Problem with transfer

[miraceti]

Imagine following situation. You have a town A with a railway station somewhere on its periphery. One day, a bank grows up in this town. Lorry loading bays close to the bank accept valuables. Apparently, it is also possible to load valuables there. The railway station does not accept them and they are not waiting there either. Then, you have the second town B. For simplicity, its railway station is close to its center and there is a bank in this town too. The railway station in town B accepts valuables and it is possible to load them there too.

And now, how to carry the valuables from the bank in the town A to the bank in the town B _and_ back? The simplest scenario would be:
1) Trucks loads the valuables at the lorry loading bay close to the bank in the town A.
2) Trucks unload the valuables at the railway station on the periphery of the town A and mark them for transfer.
3) Trains load the valuables at the railway station of the town A.
4) Trains unload the valuables at the railway station of the town B. The valuables from the town A are delivered at this point.
5) Trains load the valuables at the railway station of the town B.
6) Trains unload the valuables at the railway station of the town A and mark them for transfer.
7) Trucks load the valuables at the railway station of the town A.
8) Trucks unload the valuables at the lorry loading bay close to the bank in the town A. The valuables from the town B are delivered at this point.

There is a problem in steps 2 and 7 because trucks can load the valuables which were unloaded at the same place from trucks (and not from trains). Therefore the valuables won't be delivered to the second city but will return to the stations were they have come from.

I can imagine two possible solutions right now:
1) Build two train stations in the first town and to use one for export and other for import. This is impractical. In a case of using planes instead of trains it would be very impractical - two airports take too much place and are expensive.
2) Carry the valuables from town to town by trucks directly. But I like trains more than trucks.

Am I correct or did I miss anything? I play OpenTTD just for a couple of weeks, may be I am totally wrong. This problem stopped my enthusiasm a bit since I feel it should be possible to solve this problem in a nice way. I did not try to solve the situation in the game yet but I think about it already three days.

If I am correct, I suggest an improvement of the game. Vehicle's orders cards should contain a new item in the "unload" menu next to "Unload if accepted", "Unload all", "Transfer", and "No unloading": "Transfer, no load back". This option would forbid to load cargo marked for transfer and comming from the same place the vehicle has just brought from and unloaded here. Warning! The vehicle can bring cargo also from several places or none. The option should forbid loading cargo comming from all places where the vehicle could load it since last "unload all" or "transfer" - even if it has actually brought nothing. Perhaps I should also emphasize that with this option selected, it should be possible to load the same type of cargo but comming from other places or not marked for transfer at all.

[Alberth]

There is a problem in steps 2 and 7 because trucks can load the valuables which were unloaded at the same place from trucks (and not from trains). Therefore the valuables won't be delivered to the second city but will return to the stations were they have come from.

I skipped most of the text, but if this is you problem, you are correct. This is what happens in OpenTTD.

1) Build two train stations in the first town and to use one for export and other for import. This is impractical. In a case of using planes instead of trains it would be very impractical - two airports take too much place and are expensive.
2) Carry the valuables from town to town by trucks directly. But I like trains more than trucks.

1 will work. It is also suggested at the wiki (search for 'feeder systems').

A third option is to play cargo-dist. That is a patched OpenTTD version, which gives cargoes a sense of destination. In that way, cargo you just unloaded won't hop back on board. You can find cargo-dist in the OpenTTD development forum.

If I am correct, I suggest an improvement of the game. Vehicle's orders cards should contain a new item in the "unload" menu next to "Unload if accepted", "Unload all", "Transfer", and "No unloading": "Transfer, no load back". This option would forbid to load cargo marked for transfer and comming from the same place the vehicle has just brought from and unloaded here.

Does not work. Imagine three places A, B, and C, and three trains A<->B, B<->C, C<->A. Cargo can spin around forever.

[miraceti]

1) Build two train stations in the first town and to use one for export and other for import. This is impractical. In a case of using planes instead of trains it would be very impractical - two airports take too much place and are expensive.
2) Carry the valuables from town to town by trucks directly. But I like trains more than trucks.

1 will work. It is also suggested at the wiki (search for 'feeder systems').

Here?

A third option is to play cargo-dist. That is a patched OpenTTD version, which gives cargoes a sense of destination. In that way, cargo you just unloaded won't hop back on board. You can find cargo-dist in the OpenTTD development forum.

Is there any chance that this patch will become a part of official OpenTTD release?

If I am correct, I suggest an improvement of the game. Vehicle's orders cards should contain a new item in the "unload" menu next to "Unload if accepted", "Unload all", "Transfer", and "No unloading": "Transfer, no load back". This option would forbid to load cargo marked for transfer and comming from the same place the vehicle has just brought from and unloaded here.

Does not work. Imagine three places A, B, and C, and three trains A<->B, B<->C, C<->A. Cargo can spin around forever.

This is a bit different but, of course, very closely related problem. You are right, it would not help in such a case. However, I think my proposal could be implemented for simple cases too.

[Eddi]

A third option is to play cargo-dist. That is a patched OpenTTD version, which gives cargoes a sense of destination. In that way, cargo you just unloaded won't hop back on board. You can find cargo-dist in the OpenTTD development forum.

Is there any chance that this patch will become a part of official OpenTTD release?

There is a chance, but to my knowledge there are still unresolved issues, so don't expect it "soon". Maybe for 1.1 (in about a year), maybe not.

[kamnet]

Here's an easy way to solve your issue, assuming you have enough space:

[Alberth]

1 will work. It is also suggested at the wiki (search for 'feeder systems').

Here?

Actually, one page further: Two way feeder service.

Does not work. Imagine three places A, B, and C, and three trains A<->B, B<->C, C<->A. Cargo can spin around forever.

This is a bit different but, of course, very closely related problem. You are right, it would not help in such a case. However, I think my proposal could be implemented for simple cases too.

Sure it could. It will take less than a week before we get a bug report that for some less-simple case it fails. Then what?
Since your algorithm does not cover such cases, the only way out is to throw your algorithm away, and design and implement one that really works.
I believe time is better spent by designing a proper generic solution in the first place.