Kalka–Shimla Railway

Based on Wikipedia: Kalka–Shimla Railway

A Railway That Climbs Into the Clouds

Imagine a train that rises more than a mile into the sky, threading through over a hundred tunnels, crossing nearly a thousand bridges, and bending around more than nine hundred curves—all while offering views so dramatic that UNESCO declared the entire route a World Heritage Site. This is the Kalka–Shimla Railway, a narrow-gauge engineering marvel carved into the foothills of the Himalayas.

The train climbs from Kalka, sitting at just 656 meters above sea level, to Shimla at 2,075 meters. That's an ascent of 1,419 meters—nearly 4,700 feet—over a distance of about 96 kilometers. To put that in perspective, you start in humid plains where temperatures can soar to 45 degrees Celsius, and you end in a hill station where winter brings snow.

Why Build a Railway to the Sky?

The British built this railway for a very practical reason: bureaucracy.

Shimla became the summer capital of British India in 1864. The British had settled there after the first Anglo-Gurkha War, drawn by its elevation of over 7,100 feet and its escape from the punishing heat of the plains. But "summer capital" meant something extraordinary—twice each year, the entire government had to relocate. Everything. The Viceroy. The army headquarters. The clerks, the files, the furniture.

Before the railway, this journey required horse-drawn and ox-drawn carts struggling up treacherous mountain paths. The idea of connecting Shimla by rail first appeared in a letter to the Delhi Gazette in November 1847, but it would take half a century of surveys, debates, and false starts before construction began.

The Great Gauge Debate

Railway engineers faced a fundamental question: how do you build tracks up a mountain?

There were two main approaches. A rack railway uses a toothed rail between the regular rails, with a cogwheel on the locomotive that grips this rack to pull the train up steep grades. Think of it like a zipper for mountains. The alternative is an adhesion railway—a conventional train that relies purely on the friction between wheels and rails, but must follow gentler gradients that snake back and forth across the mountainside.

Surveys in the 1890s proposed both options. The rack lines would be more direct. The adhesion lines would be longer—roughly 108 to 112 kilometers—but simpler to maintain. After much debate, the engineers chose adhesion, accepting the longer route for the sake of reliability.

Then came another debate: how wide should the tracks be?

Construction began in 1898 on two-foot-gauge tracks—just 610 millimeters between the rails. For context, standard gauge in most of the world is 1,435 millimeters, and India's broad gauge is even wider at 1,676 millimeters. The narrow gauge allowed tighter curves around the mountains.

But the Indian Army objected. This was, after all, the route to their headquarters. They wanted wider tracks for strategic purposes. The government agreed, and in 1901 the contract was revised to widen the gauge to two feet six inches—762 millimeters. All the track built so far had to be ripped up and relaid. Some sources claim this regauging actually happened in 1905, after the line opened, which would have been an even more remarkable undertaking.

Numbers That Stagger the Imagination

The Kalka–Shimla Railway, when completed in 1903, represented one of the most ambitious mountain railway projects ever attempted. The statistics read like poetry written in steel and stone.

One hundred and seven tunnels were originally bored through the mountains. Landslides have claimed five of them over the decades, leaving 102 in active use. The longest tunnel stretches 1,143 meters near Barog station—over a kilometer of darkness through solid rock.

Nine hundred and eighty-eight bridges and viaducts carry the tracks across valleys and gorges. The most complex is Bridge Number 226, which spans such a deep chasm that engineers had to build it in five separate stages, stacking stone arches atop one another like a layer cake made of masonry.

Nine hundred and seventeen curves twist the route through the terrain. The sharpest bends the rails at a 48-degree angle, with a radius of just 37 meters—tight enough that the train seems to chase its own tail.

The ruling gradient is 1 in 33, meaning the train climbs one meter for every 33 meters it travels forward. That's a three percent grade, which sounds modest until you realize the train must maintain this climb for hours while hauling passengers and cargo.

The Economics of Altitude

The railway was built by a private company, the Delhi-Ambala-Kalka Railway, under a contract signed on June 29, 1898. The British government provided land free of charge but offered no financial guarantee. This was to be a purely commercial venture.

The initial estimate was about 8.7 million rupees. By the time Lord Curzon, the Viceroy of India, dedicated the line on November 9, 1903, costs had doubled. The difficult terrain, the constant engineering challenges, the sheer quantity of bridges and tunnels—it all added up.

The company was allowed to charge higher fares than other railways to compensate for the construction and maintenance costs. But even premium pricing couldn't make the line profitable. By 1904, the company had spent over 16.5 million rupees with no prospect of returns. The government purchased the railway on January 1, 1906, for just over 17 million rupees.

It had been a commercial failure. But as a feat of engineering and as a vital artery connecting the summer capital to the rest of India, it was irreplaceable.

Locomotives: From Steam to Diesel

The first engines to haul trains up to Shimla were borrowed—two small 0-4-0ST locomotives from the Darjeeling Himalayan Railway, converted from two-foot to two-foot-six-inch gauge. The designation "0-4-0ST" describes the wheel arrangement: no leading wheels, four driving wheels, no trailing wheels, and a saddle tank for water mounted over the boiler. These compact engines were essentially the smallest practical steam locomotives.

They proved too small. In 1902, ten slightly larger 0-4-2T locomotives arrived from Sharp, Stewart and Company in Britain. Each weighed about 21.5 tons and could manage the grades, but the railway needed more power.

Between 1904 and 1910, thirty 2-6-2T locomotives entered service. The "2-6-2" means two leading wheels, six driving wheels, and two trailing wheels—a much more substantial machine at 35 tons. These workhorses, built by Hunslet Engine Company and North British Locomotive Company, handled most traffic during the steam era.

An interesting experiment came in 1928: two Kitson-Meyer articulated locomotives. These were massive double-ended machines, essentially two locomotives joined together, with a 2-6-2+2-6-2 wheel arrangement. At 68 tons, they were too heavy and too hungry. It often took an entire day to assemble enough freight to justify running one of these giants. Shippers, frustrated by the wait, began sending goods by road instead. The big locomotives were transferred to another line and eventually converted to a different gauge entirely.

Diesel arrived in 1955 with the ZDM-1 class, articulated locomotives with two engines. More followed in the 1960s. Regular steam operation ended in 1971, though heritage steam runs occasionally still occur.

Today, the railway operates ZDM-3 diesel-hydraulic locomotives, producing about 700 horsepower and capable of 50 kilometers per hour. Six new versions built in 2008 and 2009 feature dual cabs, allowing the driver to see the track clearly in either direction—essential on a line with so many tunnels and curves.

The Coaches: An Early Experiment in Lightweight Design

Weight matters enormously on a mountain railway. Every extra kilogram the locomotive must haul up the grade is a kilogram of fuel burned.

The railway opened with conventional coaches, but the locomotives could only manage four bogie coaches at a time. In 1908, engineers rebuilt the entire coach fleet with steel frames and bodies, measuring 33 feet by 7 feet. Then they made a decision that was remarkably ahead of its time: they built the roofs from aluminum.

This was an early example of using aluminum in railway construction specifically to reduce weight. The weight savings allowed locomotives to haul six of the larger coaches instead of four—a fifty percent increase in capacity without requiring more powerful engines.

Today's trains include the Shivalik Deluxe Express with meal service, the Himalayan Queen connecting to express services to Delhi, and the Rail Motor—a first-class railbus with a glass roof and forward-facing views. The Shivalik Queen offers luxury carriages with wall-to-wall carpeting, large windows, and private accommodations for up to eight people per carriage.

Many trains now feature vistadomes—observation cars with glass roofs that allow passengers to gaze up at the mountains and sky as they climb.

Fossils from an Ancient Sea

The railway passes through terrain that tells a story far older than the British Empire or even human civilization.

Near Koti station, workers discovered a 20-million-year-old fossil of a plant stem, possibly an early flowering plant from the Miocene epoch. This region—now high in the Himalayan foothills—was once a coastal area of the Tethys Ocean, a vast sea that separated the ancient supercontinents. The fossil was buried in a paleo-flood event, preserved for eons as the Indian subcontinent crashed into Asia and pushed these seabeds up into mountains.

The Birbal Sahni Institute of Palaeosciences is analyzing the fossil's microscopic structure to understand how India's vegetation evolved. There are plans to designate the discovery site as a Geo Heritage Site to attract scientific tourism.

Other fossil sites dot the region. At Kasauli, about 22 kilometers northwest of Koti, the first fossil was found in 1864—just as the British were establishing Shimla as their summer capital. The ancient and the imperial overlap here in unexpected ways.

Heritage, Recognition, and Disaster

In 2007, the Himachal Pradesh government declared the railway a heritage property. That September, a UNESCO team spent a week inspecting the line. On July 8, 2008, the Kalka–Shimla Railway was inscribed as part of the Mountain Railways of India World Heritage Site, joining the Darjeeling Himalayan Railway and the Nilgiri Mountain Railway.

World Heritage status recognizes the railway as an outstanding example of innovative engineering solutions for mountain rail travel, as well as its scenic and cultural significance.

But mountains are not gentle custodians. During the 2023 North India floods, landslides washed out several sections of the line. The railway's 102 remaining tunnels—down from the original 107—testify to the constant battle between infrastructure and geology. Heavy monsoons regularly threaten the bridges and embankments. Maintenance is unending.

In winter, snow cutters are attached to the front of locomotives to clear the tracks. The railway operates in conditions ranging from monsoon deluges to Himalayan blizzards, with annual rainfall between 200 and 250 centimeters and temperatures spanning from freezing to 45 degrees Celsius.

A Journey, Not Just Transportation

The train averages 25 to 30 kilometers per hour. The railcar—a smaller, faster service—can reach 50 to 60 kilometers per hour. At these speeds, the journey from Kalka to Shimla takes several hours. This is not a limitation; it's the point.

The twenty stations along the route include Dharampur, Solan, Kandaghat, and the evocatively named Summerhill, just before Shimla. The track winds along the western side of National Highway 5 until north of Jabli, then crosses to the eastern side. Passengers watch the plains fall away below them as the train climbs through forests of pine and rhododendron.

The railway has drawn documentary filmmakers for decades. In February 2010, BBC Four aired Indian Hill Railways, a three-part series that devoted its third episode to the Kalka–Shimla line. The series won a Royal Television Society award. Anthony Bourdain featured the railway in the Punjab episode of Parts Unknown. In 2018, BBC Two's Great Indian Railway Journeys brought more viewers to these mountain tracks.

What draws them is not just the engineering or the history, but the experience itself: the slow revelation of the Himalayas, the clatter of wheels over a thousand bridges, the sudden darkness of tunnels and the explosion of light and green when they end.

The Chief Engineer's Legacy

Herbert Septimus Harington oversaw the construction as Chief Engineer. The chief contractor was Sujan Singh Hadaliwale. These names have largely faded from memory, but the line they built has outlasted the empire that commissioned it.

The railway's purpose has shifted entirely. No government relocates to Shimla each summer. The Viceroy is long gone. The Indian Army no longer needs the line for strategic transport. Yet the trains still run, climbing into the clouds just as they did when Lord Curzon inaugurated the service in 1903.

Today the railway belongs to the government of India under the Ministry of Railways. Northern Railway handles daily operations. But the passengers now are tourists and locals, not colonial administrators. They come for the journey itself—for the views, for the heritage, for the simple pleasure of watching mountains unfold outside windows that have framed these same peaks for over a century.

The railway was built to connect a summer capital to the rest of India. It succeeded in something greater: it created a way to experience the Himalayas at a human pace, close enough to touch the rock walls of tunnels, slow enough to watch eagles circle below you in the valleys. That experience—part engineering, part geography, part history—is what UNESCO recognized, what the documentarians seek to capture, and what keeps the trains climbing.

One hundred and two tunnels. Nine hundred and eighty-eight bridges. Nine hundred and seventeen curves. One mile of vertical rise. And still, after 120 years, the trains run.