For the record basically all of Shinkansen in Japan is new standard gauge rail, as "normal" trains in Japan are narrow gauge. And they still manage. In some pl

For the record basically all of Shinkansen in Japan is new standard gauge rail, as "normal" trains in Japan are narrow gauge. And they still manage. In some places you might have shinkansen, multiple private narrow gauge networks, metro and regular roads going through the same piece of land.