Controlling Two or More Trains on the Same Line?

The planned layout has long sections allowing multiple trains per line. Which presents an interesting set of problems:

• How to create block control in T-gauge?
• How to individually control each train on the same line?
• How to supply power to each train?
• How to vary the power supply to each train for speed control and reversing?

T-gauge is just too small for DCC to be feasible. So...

A schematic of the proposed solution is pictured below.



Schematic of train control concept.

The concept solution is as follows:

• Divide the line into blocks, with overlaps.
• Electrically separate the rails of adjacent blocks.
• Fit train detection to each block and overlap.
• Use software and PC to monitor occupany of blocks.
• Assign in software a unique ID to each train.
• Use software to 'follow' a train as at occupies and clears each block.
• Provide one speed controller per train.
• Use pulse-width modulation (PWM) with H-bridge to generate a variable voltage in proportion to each speed controller.
• Use software and hardware to switch using relays the PWM power from block to block, tracking the movement of the relevant train.
• Isolate power to a block by switching off the relevant PWM power if the occupying train is detected at the overlap and the next block is occupied by another train.

The schematic above shows only two speed controllers per line, i.e. two independently controlled trains per line, but more can be added. The complexity of doing so involves adding additional relays per block section to switch the additional power supplies connected to each block.

Finally, for the concept to work, train detection must be able to detect all vehicles of a train are clear of a previous overlap. Thus 'presence' detection is insufficient; a continuous train detection system is required. How to achieve this in T-gauge will be the subject of a future post - but it can be done!

Layout Plan

Cutting to the chase, here's my proposed layout.

 

Track plan using (mainly) off-the-shelf set-track components on a 1220mm by 607mm baseboard.

And here's how and why I developed it...

All railways are built with a purpose in mind and models are no different. And trains travel from A to B, so it's helpful to have at least an A to justify the existance of trains.

I'm mainly interested in construction and less so the operation of trains - but I would like to see long trains sweeping through expansive landscapes. Due to the super tinyness of the trains, T-gauge does not offer much scope for marshalling so any sidings will only be used for fixed formations. Lastly, off-the-shelf T-gauge rolling stock options have more than a small bias towards modern UK trains, which of course tend to be fixed formation.

Putting this together, my planned layout will consist of:

• A UK setting.
• A two-track main line railway, as is common in the UK.
• A main line that loops to maximise the visual effect of trains moving through the scenery.
• At least one station with two platforms long enought for the T-gauge HST.
• One or more stations with platforms long enough for a typical regional passenger EMU or DMU service.
• A freight container terminal to justify running a locomotive or two pulling a long rake of wagons.
• A headshunt within the freight terminal to enable the shunting of freight trains clear of the main line.

Now for determining constraints. These are essentially the size of the board, how much of that board I want (can afford?) to fill with track and what type of track to use, the latter having been answered in my last post.

A quick read of some websites on baseboard building, selecting a plywood top, and after trip to the local DIY store I have chosen a base size of 1220mm by 607mm to save effort on cutting whilst having a layout that is relatively easy to lug about. Such a board size will leave plenty of room for the largest radii set-track curves.

As for layout planning, there is software for T-gauge such as AnyRail but I've used Microstation CAD software and created standard cells using the T-gauge track specifications. Or you could cut yorself some paper templates and plan it on the floor of your front room.