Building the Chenab Bridge – How did India Achieve the Impossible?

Far away from mainland India, in the Reasi district of Jammu and Kashmir, India managed to achieve the impossible. High in the sky, 1315 meters to be precise, a steel and concrete bridge has been laid out by the Indian Railways across a river gorge. This is an engineering marvel like nothing else on planet Earth.

Experts are already calling this mega project a ‘next-to-impossible’ human-made feat. This is the story of the Chenab Bridge. Here, we are going to learn about the myriad challenges faced by engineers and construction workers in building this bridge, and how its design had to be altered from conventional norms to fit the unique topography and geography of that area.

Last year, in June 2025, the world’s highest arch bridge was inaugurated in Jammu and Kashmir. It is located between the Kauri and Bakkal rail stations on the Jammu-Baramulla line. It has been constructed for the ease of travel between Jammu and the Kashmir valley. The NH44, which remained the main traveling route between the two places are usually always covered in snow.

Therefore, constructing this bridge became a necessity. Officially regarded as the highest rail bridge in the world, the construction of this 169-meter-long bridge, which cuts quite literally through a mountain, was a hellish and nightmarish concept. It was brought to fruition against all odds.

Overall, the 272-km Udhampur-Srinagar-Baramulla Rail Link project, which includes the Chenab Bridge, features 943 bridges and 7 tunnels. It took a total of $5 billion to construct this massive project. But even with this cost, it couldn’t alter the natural challenges that the construction workers, engineers, and designers were about to face.

In the Reasi district, deep in the foothills of the Himalayas, temperatures vary widely. From freezing cold temperatures that even drop down to 0 or below, to 50* Celsius across the year in winter and summer months, Reasi can be a challenge for any engineer to estimate the right temperature. But in terms of challenges in the area, that’s just the tip of the iceberg.

Getting to the Chenab bridge site was a problematic scenario in itself, let alone the headache of transporting 30,000 tons of steel so high up in the valley. Here, the steel isn’t transported after being pre-manufactured in a factory like in any other construction site. Due to the high altitude, rugged terrain, and tough topography, they essentially come in flat plates to the construction site. At the site itself, they are welded and manufactured for construction.

To begin with, one of the big problems in choosing the design material, i.e., steel, is that steel can expand and contract in extreme temperatures. The higher the temperature (up to 50* C), the more expansion, and the lower the temperature, the steel contracts.

This shift in the main and the only material’s length and volume can be a real pain for designers to come up with a universal solution.

A bigger problem was that, since the bridge is built over a canyon so high up in the sky, the sunshine doesn’t fall on all regions equally and proportionally. This means that the bridge doesn’t receive the sunlight in equal proportions. This can expand certain areas while keeping the other areas intact. Since it was being built for trains to pass over it, the instability in the bridge’s tensile strength could have been a huge problem.

Since temperatures, no matter how extreme, are a natural phenomenon, nothing could have done about that. But those working on the project found a way around it. They pre-stressed the rails upon which the train would move.

They have pulled really tight for stability. They are also allowed to move freely of their fixings on the bridge. This is an ingenious design innovation that solved a huge problem.

The fixings that are on the bridge have the rails sitting on them. But the design ensures that they aren’t actually attached. This allows the rail to move back and forth as the bridge expands and contracts. Besides snow and the sun, there’s another big player from Mother Nature that serves as a bigger problem – Wind. The canyon can experience gusts up to 165 miles per hour.

The wind is a big factor in this region due to a phenomenon called ‘The Venturi Effect.’ A concept in fluid dynamics, the Venturi Effect ensures that the fluid velocity increases and static pressure decreases as it flows through a constricted section of a pipe or nozzle. The same is true for wind in a constricted section/area.

A narrow passage, such as a canyon in this Reasi region, effectively becomes a funnel. As wind passes through, its pressure drops and speed increases. This creates a powerful and chaotic pattern that’s near-impossible to predict.

Therefore, to test the design of the bridge and its ability to withstand such fast and chaotic wind patterns, designers created a model scale of the structure indoors to a 1:50 ratio, and the scaled-down version was put to the test in a wind tunnel.

Despite such tests, the unique and challenging topography called for some more drastic research. The design team then did some localized tests, both physical and computational, remodeling the hills, the valleys, trees, and every other geographical feature around it.

Only then could they accurately calculate the accelerated flows locally. There is an acceleration of wind speed in such high terrains. A wind speed of 40-50 meters per second could turn into 48-60 meters per second up there.

The studies considered those arbitrary factors as well, since they were very important to the design of the bridge.

The Canyon’s natural V-shape was also a challenge that the designers had to factor in. If you stick a tower to one side of the V-shape, especially the one that has unstable rocks on its surface, there’s a tendency for that tower to want to slide down that valley.

The solution – The Chenab Bridge is an arch design

It starts from the two opposite ends, and both sides meet in the center, creating a locked-shape pattern. As they meet in the middle, the two sides push against each other and force their weight down through their legs and into the sides of the mountain. This way, even if the towers tend to slide into the mountain’s side, they will happen simultaneously. This will ensure balance, equal distribution of strength, and a design that will withstand the brutal forces of time.

When the supporting towers are erected, that’s when the top deck comes into play. The top deck is a flat piece of the bridge that’s constructed on sections. Basically working from each side of the canyon, a piece of the bridge deck is laid, then another piece is put in behind it, and then another piece behind it, and so on. Gradually, this pushes the bridge deck across the canyon until the two sides meet in the middle. This is called a ‘“Launch Methodology.”

Earthquakes are a persistent issue in the Chenab valley, but since the bridge is so big and long (359 meters above the river bed and 1.3 km long), it reduces the earthquake’s forces to a bare minimum.

Designed by the WSP Team in Finland, the Chenab Bridge is a true man-made construction marvel