Beneath the Saint-Gothard mountain range in Switzerland, two parallel railway tunnels, each 57 kilometers long, stretch through the Alpine rock at depths of up to 2,300 meters. Managed by AlpTransit, this base tunnel holds the title of the world’s longest railway tunnel. Construction, which took 17 years, involved removing 28.2 million tons of rock—equivalent to five times the volume of the Great Pyramid of Khufu in Egypt. Engineers encountered extreme heat, reaching up to 45 degrees Celsius during excavation. To manage this, large fans and refrigeration systems were deployed to bring temperatures down to 28 degrees Celsius, the safety limit set by the Swiss Accident Insurance Fund (SUVA). The geological conditions posed another challenge, as the exact composition of the rock was unknown before excavation began. Teams had to adjust their methods in real time, using tunnel boring machines or explosives depending on the rock's hardness. Some of the extracted rock was crushed and reused as aggregates in the concrete lining the tunnel. The remaining material was dumped into Lake Uri, near the mouth of the Reuss River. Plans are in place to create two groups of wild islands and restore shallow water zones to support local wildlife and improve biodiversity. The tunnel was designed to reduce road traffic in the Alps by offering a faster and more efficient transport option. It cut the travel time between Zurich and Milan from 3 hours 40 minutes to 2 hours 40 minutes. However, according to the Federal Office of Transport, in 2024, 960,000 heavy trucks still used Alpine routes—far above the target of 650,000 set by the Alpine Initiative in 1994. Despite this, the tunnel has boosted rail transport for both passengers and freight, especially in its early years. The share of rail transport for passengers once exceeded 70%, though it slightly declined to 68.6% in 2025. Completion of German access points on the northern side of the tunnel is still pending.