ETF ride systems has a sweet trackless system for dark amusement park rides (mostly). It uses metal strips and a proximity sensor in the same way to change speed, do 360 etc. by using binary commands. The cooler part is that the cars are guided by a buried electric wire with 2 sensors on the car that straddle the wire.

It actually does (can) compress the material. Yes, concrete is great in compressive and terrible in tension. So if you need a concrete section that needs to take tension, you make prestressed concrete and bias it towards the compression side. https://en.wikipedia.org/wiki/Prestressed_concrete Shotpeening works along a…