The Hindenburg tragedy put an end to the flourishing era of transatlantic passenger flights by airships. History is littered with mass transit ideas both great and small that failed because they were either too crazy or succumbed to the realities of financing and technical challenges.
Can you imagine a recumbent cycle crossed with a monorail? A bus which allows cars to drive under it? A propeller plane zipping along on a rail? What about a bike railway? Someone did.