vc-labs opened the ticket and wrote:

[Not actually the feature request yet, just a propasal for discussion among OTTD Gods]

Any TT player knows that hustle, which comes up when it's time to upgrade any heavy-loaded airport, or to re-built overloaded multi-platform station (sometemes it's even connected, when the station locked to that airport).
If you have second airport in town, you may try to catch all upcoming planes and re-rote them to second port (and then - back, after re-building the airport). Or you can send them to depot in departuring ports (still problem with airborn ones already enrouting to your port). You can send all planes, binded to that damned port, to depot, and sell ones which landed in that port (waste of money and service). But all that eats your gametime and money.

I suggest to implement Out-Of-Service feature for all types of stations (I realise, it's not a one-minute job, given it should affect the vehicle's behavior, but maybe somewhen in far-away releases it could be done).

How it should work if you close the station (set it Out-Of-Service):
Any wehicle enrouting FROM the closed staion should not be affected. No locks, no delays.
Any vehicle enrouting TO closed station (except planes) should follow to the next depot on the way and locked there until the station will come back to service.
Airports should have a bit different behavior (given there're no any depot on the way).
No any planes, departing from closed airport, should be locked or delayed (same as for stations).
Any grounded planes, which are about to depart to closed port, should be sent to depots in these ports and locked there as soon as they unload passengers from previous flight (already re-loaded go to depot as it). Or, for simplification, all of them may go to depot after re-load. The plane should request the destination port (closed or not) twice: before starting to load cargo, and before leaving the terminal (or just before leaving, if simplified, but that will affect revenue, given the cargo will be locked with plane, and the payment for upcoming ride will drop down).
[In case you'll somewhen implement the request about vehicles not to go to depot loaded, the simplified behavior will be quite enough]
Any airborn planes, enrouting to closed port, should be accepted by closed port, and allowed to use depot for service and permited to take-of.
As soon as no one binded vehicle will be left on the closed station or enrouting to it, the station (or airport) sends the message (pop-up) to player that it came Out-Of-Service, so the player may start to re-build it.
As per vehicles, which stay on the closed station under "Full Load" order, - they should load whatever left on the station (already in stock) and be forced to preceed to next point, not waiting the stock to be re-filled.

In addition, i'd suggest one extra feature for closed stations. They shouldn't be accounted in company rating.
Then, if you want to build the station ahead, for future development, you may do it and set out-of-service right away, not aware, that the town will refuse you to resume defelopment few years later.

There is one more annoing problem will be automatically resolved by Out-Of-Service feature.
Currently, when you temporary demolish station in order to re-buid it (upgade airport, FE), there're a lot of messages pops up about vehicles with "invalid order". Given all vehicles, enrouting to closed station, will be stopped in depots at the moment of station' demolition, these messages will not come out (if I correctly understand current AI behavior).

This feature may also help if you want to demolish overloaded station forever. First you close it, then - sell or re-route all stopped vehicles, and then - demolish. Unfortunatelly, in this case part of vehicles will be stopped in depot loaded. Not a big deal, meanwhile, - you loose more, catching'em after unload and sending to depot one-by-one (because it eats your gametime).

Unfortunatelly, this Out-Of-Service algorithm still looks wet for me (it doesn't cover all possible situations, where it might be needed). So maybe some folks already thought about this feature and could offer better one?.. But I'm quite certain that Out-Of-Service feature would be welcome by a lot of players.

Reported version: trunk
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/1292