I believe almost all long distance high speed train proposals are based on land banking for future value increase, and nonsense like that. The actual social benefit agenda is secondary to an investment model which sees speculative rise in land and property value along the route at strategic locations with a very long tail, and the local and state tax outcomes which follow motivate agreements by authorities.

Instance in point: Brisbane Cross River rail. The economic impact statement is spectacular for land, rent, rate and building income. Same for intercity rail Sydney Brisbane Melbourne. For Brisbane, a state minister lost her job over a house purchase near a significant rail development (rightly or wrongly) but it's even explicit in economic modelling: they bank the future economic impact.