Problem with PBS

Grigory1 · Post by **Grigory1** » 20 Jun 2006 22:34

At my scheme of station with application PBS sometimes there is such situation when two trains at through station from the opposite parties call in on the same way and all movement stops
What decisions of this problem are?

Post by **peter1138** » 21 Jun 2006 00:38

Welcome to one of the reasons why PBS was removed.

sc79 · Post by **sc79** » 21 Jun 2006 02:08

Welcome to one of the reasons why PBS was removed.

Not like it works with normal signals either...
Its just more obivious with PBS because the entrances allow a much higher volume of trains through.

bobingabout · Post by **bobingabout** » 21 Jun 2006 07:55

actually, with regular signals, 1 of the trains would actually go into the station platform... there are many solutions to this, many are not possable without pre-signal PBS combinations, however, the easiest solution is to make it 1 large PBS block, instead of 3 smaller ones, you are not thinking PBS yet. remove all the signals from the station platforms, and simply have the 4 end ones at the junction entrances and exits. unfortunatly, this causes problems too...

sc79 · Post by **sc79** » 21 Jun 2006 09:37

I dont think making it all one PBS block really works. Trains reserve the exit as soon as they enter the block, so with 2 exits, you'll only get 2 trains using the station at a time, correct?

That setup (with 4 platforms) using presignals actually works fairly well, and it wont jam like the PBS one does, but when two trains meet head on, one will get forced to turn around, which can be a real pain (especially since I usually only allow them to turn around at EOL).

gkirilov · Post by **gkirilov** » 21 Jun 2006 11:52

Grigory1 wrote:At my scheme of station with application PBS sometimes there is such situation when two trains at through station from the opposite parties call in on the same way and all movement stops
What decisions of this problem are?

Can you please name the track grf and the elrail grf (with links if possible).

Grigory1 · Post by **Grigory1** » 21 Jun 2006 13:24

elrail- is included in OpenTTD
track- xUSSRset http://ttdrussia.net/xussr/grf/xUSSRsow.rar

gkirilov · Post by **gkirilov** » 21 Jun 2006 18:52

By elrails i meant the overhead wires and the pilons. Anyway, they are in the same grf that you pointed.

Wolf01 · Post by **Wolf01** » 21 Jun 2006 19:20

peter1138 wrote:Welcome to one of the reasons why PBS was removed.

remove combo presignals either, they may loop and block your entire network

XeryusTC · Post by **XeryusTC** » 21 Jun 2006 19:21

Wolf01 wrote:
peter1138 wrote:Welcome to one of the reasons why PBS was removed.
remove combo presignals either, they may loop and block your entire network

That is just because the user can't use them, PBS was buggy by itself.

Majestical · Post by **Majestical** » 21 Jun 2006 19:56

I once had a problem quite similar what I did was this:

There are 4 platforms, the 2 center ones I made accesible for trains going both ways. The outer ones were made to allow traffic in one direction only (Both outer platforms in opposite ways ofcourse. I only used presignals and never had a jam once despite heavy traffic.

sc79 · Post by **sc79** » 22 Jun 2006 03:21

That is just because the user can't use them, PBS was buggy by itself.

Care to post a design for a station with 2-sided platforms which doesnt have issues sooner or later? Because I cant find one that wont eventually have trains meet head on and send one off in the wrong direction.

Its not a PBS(-specific) issue, its caused by the type of station layout and the pathfinder not being able to look more than one signal ahead. PBS just caused the more obivious issue because the larger number of trains made it occur more often, and it locked the junction (which was a PBS bug, but not really related to why the station doesnt work).

There are 4 platforms, the 2 center ones I made accesible for trains going both ways. The outer ones were made to allow traffic in one direction only (Both outer platforms in opposite ways ofcourse. I only used presignals and never had a jam once despite heavy traffic.

Presignals wont jam, but trains will get sent in the wrong direction when they meet. With 'trains reversing at EOL only' and heavy traffic, trains suddenly venturing off in the opposite direction can be a major problem.

bobingabout · Post by **bobingabout** » 22 Jun 2006 07:44

sc79 wrote:Presignals wont jam, but trains will get sent in the wrong direction when they meet. With 'trains reversing at EOL only' and heavy traffic, trains suddenly venturing off in the opposite direction can be a major problem.

thats why you need a loopback.

Majestical · Post by **Majestical** » 22 Jun 2006 09:08

bobingabout wrote:thats why you need a loopback.

That sounds nifty, what exactly do you mean with a loopback?

sc79 · Post by **sc79** » 22 Jun 2006 09:21

That sounds nifty, what exactly do you mean with a loopback?

Because the station doesnt work, you need to add a way for the trains that get sent the wrong way to turn around (and then bypass the station). Something like the screenshot, which is hardly a practical solution.

Brianetta · Post by **Brianetta** » 22 Jun 2006 12:34

sc79 wrote:Its not a PBS(-specific) issue, its caused by the type of station layout and the pathfinder not being able to look more than one signal ahead. PBS just caused the more obivious issue because the larger number of trains made it occur more often, and it locked the junction (which was a PBS bug, but not really related to why the station doesnt work).

Not quite. PBS introduced an additional problem to a station design that already had problems. Because every PBS block acts like a presignal block, platforms could often not be entered by a train, because no clear exit could be found (and each platform is a PBS block, in the case of the screenshot at the top). It's not just that trains would meet head to head, and one would have to turn back. It's that trains wouldn't even get that close to each other!

Jim Starluck · Post by **Jim Starluck** » 23 Jun 2006 06:55

bobingabout wrote:...however, the easiest solution is to make it 1 large PBS block, instead of 3 smaller ones, you are not thinking PBS yet. remove all the signals from the station platforms, and simply have the 4 end ones at the junction entrances and exits.

I tried that once. The second train to enter the station went for the same platform as the first one and rammed it from behind.

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