Why dont tunnels collapse?

We all know the nursery rhyme about London Bridge falling down, but did you know that the London Underground is much stronger? The London Underground, also known as the Tube, has a rich history and its tunnels are known for their strength and safety. In fact, during World War II, people sought shelter in the Tube when German bombs were dropping on London.

But it’s not just the London Underground that is strong. Tunnels around the world provide safe transportation for thousands of people. For example, the Laerdal Tunnel in Norway is the longest road tunnel in the world, stretching 15.2 miles through a mountain range. The Marmaray Tunnel in Turkey is the longest underwater tunnel, connecting Asia to Europe over a distance of 47 miles. And the Seikan Tunnel in Japan is the deepest rail tunnel, reaching 800 feet below sea level.

Tunnels are also known for their unique features. The Tunnel of Love in Ukraine is formed by trees, while the Bund Sightseeing Tunnel in China is filled with colorful lights and music. And in Colorado, USA, the Eisenhower Tunnel holds the title for being the highest vehicle tunnel in the world, with an elevation of 11,013 feet.

Despite their impressive features, some people still have fears about tunnels collapsing. However, the likelihood of a tunnel collapsing is extremely low. Civil engineers work tirelessly to ensure that tunnels are safe and strong. They consider the forces of tension, torsion, compression, and shearing that tunnels have to withstand, as well as the weight of people and vehicles that pass through them. Strong materials like steel, iron, and concrete are used in tunnel construction to prevent collapse.

But even before construction begins, engineers conduct extensive planning to ensure the stability of the tunnel. They study the soil and rock types, water patterns, and nearby fault lines to determine the best digging and construction methods. This careful planning helps engineers build tunnels that won’t collapse.

The shape of a tunnel is also determined by the soil and rock conditions. Tunnels built in stratified rock, for example, may have flat roofs, as this shape provides more stability. Horseshoe-shaped tunnels or tunnels with Gothic ceilings are also common because these shapes are known for their stability.

In bigger tunnels, engineers use additional supports to increase the stability of the tunnel. For example, they utilize steel rock bolts to secure tunnels in rock. These bolts are drilled into the rock to prevent collapse and safeguard the tunnel. The amount of support needed varies depending on the type of rock and location.

Have you ever traveled through a tunnel? Next time, consider the effort put into making it safe for you. Whether it’s above ground, underground, or underwater, tunnels are constructed with your safety in mind. How can we make tunnels even stronger? Do you have any ideas?

Try It Out

Find a friend or family member to assist you with these activities:

– Explore some of the world’s most fascinating tunnels. Which one would you most like to visit? Explain your choice to a friend or family member.

– If there is a tunnel nearby, ask someone to take you through it. Then, write a story about your experience. If you can’t visit a tunnel, discuss with a friend or family member what you think it would be like. Then, create a fictional story about going through a tunnel.

– Discover more interesting facts about tunnels! What are the most intriguing facts you’ve learned today? Write a paragraph explaining what you’ve discovered and share it with a friend or family member.

Wonder Sources

– https://www.bbc.com/timelines/zxkrb82 (accessed 02 May 2019)

– https://www.popularmechanics.com/technology/infrastructure/g2559/the-worlds-20-most-impressive-tunnels/ (accessed 02 May 2019)

– https://practical.engineering/blog/2019/3/9/why-tunnels-dont-collapse (accessed 02 May 2019)

– http://umich.edu/~gs265/tunnel.htm (accessed 02 May 2019)

– https://science.howstuffworks.com/engineering/structural/tunnel.htm (accessed 02 May 2019)


1. What are the main factors that keep tunnels from falling down?

Tunnels are designed and constructed to withstand various forces that could potentially cause them to collapse. The main factors that keep tunnels from falling down include the strength of the materials used, proper engineering and structural design, and the support systems implemented during construction.

2. How are tunnels built to ensure their stability?

Tunnels are built to ensure their stability through a combination of careful planning, engineering, and construction techniques. The surrounding soil or rock is often reinforced with supports such as steel ribs or concrete linings to prevent cave-ins. In some cases, grouting or ground freezing may be used to stabilize the ground before tunnel excavation. Additionally, tunnels are designed with proper drainage systems to prevent water buildup, which could weaken the structure.

3. What happens if a tunnel’s stability is compromised?

If a tunnel’s stability is compromised, it could lead to serious consequences such as collapse or structural failure. This could result in blockage, damage to infrastructure, and potential harm to people inside or nearby the tunnel. Regular inspections and maintenance are essential to identify any signs of instability and address them before they escalate into major issues.

4. Are there any natural factors that can affect tunnel stability?

Yes, there are natural factors that can affect tunnel stability. Geological conditions such as the type of soil or rock, presence of groundwater, and seismic activity can all have an impact on tunnel stability. Engineers take these factors into consideration during the design and construction phases to ensure the tunnels can withstand these natural forces and remain safe for use.

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