Suggestions on depot's built-in signal

[frankie609]

Hi,

It would be very nice if there would be a choice of what kind of built-in signals that comes with a depot whenever you build one.

Has anyone implemented the "depot trap" setup on openttd as posted here? ->
http://www.tt-forums.net/viewtopic.php?p=633925#p633925

Take a look on the that post before moving on my details why that setup won't work.

Let's call:
signal 1 - the pre-entry signal.
signal 2 - the two-way combo signal in front of the depot
signal 3 - the one-way combo signal just below the signal 2

Here's how it will end up messed up.

The main objective "depot trap" setup is to prevent clogging up the entrance of the station whenever congestion is imminent. To do this the setup provides a depot so that if the platform is full the last train entering the station will enter the depot. On the given URL, he placed signal 2 to prevent the train from exiting the depot until there's available platform. The signal 1 was placed so that the train will be forced to enter the depot if there's no available platform (because signal 2 was almost always green). And because signal 2 was almost always green, if there's no platform available, all trains would enter the depot. If the signal 1 was just an ordinary signal, in case there's no available platform, any train would have entered the station until signal 3 ignoring the depot.

That setup works quite fine but with a small chances of getting clogged up. There's a race condition on that setup and in that condition there's a chance it will mess up the whole concept of "depot trap" concept.

Here's how. If there's a train in the depot, and if, as soon as possible a train left the station, and there's an incoming train, chances are the train leaving the station triggers a green on signal 2. As soon as the signal 2 goes green, a train in the depot starts to pack up and attempts to move out off the depot, the Train A. But the fast incoming train, Train B, triggers signal 1 before even Train A tries to trigger signal 2. So in that scenario Train A is already "outside" the depot BUT just before the position that triggers signal 2. So that made train A wait on the gates of the depot (I know there's no gates just to make things clearer). While Train A waits on the gates of the depot, Train B occupies the platform leaving Train A just waiting outside the depot but just before the signal 2. Unfortunately there are other trains following Train B, and to make things worse, those trains will not be able to enter the depot because Train A is on the gates of the depot and thus clogs up the entrance to the station. Those training following Train B should be inside the depot.

My solution to the problem is to create a depot with a built-in combo signals, not pre-entry signals. If that was the case, Train A would have no chance of waiting on the gates of the depot just before the signal 2 because the only reason Train A keeps waiting on the gates of the depot is because of signal 2. The beauty of having combo signal built in into the depot is that the pre-entry signal now checks the depot to signal a green and the pre-entry signal does not need the depot to have the signal 2, which is problematic.

Please leave your comments. Thanks.

[aahz77]

I don't think there are many TTDPatch players that have the need of changing the type of the built-in signals of depots, because most TTDPatch players build their networks very realistic, thus having no need for "overflow" or "trap" depots. If it could be implemented very easy, a dev could give it try (I would turn that switch on and test the feature for bugs, but I probably wouldn't use it in my games). But as there is still a bug with the depot signals of AI companies, I doubt any TTDP developer will put any energy into this.

As for the OTTD community, I can't comment it.

By the way, wrong forum section. This is Forum Suggestions, not OTTD / TTDP Suggestions.

[CommanderZ]

I don't see use for escape depots these days. Presignals or PBS can solve such sitiations much better.

[frankie609]

I somehow agree on your perspective that depot trap setup is quite inefficient, but it has its own purpose. Plus, it could be used in conjunction of other station setup strategies. It is also useful if there's just not enough space isn't it? But that's besides the point. I just thought it would be nice if there were choices and it adds flexibility to the game. Who knows, it might introduce new concepts besides the "perfect depot trap".

Either way it's one of the great games i've played.