TRACK AND GAUGE

Indian railways uses four gauges, the 1,676 mm (5 ft 6 in) broad gauge which is wider than the 1,435 mm (4 ft 8 ¹⁄₂ in) standard gauge; the 1,000 mm (3 ft 3 ³⁄₈ in) metre gauge; and two narrow gauges, 762 mm (2 ft 6 in) and 610 mm (2 ft). Track sections are rated for speeds ranging from 75 to 160 km/h (47 to 99 mph).

The total length of track used by Indian Railways is about 115,000 km (71,000 mi) while the total route length of the network is 67,312 km (41,826 mi).About 27,999 km (17,398 mi) or 42% of the route-kilometre was electrified, as of 31 March 2016.

 
In some regions with less traffic, the metre gauge (1,000 mm (3 ft 3Broad gauge is the predominant gauge used by Indian Railways. Indian broad gauge—1,676 mm (5 ft 6 in)—is the most widely used gauge in India with 108,500 km (67,400 mi) of track length (94% of entire track length of all the gauges) and 59,400 km (36,900 mi) of route-kilometre (91% of entire route-kilometre of all the gauges).

³⁄₈ in)) is common, although the Unigauge project is in progress toconvert all tracks to broad gauge. The metre gauge has about 5,000 km (3,100 mi) of track length (4% of entire track length of all the gauges) and 4,100 km (2,500 mi) of route-kilometre (7% of entire route-kilometre of all the gauges).

The Narrow gauges are present on a few routes, lying in hilly terrains and in some erstwhile private railways (on cost considerations), which are usually difficult to convert to broad gauge. Narrow gauges have 1,500 route-kilometre. The Kalka-Shimla Railway, the Kangra Valley Railway and the Darjeeling Himalayan Railway are three notable hill lines that use narrow gauge, but the Nilgiri Mountain Railway is a metre gauge track. These four rail lines will not be converted under the Unigauge project.

Sleepers (ties) are made up of prestressed concrete, or steel or cast iron posts, though teak sleepers are still in use on a few older lines. The prestressed concrete sleeper is in wide use today. Metal sleepers were extensively used before the advent of concrete sleepers. Indian Railways divides the country into four zones on the basis of the range of track temperature. The greatest temperature variations occur in Rajasthan.The share of broad gauge in the total route-kilometre has been steadily rising, increasing from 47% (25,258 route-km) in 1951 to 86% in 2012 whereas the share of metre gauge has declined from 45% (24,185 route-km) to 10% in the same period and the share of narrow gauges has decreased from 8% to 3%. About 27,999 route-km of Indian railways is electrified.

Research and development

Indian Railways has a full-fledged organisation known as Research Designs and Standards Organisation (RDSO), located at Lucknow for all research, designs and standardisation tasks.

In August 2013, Indian Railways entered into a partnership with Indian Institute of Technology (Madras) to develop technology to tap solar energy for lighting and air-conditioning in the coaches. This would significantly reduce the fossil fuel dependency for Indian Railways.

Recently it developed and tested the Improved Automated Fire Alarm System in Rajdhani Express Trains. It is intended that the system be applied to AC coaches of all regular trains.