shaping Young Minds with Skill Oriented & Value Based Education Department of Civil Engineering KIET Group of Institutions Delhi-NCR, Meerut Road (NH-58) Ghaziabad – 201206 www.kiet.edu

2. 2 Rail Gauges Rail gauge is the distance between the inner sides of the two parallel rails that make up a single railway line Rail gauge is the distance between two rails of a railroad. Sixty percent of the world's railways use a 4 feet 8½ inch (1435 mm) gauge, which is known as standard gauge or international gauge. Rail gauges larger than standard gauge are called broad gauge, and rail gauges smaller than standard are called narrow gauge. A dual gauge railway has three or four rails positioned so that trains of two different gauges can use it. A place where different gauges meet is called a break of gauge.

3. Factors affecting the choice of a gauge Following are the factors affecting the choice of a gauge: Traffic Condition: If the intensity of traffic on the track is likely to be more, a gauge wider than the standard gauge is suitable. Development of Poor Areas: The narrow gauges are laid in certain parts of the world to develop a poor area and thus link the poor area with the outside developed world. Cost of Track: The cost of railway track is directly proportional to the width of its gauge. If the fund available is not sufficient to construct a standard gauge, a metre gauge or a narrow gauge is preferred rather than to have no railways at all. 6

4. Speed of Movement: The speed of a train is a function of the diameter of wheel which in turn is limited by the gauge. The wheel diameter is usually about 0.75 times the gauge width and thus, the speed of a train is almost proportional to the gauge. If higher speeds are to be attained, the B.G track is preferred to the M.G or N.G track. Nature of Country: In mountainous country, it is advisable to have a narrow gauge of the track since it is more flexible and can be laid to a smaller radius on the curves. This is the main reason why some important railways, covering thousands of kilometers, are laid with a gauge as narrow as 610 mm. 7

5. 8 When the clear horizontal distance between the inner faces of two parallel rails forming a track is 1676mm the gauge is called Broad Gauge (B.G) This gauge is also known as standard gauge of India and is the broadest gauge of the world. The Other countries using the Broad Gauge are Pakistan, Bangladesh, Sri Lanka , Brazil, Argentine,etc.50% India’s railway tracks have been laid to this gauge. Broad Gauge

6. 9 Sui t ability Broad gauge is suitable under the following Conditions When sufficient funds are available for the railway project. When the prospects of revenue are very bright. This gauge is used for tracks in plain areas which are densely populated. For routes of maximum traffic, intensities and at places which are centers of industry and commerce. Suitable for high speed

7. When the clear horizontal distance between the inner faces of two parallel rails forming a track is 1000mm, the gauge is known as Metre Gauge (M.G) The other countries using Metre gauge are France, Switzerland, Argentine, etc. 40% of India’s railway tracks have been laid to this gauge. Suitability When the funds available for the railway project are inadequate. When traffic efficiency is moderate. When the prospects of revenue are not very bright. This gauge is used for tracks in under-developed areas and in terior a r eas Meter Gauge 13

8. 11 When the clear horizontal distance between the inner faces of two parallel rails forming a track is either 762mm or 610mm, the gauge is known as Narrow gauge (N.G) The other countries using narrow gauge are Britain, South Africa, etc. 10% of India’s railway tracks have been laid to this gauge . Suitability For low speed movement When the construction of a track with wider gauge is prohibited due to the provision of sharp curves, steep gradients, narrow bridges and tunnels etc. When the prospects of revenue are not very bright. This gauge is used in hilly and very thinly populated areas . Narrow Gauge