I'm not an expert, but I've looked into this in the past when I was curious about it. There's quite a bit of working that goes into preparing and grading the l

I'm not an expert, but I've looked into this in the past when I was curious about it. There's quite a bit of working that goes into preparing and grading the land. There's also the added expense of building bridges and tunnels - with the speed a bullet train is travelling at, you want to avoid at-grade level crossings where road vehicles could get into the train's path. You also probably want side barriers to prevent cows and other large animals from wandering onto the tracks. This means you'll also need game tunnels or bridges to enable animals to get cross under or over the tracks, especially in wilderness areas. The Wikipedia article about TGV track construction [1] provides some helpful information[1]. Acquiring the land to build the track might also be expensive. Although governments have some power to expropriate land, there's often (usually?) significant cost involved. [1]https://en.wikipedia.org/wiki/TGV_track_construction#Preparing_the_trackbed https://en.wikipedia.org/wiki/TGV_track_construction#Prepari...