An interchange for 1+1 trains

[sparr]

For my next factory I'm considering short trains, 1 locomotive and 1 cargo wagon. Don't ask why; it's complicated.

Part of thinking about this plan led me to thinking about interchanges. With such short trains, it's possible to mix chain and block signals, with end-blocks inside the interchange that don't cause deadlocks.

Here's 1/4 of the interchange (just rotate and paste 3 more times to make the whole thing):

a.png (1.06 MiB) Viewed 2882 times

Here it is with four trains, all with green signals ahead and open cross-paths behind:

b.png (1.1 MiB) Viewed 2882 times

There can actually be two more trains in there, at the bottom turning onto the diagonal and in the upper half of the diagonal. The entire interchange can have as many as *24* trains fully inside it at once.

I do not think there are any deadlock conditions for this interchange.

Blueprint string:

Code: Select all

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[2Nooby]

This is a really cool concept, but it would be so much better with 1-2-0 trains as they have the same top speed as the 1-1-0s but double the throughout. In terms of maximum throughput this is a good plan, although as you have found it scales badly with train length.

[steinio]

The train in the second column from south to north is already deadlocked, if the train in the first row from west to east cant't pass...

Why do you use a block signal before chain signal in the first row?
Don't make sense to me.

[sparr]

The train in the second column from south to north is already deadlocked, if the train in the first row from west to east cant't pass...

I don't think you're using the typical meaning of "deadlock". A deadlock is when multiple trains are mutually blocking each other, so none of them can ever move unless one of them backs up.

Here's a two-train block signal deadlock that wouldn't have happened with chain signals:

Screen Shot 2016-05-29 at 10.44.52 AM.png (384.29 KiB) Viewed 2816 times

The trains in my interchange above aren't deadlocked. One of them can eventually leave. (actually, as pictured, at least one of them would already be moving)

Why do you use a block signal before chain signal in the first row?
Don't make sense to me.

The purpose of the block signal ahead of the chain signal is to create a position inside the interchange where a train can stop. If I only used chain signals, then each train would reserve a full path through the interchange. That's great for long trains and small intersections, but terrible for short trains and large intersections.

The purpose of the chain signal after the block signal is to keep the train from blundering forward and causing a deadlock situation.

Would it help if I illustrate it?

[sparr]

This is a really cool concept, but it would be so much better with 1-2-0 trains as they have the same top speed as the 1-1-0s but double the throughout. In terms of maximum throughput this is a good plan, although as you have found it scales badly with train length.

I am really hoping that all the train UI changes we get in 0.13 will come with some train mechanic improvements. Fingers crossed that we get smarter signals, or S-curves, or... something. There are a lot of possibilities that would allow for better interchanges with longer trains. My first real train game is right now, and I'm doing 1-3-1. In hindsight, 3 is a terrible number of train cars. Way too hard to split up loads into thirds, etc. If I don't do 1-1-0 next time, then I'll be doing 1-2-0 or 1-4-1.