Lateral upgrade: Rail Station X -> HS Rail X

[Elver]

Right now, when you get the HS Rail tech, you need to close down rail stations (with however many upgrades) and once they vanish replace them with HS Rail. Given that we're not replacing rail lines themself with HS rail lines, it feels off that all the infrastructure associated with a station must be scrapped then replaced rather than retrofitting HS into an existing infrastructure. Even if it's very expensive (e.g., Rail Station V -> HS Rail V could cost the difference between Rail I + Rail I->II->III->IV->V and HS Rail I + HSR I->II->III->IV->V), it would be less destructive to logistics networks than the current scrap-and-replace system.

If the argument is that the severe disruption is in lieu of replacing all the rails, that's a poor explanation since rail networks with few upgraded stations but thousands of km of tracks would hurt more than networks with shorter lines but complex stations - and the long-but-crude networks could avoid almost all disruption by building a few temporary rail stations just outside the cities that are being switched to HS rail.