The Darjeeling railway was conceived by Franklin Prestage, the Agent or General Manager of the Eastern Bengal State Railway. Tea estates had opened in the Darjeeling area in the 1870s, and the newly opened Calcutta-Siliguri line saw considerable traffic. Prestage proposed in 1878 to build a 2' NG railway line on the Hill Cart Road. The original line of the DHR was constructed between 1879 and 1885 and was originally named the Darjeeling Steam Tramway Co. The DHR was actually opened to traffic in 1881, when it became the Darjeeling Himalayan Railway Co. The ruling gradient is 1:16, and the sharpest curve is of radius 18m. There are five zig-zags (switchbacks) and four full loops, of which two are double spirals. Services are operated today with several ancient steam locos kept alive by the Tindharia Works. The working locos date from as far back as 1899 and 1904; the newest ones are from 1925. A couple of narrow-gauge diesel locos have been pressed into service on the DHR in recent years.
The crew for the trains in the old days generally consisted of a driver, a fireman, a coal breaker, a coal passer, and two sanders who stood at the front of the engine. Cargo hauled included rice and tea, other mixed freight, and passengers from Siliguri (500' altitude) to Ghum (7407'), and finally to Darjeeling (7000') over 51 miles (82km). The DHR locos typically racked up 1200 to 1300 miles in each month of service.
Originally, the DHR had two branches. The Kishanganj branch, running west-south-west of Siliguri, was 107km long and was converted to MG and connected to the NER system at Barsoi during the construction of the Assam Rail Link in 1948. The Kishanganj branch used 'A' class Pacifics, none of which survive today. The other branch was the Kalimpong Road (Gelkhola) branch, following the Teesta valley, 36km long, which was closed in 1950 following floods that swept away the trackbeds.
Currently, it operates three routes
Kurseong - Darjeeling - Kurseong (daily)
New Jalpaiguri - Darjeeling - New Jalpaiguri (daily)
New Jalpaiguri - Silliguri Jn. - New Jalpaiguri
Shorter excursions between Ghum and Darjeeling are run often, known as the 'Joy Train' services and intended for tourists. These are always steam-hauled, while the other services are sometimes steam-hauled and sometimes diesel-hauled these days.