Routing restriction discussion

[m3henry]

squishycube: what monorail tracks are you using?

[squishycube]

pff, not sure. They are from the time there still were .exe's modifying the game's graphics. They were intended to look like TTO's monorails.

They are here: http://www.tt-forums.net/viewtopic.php? ... il&start=0

But I see now that mine are even different from those, maybe I decided those didn't do so well after all and changed to even other graphics. I don't remember...

[Deblaauwn]

Maybe something else that could be implemented: a track speed restriction, just like in real life. Maybe it might work to 'release the pressure' on busy junctions if trains could pass them at a lower speed.
This feature should not be like 'filter fast trains' (that is already implemented with train top speed) but just something that lets trains proceed at lower speeds.

[Ameecher]

Maybe something else that could be implemented: a track speed restriction, just like in real life. Maybe it might work to 'release the pressure' on busy junctions if trains could pass them at a lower speed.

That would surely put more pressure on the junction and it's surrounding area, if trains slow down then you'll more likely get queues and the junction would be blocked for longer. Ideally you want as fast a junction as possible.

[SuperTycoon]

Maybe something else that could be implemented: a track speed restriction, just like in real life. Maybe it might work to 'release the pressure' on busy junctions if trains could pass them at a lower speed.

That would surely put more pressure on the junction and it's surrounding area, if trains slow down then you'll more likely get queues and the junction would be blocked for longer. Ideally you want as fast a junction as possible.

It might be useful for creating speed-limited tracks through towns, for realism. Or restricting the speed for other realism reasons (preventing a short burst of acceleration between two slow bridges for example)

The problem with implementing this (if I remember past discussions correctly) Is that the speed can be restricted for one tile (with the signal on it) but will immediately begin to accelerate again, since there is no way of defining when the restriction is to end. However, with PBS this may work, since the train is looking ahead, and therefore the duration of the restriction (to the next signal) can be more easily defined. Long stretches of speed-restricted track using PBS would eat up processor time though.

[Deblaauwn]

I thought of it again, I think Ameecher is right. But another speed-restricting feature in real life is 'orange' signals through which trains can pass slower, for example if the next signal is red. To work optimal, all (standard) signals should work like this

[Deblaauwn]

I discovered a bug in 2.6 r 1576
In the attached screenshot you see a station with one terminus for a local train, and two through platforms. The approaching train is a local service from Puntburg-Slundington. The other platforms are used by through trains.
To make sure only the local train goes to the terminus, I use the routing restrictions 'station of next order IS Slundington'. For the other two platforms the argument is 'IS NOT Slundington'.

The bug: this train cannot reverse safely. In the attached savegame, watch the local train approach, load and then stop with this message.
When you remove the restriction from the upper signal, the bug doesn't exist anymore, but in that case it might be possible for through trains to get to that platform as well, which should be avoided.

[Vloris]

To make sure only the local train goes to the terminus, I use the routing restrictions 'station of next order IS Slundington'. For the other two platforms the argument is 'IS NOT Slundington'.

At both those restrictions, you can 'Or' them with "station last visited is Puntburg Airport' to allow trains that are already on the station to exit it.

But I think it should not be necessary, because a train that can only find one route, and that's a dead-end it will still take it.

[Caelan]

Very nice work indeed! Looking forward on using this. It greatly anhances gameplay as i now can direct trains more exactly where they have to go. I would appreciate the wiki to explain how I have to get it to work though. But thanks for the nice feature!

[JGR]

But I think it should not be necessary, because a train that can only find one route, and that's a dead-end it will still take it.

This is not necessarily true for PBS signals, and is a perpetual problem in my game.
If the train cannot find a way past a PBS signal, it will just sit there, even if the light is green. This can occur if the train is completely lost or has found it's way to a restricted PBS signal.
This is due to the way in which the PBS route finder is implemented.

Using a distance from signal criteria is possible to alleviate this, as this works well with PBS blocks, as the route is decided upon entry of the block only.

I think that if a train waits at a green PBS signal for more than x days (or at all), a message should pop up, but I'm am currently too busy to implement something like this, which requires a better understanding of the PBS system...

JGR

[Deblaauwn]

[... you can 'Or' them with "station last visited is Puntburg Airport' to allow trains that are already on the station to exit it.

That's right, when I add this 'or' the train will reverse safely, but the restriction is not needed as long as that terminus is the only non-restricted option for this train.
The restriction might become useful if there are so many trains on the mainline that sometimes the whole station is full.

[MJS]

Why would you think it's not necessary? I'd say the moment the train leaves station P, the current order becomes S and the next order P - so that it doesn't fulfill the criteria any more. Or am I wrong there?

[Deblaauwn]

Maybe I did not say clearly what I meant: you can restrict the two through signals and leave the terminus signal untouched, since the trains heading for that terminus will not take the through platforms anymore.
In case the amount of mainline traffic grows through trains will also take the terminus, so then it will be time to restrict that one as well..

[bit OT?] Anyway, I don't like all signals on a route to be restricted, because in that case a train that should not be there will just stop in front of the signal so I always try to leave at least one exit unrestricted, since then 'wrong' trains can proceed and eventually find the right way to their station.

[Deblaauwn]

1. If the train is 'blocked' by a restricted signal it just rolls straight past regardless.

The route tracing restriction only 'discourages' a train from choosing to use that particular track by effectively telling the routefinder that it is a dead end. A train can still roll past quite happily even if the restriction supposedly blocks it, if it can find no route.

I saw this on page 6 of this thread. I believe this is not true. I used to have a station with a routing restriction for food, later I rebuilt the station with a separate checkpoint for food trains (they were longer) but I left the restricted signals. Often the trains would not take the right exit and go to that station again, of course without going through the checkpoint. Next they come to the signals with the restriction 'no food' and just stop in front of it.

The train with the red circle is a food train, halted in front of a PBS entry. Those exits are restricted, but he could just pass through it since there are several empty platforms.

This station works properly without those restrictions.

[JGR]

But I think it should not be necessary, because a train that can only find one route, and that's a dead-end it will still take it.

This is not necessarily true for PBS signals, and is a perpetual problem in my game.
If the train cannot find a way past a PBS signal, it will just sit there, even if the light is green. This can occur if the train is completely lost or has found it's way to a restricted PBS signal.
This is due to the way in which the PBS route finder is implemented.

See my previous post.

The train with the red circle is a food train, halted in front of a PBS entry.

To get a better idea of why your restrictions aren't working, we need a savegame or a specific restriction set posted.

JGR

[Deblaauwn]

I'm sorry, I did not check that post.

The four exit signals for the short platforms are restricted 'Train Cargo is not Food'.
With this station layout, the restriction is useless, but first I had no waypoint and the 'long' entry connected to the others, resulting in food trains blocking the junction if their two platforms were in use.

I should have removed the restriction after rebuilding the station. It is not a bug, just my ignorance.

[steelixb]

I have a problem where it seems appropriate to have bi-directional track. This of course means that two trains could end up wanting to take the same track at opposite ends, with neither train knowing about the other.

A way in which I figured this could be solved would be to use some kind of criteria that checks if a track tile is reserved, and in what direction an approaching train will enter / exit that tile.

If this was possible, a signal at the other end of the track could check a tile before the signal at the other end of the track to see if it has been reserved, and if that reservation will cause the train that reserved it to enter that same track, then the signal will not allow entry.


In the meantime, I have the signal check the states of signals at the other end of the track, so that it can give priority to an oncoming train and prefer the other track.

[JGR]

You'll need to post a screenshot or savegame to give us a better idea of what you're suggesting.

If you're refering to a block system, where one bidirectional span of track takes a single train in either direction, then you can simply make the entire track span one signal block, so that only one train can possibly be in at once.

If you're refering to multitrack bidirectional lines with signals (overtaking/switching layouts), then we'll definitely need a savegame.

As for your suggestion, testing whether a track piece is reserved is technically feasible, but is likely to be somewhat clumsy in terms of the GUI, (signal status is already complex enough...)
Testing which way the track piece was reserved from, is not possible simply, as that detail is not saved, and working it out would be too computationally expensive to justify it (search surrounding track tiles until train found).

Hope this helps.

JGR

[steelixb]

I'll post some screenshots in a few minutes as examples.

I figured that since PBS signals don't show red until a train has completely passed through them, this can also be used in combination with checking tile reservations so a signal can conclude on the direction of the train.

I think if this can be acheived, then working bi-directional tracks may be a possibility (if not a little time consuming to set up)

[steelixb]

(See screenshot comments)

(more in next post)