Kalka Shimla Railway

The Kalka–Shimla railway is a 2 ft 6 in (762 mm) narrow-gauge railway in North India which traverses a mostly-mountainous route from Kalka to Shimla. It is known for dramatic views of the hills and surrounding villages. The railway was built in 1898 to connect Shimla, the summer capital of India during the British Raj, with the rest of the Indian rail system. During its construction, 107 tunnels and 864 bridges were built along the route. The project's chief engineer was H. S. Harington.

Its early locomotives were manufactured by Sharp, Stewart and Company. Larger locomotives were introduced, which were manufactured by the Hunslet Engine Company. Diesel and diesel-hydraulic locomotives began operation in 1955 and 1970, respectively.

The Kalka Shimla Railway, a 96.6 kilometer long, single track working rail link built in the mid-19th century to provide a service to the highland town of Shimla is emblematic of the technical and material efforts to disenclave mountain populations through the railway. The world's highest multi-arc gallery bridge and the world's longest tunnel (at the time of construction) of the KSR were the a testimony toof the brilliantce engineering skills applied to make this a dream a reality.

The railway has 864 bridges and a ruling gradient of 1 in 33, or three percent. It has 919 curves, and the sharpest is 48 degrees (a radius of 122.93 feet or 37.47 m). Climbing from 656 meters (2,152 ft), the line ends at an elevation of 2,076 meters (6,811 ft) in Shimla—a difference in height of 1,420 meters (4,660 ft). It originally used 42 lb/yd (20.8 kg/m) rail, which was later replaced with 60 lb/yd (29.8 kg/m) rail. One hundred seven tunnels were originally built, and 102 remain in use.

History & Other Facts
The Kalka Shimla Railway was built during the British rule in India with an aim to connect by Shimla the summer capital of British Indian rail network. The rail network holds the Guinness Book of World Records for its 96 kilometers steepest rise in the altitude with crossover of 800 bridges and viaducts, it is one of the most beautiful hill railways in India. It was considered the “crown jewel” of the Indian National Railways during British times.

Kalka Shimla Railway (KSR), a 96.6 kilometer long a single track working rail link was built in the mid-19th century to provide a service to the highland town of Shimla, it is emblematic of the technical and material efforts to disincline mountain populations through the railway. The world's highest multi-arch gallery bridge at Kanoh and the world's longest tunnel at Barog(at the time of construction) of the KSR were the testimony of the brilliant engineering skills applied to make this a dream a reality. Then the Shimla region took on considerable political importance as the Indian Colonial government decided to take up summer residence there, because of the healthier climate linked to the altitude. The question of transport to the Himalayan foothills, the Delhi region and the Ganges plain then became crucial. The possibility of rail link was mentioned as early as 1847.