What does an interchange do?
After a couple weeks, I got an upgrade option that says "Upgrade one station to an interchange". What does an interchange do and when should I upgrade a station to one?
From the patch notes (emphasis mine):
The possible upgrades are railcar (same as before), railcar speed upgrade (all railcars increase in speed), platform upgrade (all stations increase in capacity), interchange (upgrade one station to hold 18 passengers, and load / unload at 4x speed), extra tunnels (two extra tunnels).