How India’s steepest railway conquered the mountains using a century-old rack and pinion system

Countries & Cities · Published 15 October 2026 Swipe more like this →

In short: The Nilgiri Mountain Railway is a marvel of engineering that climbs the steepest tracks in Asia. Built by the British, this UNESCO World Heritage site relies on a specialized rack system to navigate extreme gradients. Today, it remains a living piece of history, blending modern diesel power with vintage steam.

Conceived in 1854, the Nilgiri Mountain Railway faced decades of bureaucratic delays before finally opening for traffic in June 1899. Connecting Mettupalayam to Udhagamandalam, the line serves as India's only rack railway. To overcome the daunting terrain, engineers implemented the Abt rack and pinion system between Kallar and Coonoor, allowing trains to tackle an average gradient of 4.08 percent, with some sections reaching a staggering 8.33 percent incline.

The railway's distinct character is largely defined by its X Class steam locomotives. While many of these engines are over eighty years old, the fleet is maintained with remarkable dedication. In August 2021, the Golden Rock Railway Workshops completed the construction of a brand-new X Class locomotive, ensuring the tradition continues. These steam engines are essential for the rack-assisted climb, though diesel locomotives are now utilized for the section between Coonoor and Udhagamandalam to improve service reliability.

Designated as part of the Mountain Railways of India World Heritage site in 2005, the line is a repository of colonial-era technology. Stations like Udhagamandalam still house equipment from the early 1900s, including a 1907 weighing scale. To preserve its heritage status, the railway continues to issue traditional Edmondson-style manual tickets for the main journey, even while offering modern digital booking options for passengers. Spanning 45.8 kilometres, the route features 209 curves, 16 tunnels, and 250 bridges, offering a journey that remains one of the most unique rail experiences in the world.

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