I don't know the full list of requirements, but a route has been chosen, some number of federal approvals have been granted, some regulatory hurdles passed, and supposedly two federal approvals remain.
The route is easier (engineering and cost-wise), due to geography, than the California rail, or anything in the Eastern corridor, and to keep it even easier they're running it along existing utility corridors where possible to further reduce the amount of private land access they have to contend with:
https://www.texastribune.org/2019/05/15/texas-bullet-train-a...
I don't know the full list of requirements, but a route has been chosen, some number of federal approvals have been granted, some regulatory hurdles passed, and supposedly two federal approvals remain.
The route is easier (engineering and cost-wise), due to geography, than the California rail, or anything in the Eastern corridor, and to keep it even easier they're running it along existing utility corridors where possible to further reduce the amount of private land access they have to contend with:
https://www.texascentral.com/alignment-maps/