Factorio Forums

If signs would be placed like that, AC or BC or D or none rules should be added based on the train's route.
All rules should be applied for entering segment, not leaving or passing. Even if the sign is far far away.
If train somehow entered segment already (manual, forced, sign change etc) any sign can be passed.

ssilk wrote: ↑

Wed Nov 04, 2020 7:13 am

- if no filter is set, but the penalty, the penalty is added to every train, that passes this signal in the pathfinder algorithm. If filter and penalty is set, the penalty is only added, if filter is true. If no penalty is set, but a filter, a very high penalty is added.

"very high penalty" is bad. It will surprise you in bad ways.

And I want to add couple of things:

• Sign give logic signal when train pass (even if it's rules applied at another moment)
• Sign can make passing train whistle

Sounds also as a good enough solution. I like it. Eventually it’s difficult to find out where this begin of such a segment is. But I think this can be done.

So we have several solutions how this might work.

I don’t know, but for me this suggestion is in a state, where a product owner can take it and discuss with the programmer. Or boskid might say, what’s missing from his sight.

ssilk wrote: ↑

Thu Nov 05, 2020 8:03 am

Eventually it’s difficult to find out where this begin of such a segment is.

Nearest signal of course.

Also it would be worth mentioning: On bidirectional tracks sign has effect in one direction only. For other direction player can use second sign.

I'm failing to see the use for this.

• Filter trains by fuel or cargo: What's the use? It would be real nice to be able to control where a train goes next based on its state, but using conditional signals doesn't let you change where the train is going, only how it gets there.
• Route trains away from a high-traffic area: We already have the option to do this; passing a train station which is not the train's current destination adds a pathfinding penalty of 2000 squares, even of the station doesn't have any trains assigned to it.
• Filter trains by length: Useful, but inferior to the suggestion this is supposed to be an alternative to; filter signals would allow you to keep long trains out of areas which are not built to handle them, but the improvement to chain signals would allow them to safely use those areas.

Let's try to see:

• This is a long way without fuel supply. Do not even enter without X GJ fuel.
• Base heart has so much traffic. Ore trains are not allowed.
• Long train would wait so long it's way out of here. Better not allow it to enter.

In general reason is the same as the reason we have to choose place for each signal. Human design work better here.

Sad_Brother wrote: ↑

Thu Nov 05, 2020 4:20 pm

• This is a long way without fuel supply. Do not even enter without X GJ fuel.

And then what happens? The train has to stop somewhere to pick up more fuel. If the next stop in the schedule is too far away to make it, what is is supposed to do? If the filter signal is an absolute barrier, then the train is stuck at the previous stop with 'No Path'; if the filter signal is just a pathfinding penalty, the train heads there anyway, except maybe it takes an even longer route to avoid the signal.

Sad_Brother wrote: ↑

Thu Nov 05, 2020 4:20 pm

• Base heart has so much traffic. Ore trains are not allowed.

That could be somewhat useful, but not extremely so; the pathfinder algorithm already has penalties for other trains, so if your base is heavily trafficked then trains that don't need to go there will generally avoid it anyway.

Sad_Brother wrote: ↑

Thu Nov 05, 2020 4:20 pm

• Long train would wait so long it's way out of here. Better not allow it to enter.

Under what sort of scenario have you actually had this problem? I've had trouble with long trains causing delays, because they pass through an intersection but then end up waiting at another red signal with the back of the train still blocking the first intersection, but they don't take any longer to reserve a path for themselves. (Now, if the 'Chain signals reserve space for train to exit' suggestion were implemented, that would change, since longer trains would have to reserve more space before proceeding, but the pathfinder already has provisions for looking for an alternate route if a train spends too long waiting at a chain signal.)

macdjord wrote: ↑

Thu Nov 05, 2020 7:52 pm

The train has to stop somewhere to pick up more fuel.

Train can choose other station with that name. With fuel supply. For example.

macdjord wrote: ↑

Thu Nov 05, 2020 7:52 pm

the pathfinder algorithm already has penalties for other trains

Yes. But you may want to reserve some tracks for more important delivery to be faster. For example.

macdjord wrote: ↑

Thu Nov 05, 2020 7:52 pm

Under what sort of scenario have you actually had this problem? I've had trouble with long trains causing delays, because they pass through an intersection but then end up waiting at another red signal with the back of the train still blocking the first intersection, but they don't take any longer to reserve a path for themselves. (Now, if the 'Chain signals reserve space for train to exit' suggestion were implemented, that would change, since longer trains would have to reserve more space before proceeding, but the pathfinder already has provisions for looking for an alternate route if a train spends too long waiting at a chain signal.)

I did not because all my trains are short. But look. (If that doubtful chain signal suggestion would be implemented):
Your long train wait at the intersection. Signals ahead should be green but not for such long train. This train wait more but other shorter train may use this path and this train wait more and more. Or other train cannot use and they wait together. Several such intersections nearby and your trains wait each other. And you cannot forbid pathfinder to send long trains here because this suggestion voted less and was not implemented.

macdjord wrote: ↑

Thu Nov 05, 2020 3:30 pm

Filter trains by fuel or cargo: What's the use? It would be real nice to be able to control where a train goes next based on its state, but using conditional signals doesn't let you change where the train is going, only how it gets there.

Trains by fuel was already discussed in this thread; it makes not so much sense to check for stuff, that can change during the travel.

Currently this has split in two basic streams. One that will add just penalty, the other that disallow routing based on segments.

Trains by cargo: well, if you really can close a path (not only add penalty) this can be used to control, which unload station should be used for types of cargo. Or with added penalty you can say: this unload station is nearly full, use another.

In the end I admit, that this is just another option. A more thoughtful list of things is in the paragraph with the italics here: viewtopic.php?p=519066#p519066

Route trains away from a high-traffic area: We already have the option to do this; passing a train station which is not the train's current destination adds a pathfinding penalty of 2000 squares, even of the station doesn't have any trains assigned to it.

I know, but that is really ugly. It feels totally broken.

Filter trains by length: Useful, but inferior to the suggestion this is supposed to be an alternative to; filter signals would allow you to keep long trains out of areas which are not built to handle them, but the improvement to chain signals would allow them to safely use those areas.

I thought that suggestion was already discussed and there where too much issues with it.

ssilk wrote: ↑

Fri Nov 06, 2020 8:41 am

I thought that suggestion was already discussed and there where too much issues with it.

That is the exact opposite of true:

boskid wrote: ↑

Tue Nov 03, 2020 8:38 am

Honestly previous topic about chain signals taking into account the train length was easier in terms of possible implementation. This however could have more possible use cases.

[snip]

This idea is not mature enough to be even considered to implement.