> Japan has multiple train companies operating different networks, so a separate network was the only thing they could build The Shinkansen initial network an

> Japan has multiple train companies operating different networks, so a separate network was the only thing they could build The Shinkansen initial network and separated tracks have been built at an age where JRails was still a single centralized company. The main reason was to create a network with a focus speed and punctuality. And to be fair, it was the right choice and pretty revolutionary at the time.