Hi! My first post here...

A little background: as a kid (40+ years ago) I had a Märklin layout, and it has always been my dream to be able to run multiple trains, with automatic signals to prevent crashes. back then there was no Digital track control, so it was 2 trains at most, after installing the hideously expensive catenary wires. Well outside my budget at the time! Fast forward to today... I picked up a Digital starter set with a bunch of second hand track and signals.

To automate my track, I looked at the Märklin signal module. Rather pricey and limited in functionality. So I went down the rabbit hole to improve this. What I was after:
- Automatic braking similar to the signal module
- Supporting bi-directional track blocks, including more complex blocks with switches ("points" for the Brits)
- Not using a central controller like CS3 or a PC (making it easier to support ad-hoc layouts... I do not have a permanent one. Yet)
- Supporting the newer Märklin digital signals, which no longer have physical wires to change the signal.

Ultimately I came up with a solution based on Arduinos, supporting various types of blocks (straight runs, branches, sidings, crossings, crossovers between 2 parallel tracks, etc). Each Arduino supports blocks with up to 4 entrances / exits, setting up to 6 signals, and braking when a train approaches a red entry signal of an adjacent block, setting signals according to the position of up to 2 switches in the block, and occupancy of each block. Train detection is done by disconnecting the left and right rail on C-track and checking whether a train is bridging these rails.

So... it works. And I had a lot of fun putting all of this together. But I'm wondering if there are similar (and probably better) solutions out there, for those who do not want to go with a central controller like CS3 or a PC, but want automatic braking and signalling, so they can manually run one train and have a bunch of others doing the rounds automatically. I'm pretty new to digital layout control, and I'd love to hear what products are available, whether commercial or homebrew.

The Märklin digital track runs on AC, encoding the digital signal by flipping the voltage either 1 or 2 times during a certain time frame. If the track power is rectified to negative DC, trains interpret this as a Stop command and will gradually brake to a stop. You can't command them any more but the lights stay on. Even better: restoring normal power to the track will make the train accelerate again by itself. So it's pretty easy to subdivide the layout in blocks where each train can be made to brake and stop by automatic signals.