The Bullet Train's Nose Was Designed by a Bird

The first Shinkansen ran on October 1, 1964, nine days before the Tokyo Olympics opened. It covered the 320 miles between Tokyo and Osaka in 4 hours instead of the previous 6 hours 40 minutes, hitting 130 mph. The world had never had a train that fast. Today's N700S series cruises at 186 mph and the line has carried over 10 billion passengers without a single fatality from a derailment or collision.

The trains got faster, and a problem appeared. When a train hits about 170 mph and enters a tunnel, the air it pushes ahead compresses into a wave that exits the far end as a sonic boom. Residents near tunnel mouths in mountainous Japan were filing complaints. The fix had to slow the air without slowing the train.

The engineer who solved it, Eiji Nakatsu, was a birdwatcher. He noticed that kingfishers dive from a low-density medium (air) into a high-density medium (water) without splashing — their long, tapered beaks part the water rather than slap it. The 500-series Shinkansen, introduced in 1997, got a 50-foot-long nose modeled after the kingfisher's beak. The boom went away. The train also drew 15 percent less electricity at the same speed.

The other constraint nobody outside Japan really thinks about is the country's geology. Japan is on the Pacific Ring of Fire and a major Shinkansen route runs through some of the most seismically active land on Earth. The system uses a network of seismometers along the line that detect P-waves — the small fast tremors that arrive seconds before destructive S-waves — and cut power to trains automatically. In the 2011 Tohoku earthquake, every Shinkansen in motion stopped safely before the shaking arrived.

A train that fast, in that landscape, with that safety record, is what happens when the constraints are taken seriously by people who watch birds.