The high-speed rails were a public facility to help shuttles increase their speed and save their fuel.
While shuttles could fly in any directions freely, it had a huge consumption on the fuel. Also, when their speed was very high, particularly when they surpassed the speed of sound, accidents tended to happen too.
If hundreds of shuttles were soaring at the speed of sound, and two of them accidentally hit each other, there would certainly be dire consequences.
Therefore, in the "high zone" at the suburbs of the major cities of the Imperium of True Human Beings, convenient rails had been established, which could attract the shuttles to themselves with the electromagnetic force so that the shuttles could fly next to the rail. In such a way, the fuel could be saved, and the security could be greatly enhanced.