Feature request title:
Upgradeable Conveyor Belts
Allow for upgrading from normal speed conveyor belts to high speed
Why it should be implemented:
This will allow for easily changing your conveyor belt mains without having to demolish them first and slowing down your baggage loading/unloading. Similar to how you can change taxi foundation from grass to asphalt or concrete without demolishing the previous foundation.
Images, references or additional content: