Solving gridlock on a real life track layout

[TheAmir259]

This was hard to make, but i managed to piece together a real life track layout over in my country. It's rather hard due to the fact that some part of it are hidden under bridges, buildings and that i have to follow an existing layout. Don't ask me the reason why i have to, i have my own plans for this. So here's the map:

KL Sentral Track Layout Problem.sav

(113.65 KiB) Downloaded 36 times

And here's the problem:



There is a switch further down the line;



All the track (Purple, Brown, Pink) are bi-directional, but in practice, track 3 (Purple) is one-way inbound (into central station) whilst track 2 (Brown) is one-way out of the station. Track 4 (Pink) is rarely used, some trains even park there sometimes (even though it's not a proper spot). The problem is whenever a train exits the freight station (Blue), they have to go through track 3 (Purple). As you see in the second picture, the crossover for the trains going to Seremban (Red) are further down the line. This creates a very sweet spot for gridlock. I haven't mastered entry-exit signals nor combo signals, but i found another way to solve the problem. It is however a little complicated so I was wondering if it is really possible to use entry-exit-combo signals to solve this problem.

The rule here is that no tracks should be messed around with, they are there to stay. KLS Bypass (Green) can be turned into a station for turnaround, so is Track 4 (Pink), so my solution is that they zig-zag to get to track 2 (Brown). Another way is to of course, manually control the area, by stopping any necessary trains. In real life, there's not much trains going into the freight station (Blue), thus it's easier to control the situation. Also, this is just a test map, not a proper one. It's to keep the layout for future use. The signals inbetween the triangular junction can be removed, but it's there in real life to provide a smooth flow. So what are the possible ways of solving this problem?

[jfs]

The real-life solution to this kind of problems is to have special interlocks in the signalling system. In old days, those were physical interlocks preventing you from moving a lever to change a signal or switch, when another lever was set in a particular position, or not yet set in a particular position. Later they were constructed into electronic relay-based circuits, preventing the dispatcher from preparing routes when preconditions weren't met. Modern signalling systems of course has this controlled by software.

And this leads to the OpenTTD solution: You need signals with more advanced logic than block signals, block pre-signals, or path signals can offer. I believe there are programmable signals in the JGR patch pack. I think you can use those to set up rules to e.g. prevent one signal from turning green when one or more other signals are red, i.e. that the block they protect is occupied. That way you can ensure a bi-directional track "locks" into a single direction when a train chooses it as a path.

[Eddi]

on a less "you need X-Y-patchpack" level, there are basically 2 ways you can combat gridlocks with the base game, that is

1. make at least one of the bidiractional tracks unidirectional, so trains always have an exit that can never be blocked by an opposing train
2. make extensive use of timetabling to properly alternate incoming and outgoing trains, so the gridlock situation never builds up.