Transport Tycoon Forums

Hi guys,

Please take a look at the the attached image, I can't solve this, how does that marked signal is green, i can't figure it out.

Can someone please help?

Posting a link to a savegame would be useful.

The marked signal is green because the exit from the junction block at the top track is green. Presignals don't take whether it's desirable, or actually possible, for the train to reach an exit into account.

The solution, as always, is to stop using block and presignals and just use path signals.

Thank you for your help. Here it goes.

PikkaBird wrote: ↑10 Sep 2022 15:26 The marked signal is green because the exit from the junction block at the top track is green. Presignals don't take whether it's desirable, or actually possible, for the train to reach an exit into account.

The solution, as always, is to stop using block and presignals and just use path signals.

That's a really turn off!

Phack wrote: ↑10 Sep 2022 15:35 That's a really turn off!

why do you think that? path signals are better in every aspect any sane person would ever think of.

Eddi wrote: ↑11 Sep 2022 20:10 why do you think that? path signals are better in every aspect any sane person would ever think of.

Now that's a huge overstatement. Can you make a plain priority merger using only path signals? Not to mention more complex setups such as high speed overflows or self-regulating networks.

the keyword here is "sane".

Generally theres a place for both types of signals, but the differance is that path signals are easier to use especially for people who havnt a clue how to use signals.
The block signals certainly have uses in specific circumstances, but you need to be a player who knows the circumstances that require them.

Eddi wrote: ↑11 Sep 2022 20:10

Phack wrote: ↑10 Sep 2022 15:35 That's a really turn off!

why do you think that? path signals are better in every aspect any sane person would ever think of.

I bet your terminus stations are a nightmare of stuck trains then.

I use a mixture of block and path signals, because there a a lot of situations where path signals can actually cause more problems. Using path signals on terminus stations being the biggest example of how to break networks quickly.

1. Use one-way path signals on RO-RO stations.
2. Use block signals on terminus stations.
3. Profit.

I never use block signals and my terminus stations always work perfectly fine.

As a matter of fact, it is perfectly possible to build a deadlock-proof terminus of any size using only path signals.

odisseus wrote: ↑30 Sep 2022 10:59 As a matter of fact, it is perfectly possible to build a deadlock-proof terminus of any size using only path signals.

could you share an example please?

A two platform example can be found in the wiki. Here's a bigger one.

odisseus wrote: ↑07 Oct 2022 09:43 A two platform example can be found in the wiki. Here's a bigger one.

Wow that's totes amazing, thanks for sharing. I'm new to signals. Say all the platforms are full. What stops another inbound train from passing the pathfinder from behind? Would it stop prior at the inbound one-way, and wait for the outbounds to hurry it along?

Shifty_Girl wrote: ↑18 Jan 2023 10:57

odisseus wrote: ↑07 Oct 2022 09:43 A two platform example can be found in the wiki. Here's a bigger one.

Wow that's totes amazing, thanks for sharing. I'm new to signals. Say all the platforms are full. What stops another inbound train from passing the pathfinder from behind? Would it stop prior at the inbound one-way, and wait for the outbounds to hurry it along?

When the train approaches that station, it arrives on the right-hand track at the bottom-right.
The arriving train will request a path forward, but if all the platforms are full, the pathfinder will fail, and the signal will remain red.

For trains departing the station, their signal will find only one possible path out of the station - the track on our left at the bottom-right. As soon as a train reserves the path to the next signal, no other train can get a path to that same signal.

Also, note the slight difference between the signals at the platforms and the signals at the bottom-right - the ones at the platforms can be passed in the 'wrong' direction, whereas the others can't.

Thanks so much for your reply! I thought as much...I'm a little reluctant to use pathfinders as I've had a couple of crashes with them, so I use everything else BUT those, haha. However, looks like I don't need to overcomplicate everything any longer if I experiment along the lines of your example...though I was proud of my overcomplicated weird setups

I'm surprised that old time players have jumped on the new "path signal" bandwagon. When these new signals work automatically, I don't get a sense of accomplishment for designing the intersection. The programmers might as well put an implicit signal on every other tile and remove their representation on the map if I as the player don't have to make any decisions about what type to build. It's all path path path. Then my trains would sense each other and slow down like Tesla cars on a road, and I just give them the command to go.

When pre-signals first appeared, they were a revolutional game changer and a great fun to understand. Now in the age of smartphones and new Windows, they are out of fashion.

"Put a signal on every tile" is absolutely wrong and will only cause deadlocks in the network.


The main reason I'm all for promoting path signals is that they are the closest representation to how signalling works in most real-life railways.
Second is that they offer yes, a simpler solution to the problems the "pre-signals" were initially made to solve. (I'm writing "pre-signals" in quotes because the in real-life railways a pre-signal is something different.)

And now the block signal types in TTDPatch and OpenTTD are instead used to implement digital logic (computers) for complex logic, and it looks horribly ugly on the map and that kind of abuse of game mechanics grosses me out. I'm very much a proponent for the game getting programmable signals instead of programming the game with signals.

The block signal "programs" have one advantage over the programmable signals: at any given moment, the entire state of the "program" is readily visible to the player. Even though signal logic can be very tricky to implement, at least it is easy to debug.