# Why They Built The World’s Longest Rail Tunnel

Source: https://www.youtube.com/watch?v=iJqXFUDB66k
Recap page: https://rapidrecap.app/video/iJqXFUDB66k
Generated: 2026-05-28T14:32:52.12+00:00

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## Quick Overview

Switzerland built the Gotthard Base Tunnel to bypass the difficult and dangerous Gotthard Pass, enabling efficient high-speed and heavy-cargo rail transit directly through the Alps at sea level. This massive infrastructure project, the longest and deepest rail tunnel in the world, reduced travel times and shipping costs significantly while overcoming extreme engineering challenges like high temperatures and ground water pressure.

**Key Points:**
- Switzerland completed the 35-mile (57km) Gotthard Base Tunnel as the world's longest and deepest rail tunnel.
- The tunnel allows high-speed passenger and heavy cargo trains to travel through the Alps at near-sea-level elevation.
- Engineers divided the construction into five simultaneous sections to complete the project efficiently.
- Tunnel boring machines successfully excavated through dense granite and gneiss rock, which is nearly impossible to dig through using conventional methods.
- The project required a total investment of $12 billion, funded by Swiss taxpayers.
- The final alignment of the tunnel deviated by only 3 inches (8cm) horizontally and 0.4 inches (1cm) vertically.

![Screenshot at 00:27: Map showing the direct 57km path of the Gotthard Base Tunnel connecting Erstfeld and Bodio beneath the Alps.](https://ss.rapidrecap.app/screens/iJqXFUDB66k/00-00-27.jpg)

**Context:** For centuries, the Swiss Alps served as a major barrier to transportation between northern and southern Europe. The only route, the Gotthard Pass, was a treacherous, high-altitude passage that was frequently closed by snow for seven months of the year. The Gotthard Base Tunnel was conceived as a permanent solution to this logistical bottleneck, fundamentally changing European rail commerce by providing a direct, reliable, and high-capacity link through the mountains.

## Detailed Analysis

The Gotthard Base Tunnel project represents a monumental achievement in civil engineering, designed to solve the chronic transportation issues caused by the Swiss Alps. The tunnel runs 57 kilometers (35 miles) through the base of the mountain range, maintaining a low elevation that prevents the weather delays and steep gradients associated with the historical Gotthard Pass. Construction was divided into five distinct sections, allowing work to proceed simultaneously. Due to the extreme geology, including high-density granite and gneiss, engineers employed specialized tunnel boring machines capable of generating 27 million newtons of force to shatter the rock. Safety features include two parallel tubes and 178 cross-passages for emergency access. Despite the enormous scale, the project achieved incredible precision, with an alignment deviation of only a few centimeters across the entire 35-mile length. The tunnel successfully facilitates modern, high-speed rail travel, marking a transformative shift in European logistical infrastructure.

### Historical Challenges

- The Gotthard Pass required up to 7 days to cross by mule
- Heavy snow blocked passage for 7 months annually
- The 1880s dynamite tunnel only partially solved transit limitations

### Engineering Solutions

- The tunnel maintains a low elevation to allow high-speed and heavy cargo trains
- Two main tubes and 178 cross-passages ensure safety
- Advanced ventilation systems mitigate ambient temperatures reaching 115°F

### Construction Methodology

- The 35-mile route was divided into five simultaneous work sections
- Tunnel boring machines exploited the low tensile strength of granite and gneiss
- Vertical shafts and access tunnels were required to reach deeper mountain segments

### Project Precision

- The entire tunnel achieved a horizontal alignment deviation of only 3 inches (8cm)
- The vertical alignment deviation measured a mere 0.4 inches (1cm)
- Construction finished after over a decade of complex logistical coordination

![Screenshot at 00:52: Steep, winding roads of the historical Gotthard Pass illustrating the difficulty of mountain transit.](https://ss.rapidrecap.app/screens/iJqXFUDB66k/00-00-52.jpg)
![Screenshot at 03:00: Diagram displaying the tunnel's twin-tube design and emergency cross-passages for safety.](https://ss.rapidrecap.app/screens/iJqXFUDB66k/00-03-00.jpg)
![Screenshot at 04:26: Side-by-side comparison of tunnel boring machine components used to excavate the rock.](https://ss.rapidrecap.app/screens/iJqXFUDB66k/00-04-26.jpg)
![Screenshot at 05:53: Cross-section graphic showing the 2,700-foot vertical shaft required to access the deep Sedrun section.](https://ss.rapidrecap.app/screens/iJqXFUDB66k/00-05-53.jpg)