Shinkansen might be fast but when you are in tunnels most of the time, it begins to feel a bit claustrophobic. I wondered why so many tunnels. See Google AI’s answer below. That “tunnel boom” is real!

“Japan’s mountainous terrain and the need for high-speed, efficient rail travel led to the extensive use of tunnels for Shinkansen lines, allowing trains to bypass difficult geography and minimize travel time.
Here’s a more detailed explanation:
- Mountainous Terrain:
Japan is a mountainous country, and Shinkansen lines often need to traverse or bypass these mountains for efficient travel. - Minimizing Travel Time:
Tunnels allow trains to go directly through mountains instead of winding around them, significantly reducing travel time. - Tunnel Boom Mitigation:
The high speed of Shinkansen trains can cause a “tunnel boom” as they enter and exit tunnels, so the trains are designed to minimize this noise and potential damage. - Aerodynamic Design:
The Shinkansen trains are designed with a long, streamlined nose to help reduce the effects of tunnel boom. - Seikan Tunnel:
The Seikan Tunnel, a major undersea tunnel, connects the island of Hokkaidowith the main island of Honshu, demonstrating the engineering feats required for Shinkansen construction. - Examples:
On the 500 km route between Tokyo and Morioka, there are nearly 120 distinct tunnels. - Safety:
Japan’s Shinkansen network is known for its safety, with no passenger deaths or injuries due to derailments. - Other Infrastructure:
Shinkansen routes also make extensive use of elevated viaducts to go over obstacles, further separating them from ground-based traffic”
When I first moved to LA I used to think about the freeway entrances as entering hyperspace. Then you drop out and you are someplace far away. Sounds like the trains might be a bit like that.
Still hoping for space and time portals