Steel Driver

Fuel economy-What if we replaced tires with steel train wheels?

50% of all energy produced by engines in cars/trucks, simply warms the tires. What if we rigged Semi-Trucks so that they could hop on train tracks, then hop off when they hit the right towns?

I'm not talking about containers, I mean to let the driver actually run his truck on a train-track, but use metal wheels instead of rubber tires.

It has already been invented. It was originally called piggy-back trains. Semi-trailers were transported on railroad flatcars. Now it is containerization or intermodal freight. Goods can be transported in the same container via truck, railroad, or ship. More efficient loading and unloading of freight. More effecient use of resources. We cannot build tracks to every place of business.