Switzerland built giant tunnels under the Alps to reduce truck traffic, but the project is now helping protect the country's mountains from climate threats

• Most people picture Switzerland's mountain tunnels as an engineering flex, a way to shrink travel time between cities.
• But the real story behind this vast underground network is less about convenience and more about climate.
• Since the 1990s, Switzerland has been quietly pulling truck traffic off its fragile Alpine roads and pushing it underground onto rail lines instead, a decision Swiss voters actually made themselves through a public vote.