Indian Train

Since the first railways appeared in India in the 19th century, locomotives of various designs have been imported from the UK and the USA, and of course a large number were actually built in India, initially using imported technology and designs.
Fortunately examples of most major designs have been preserved in the Rail Transport Museum in Delhi. Locomotives from all three gauges (broad, metre and narrow) have been beautifully restored, many in their original railway company colours. Amongst those on show is the oldest surviving engine in India, built in 1855, and a diminutive two-foot-gauge locl from Darjeeling, making a stark contrast beside a 234-ton Beyer Garratt locomotive.
The remaining 3000 or so broad-gauge steam locomotives in India are of only two basic and rather austere designs. The more attractive of the two is the distinctive semi-streamlined WP class introduced in 1947. The engines of the WG class were originally built for heavy freight traffic, but as most of these as shunting local freight and slow passenger trains. There’s plenty of room on the footplate of these broad-gauge giants and many of the crew are not averse to having you abroad; it’s always worth asking.
The mainstays of the metre-gauge system are the post-war YP (passenger) and YG (freight) designs which are found everywhere. A large number were built in India, the last YG being made in 1972. A handful of the attractive YD and YB classes have managed to survive. The YDs still slog their way up the ghats east of Goa on local passenger trains, while the last few YBs are found on the Western Railway in Gujarat.
Other curiosities are the narrow-gauge lines: the rack railway to Ooty, which uses Swiss engines; the Darjeeling Himalayan Railway, arguably the most famous and most spectacular steam railway in the world; and the lines from Kalka to Shimla and from Neral (near Bombay) to Matheran. With the exception of the Darjeeling line, all these routes are now worked by diesels.
Although steam locomotives will be around in India will past the year 2000, the variety and colour that remain will certainly have disappeared before then. But before you point that camera, a word of warning. Indian authorities can go overboard when it comes to railway security, so try to ensure that no police or other officials are around.

Gauge

There are three gauge types in India; broad, metre and narrow, and what you want nearly as much as a mail or express train is broad gauge. In broad guage the rails are 1.676 metres apart; metre gauge is, as it says, one metre wide; narrow gauge is either 0.762 metres (two feet six inches) or 0.610 metres (two feet).
Broad gauge has a major advantage – it is much faster. The carriages are much the same between broad gauge and metre gauge, but on narrow gauge they are narrower and the accommodation less comfortable. In areas where there are no broad-gauge lines it may be worth taking a bus, which will often be faster. These areas include Rajasthan and the northern Bihar and Uttar Pradesh areas towards the Nepal border.