on the railway are B-Class, built by Sharp, Stewart and Company and later the North British Locomotive Company between 1889 and 1925. A total of 34 were built, but by 2005 only 12 were still in use or being repaired by the railway. In 2002, No. 787 was rebuilt for oil firing on the same principle as that used on Nilgiri Mountain Railway No. 37395. A diesel-powered generator was fitted to operate the oil burner and an electrically-driven feed pump, and a diesel-powered compressor was fitted to power the braking system. The locomotive was also fitted with a feedwater heater. The rebuild dramatically changed its appearance. Trials of the refitted locomotive were disappointing, and it never entered regular service; in early 2011, it was in the Tindharia Works awaiting re-conversion to coal-firing. In early 2019 B787 was restored cosmetically and is now displayed on a plinth outside Siliguri Junction station. In March 2001, No. 794 was transferred to the Matheran Hill Railway for a "joy train" (a steam-hauled tourist train) on that railway. It entered service there in May 2002. Diesel Six diesel locomotives are in use: Nos. 600–605 of the NDM-6 class. Past The DHR purchased the third Garratt locomotive built, a D Class , in 1910. Only one DHR steam locomotive has been taken out of India: DHR 778 (originally No. 19). After many years out of use at the Hesston Steam Museum, it was sold to Adrian Shooter in the UK and restored to working order. Now on a private railway (the Beeches Light Railway in Oxfordshire), it has run on the Ffestiniog Railway, the Launceston Steam Railway and the Leighton Buzzard Light Railway. Route The line follows Hill Cart Road, which is part of National Highway 110. The track is on the roadside for long stretches, and both track and road might be blocked by a rockslide. Since a length of the road is flanked with buildings, the railway line often resembles urban tramway tracks. To warn pedestrians and drivers of an approaching train, engines are equipped with very loud horns and whistles which train drivers sound almost constantly. A major difficulty faced by the DHR was the steepness of the terrain. Loops and zig-zags were incorporated along the route to achieve a comfortable gradient. When the train moves forward, reverses and then moves forward again (climbing a slope while doing so), it gains altitude along