The Auto-designer: layouts from your own track
Benjamin | TrackDrawer.com · published 31 October 2026
The Auto-designer is the part of TrackDrawer that designs track plans from the track you already own. You give it your stock, your baseboard size and what you want the layout to do; it lays variants that close, fit on your baseboard and never use a piece that is not in your box. If it finds nothing, it tells you why, with numbers.
What you enter
- Stock. You enter your track by part number, or add a whole starter set or extension set in one go. The app knows the dimensions of every piece from the manufacturer's catalogue. The Auto-designer works per track system: a plan in C track uses only C track.
- Table. A rectangle, an L or U shape with an edge margin, or the floor, where the area grows with what you lay. The edge margin is the distance from the edge of the roadbed to the edge of the baseboard; a new plan starts with 50 mm.
- Goals. What the layout should be able to do (see below).
- Options. A minimum radius (useful if you run long coaches), the number of variants, whether crossings and turnouts may be used (mixed, preferably first, or not at all), and "Use as many pieces as possible". With that last option, the variants that use the largest share of your stock come first.
Which shapes it lays
For each radius the Auto-designer tries a series of shapes and keeps only what really closes and fits:
- Oval, the basic form: two semicircles with straight sides between them.
- Oval with passing loop: two turnouts on one side with a second track, so two trains can wait for each other.
- Station: a passing loop on one side and a siding with a buffer stop on the other.
- Station with two platforms: a passing loop on both sides.
- Yard: two sidings side by side from two turnouts in a row, for parking wagons.
- Double track: two parallel loops on two radii (for example R3 and R2), separate or joined by a crossover so a train can change tracks.
- Dogbone: two reversing loops joined by two tracks close together. It looks like double track, but it is one long continuous run. More in the dogbone.
- Polygons: triangle (three corners of 120°), diamond (60° and 120°), hexagon and octagon, each with straight sides between the curves.
- L, U, T, S and cross shapes: loops with inward corners that follow an L or U baseboard or leave a gap so you can reach the track.
- Figure eight with crossing: two loops that cross over a crossing piece.
- Figure eight with bridge: a figure eight without a crossing, where the track climbs in one loop and passes over itself.
- Line with two reversing loops: a single-track line with a reversing loop at each end. On two-rail DC, every reversing loop needs a reversing module.
On top of that, it hangs extra turnouts on the straight sides of a shape when your stock allows. That gives names like "Station on R1, plus 2 sidings" or "Dogbone on R2, plus siding and yard". If you have curved turnouts, such as 24671 and 24672 in C track, it also lays a passing loop in the curve.
What it checks
Every variant is laid piece by piece with the real geometry and shown only when it passes the check:
- the track closes: no closing gap and no open ends, apart from sidings with their buffer stop;
- no two pieces overlap;
- everything lies on the baseboard, including the edge margin;
- the parts list stays within your stock, part number by part number.
For the figure eight with bridge it also checks the gradient and the clearance under the bridge. If you carry on drawing in the editor yourself, the check keeps running: gradients that are too steep, a sharp change in gradient, tracks closer together than the NEM spacing, an S-bend without a straight in between and, on two-rail, the polarity of a reversing loop.
The four goals
| Goal | What the Auto-designer looks for |
|---|---|
| Closed loop, as long as possible | At least one loop a train can keep running on, with as much running length as possible |
| Several trains at once | Double track or passing loops, so trains can pass each other |
| Station and shunting | A passing loop and sidings for stopping and shunting |
| Variety | Double track and sidings rather than a bare oval |
You can tick several goals at once. The goals decide which variants come first; an oval can still appear in the list, but it drops down when you ask for a station.
What it lays from a typical box
To show what that means in practice, TrackDrawer measured the Auto-designer with a typical box of Märklin C track: for each radius R1 to R5, sixteen 30° curves (a full circle plus four), eight pieces of six straight lengths, three left and three right turnouts, four counter curves, four extra compensation pieces, one crossing and three buffer stops. The edge margin was 50 mm.
| Baseboard | Variants (among others) | Pieces | Track length |
|---|---|---|---|
| 100 x 90 cm | Oval R1 | 16 | 2.53 m |
| 100 x 90 cm | Triangle on R1 | 12 | 2.26 m |
| 180 x 90 cm | Oval R1 | 22 | 4.11 m |
| 180 x 90 cm | Oval R1 with passing loop | 25 | 4.64 m |
| 180 x 90 cm | Station on R1, plus 2 sidings | 40 | 6.58 m |
| 180 x 90 cm | Yard on R1, plus siding | 38 | 5.92 m |
| 200 x 120 cm | Double track R3/R2, plus siding and yard | 56 | 10.76 m |
| 200 x 120 cm | Station with two platforms on R2 | 36 | not measured |
| 200 x 120 cm | Dogbone on R2, plus siding and yard | 37 | 6.31 m |
Two things stand out. The "triangle" on 100 x 90 cm consists of twelve R1 curves and nothing else: with no room for straight sides it is simply a circle. And R2 and R3 only come into play from 200 x 120 cm, because a loop on R2 is already 915 mm deep. What exactly fits on the most popular baseboard size is covered in an H0 layout on 180 x 90 cm.
When it finds nothing
An empty list is not the end. The Auto-designer looks for the cause and states it in plain words, in this order:
- Too few curves. A closed loop needs a full circle of curves with one angle: twelve 30° curves, or sixteen of 22.5°. If you have enough degrees but in different angles (30° and 15° mixed), it says so separately.
- Minimum radius too high. A loop would work with your smaller curves, but you excluded that radius.
- Too few straights. It lays at least two between the curves.
- Table too small. It gives the size of the smallest loop next to your baseboard size, for example for C track R1: 82 x 76 cm without edge margin.
- Turnouts. A station needs at least two turnouts. If there are turnouts in your stock but no variant uses them, it tells you which piece is missing: a left and a right turnout, two counter curves, two compensation pieces or a buffer stop. If everything is there, the straight side is too short: in C track a passing loop needs at least 72 cm of straight.
After that it tries a wider question: just a continuous run on the smallest radius. If that fails too, you get an open plan from your stock (a straight line, a line with a curve or a U shape, with buffer stops if you have them) and the smallest oval that would work, with exactly what is still missing, such as "2 more R1 curves needed (24130)".
Frequently asked questions
Why do I keep getting the same shape?
Because your stock or your baseboard leaves little choice. Try another goal, set crossings and turnouts to "preferably first" or tick "Use as many pieces as possible". Free accounts get 5 variants per run, Pro up to 50.
Can I change a variant afterwards?
Yes. A chosen variant is an ordinary plan in the editor. You move, add and remove pieces, and the check and the parts list follow along.
Try it yourself
If you still have a box of old track, read give your old box of track a second life first. Then enter your track and your baseboard size and let the Auto-designer show what is possible with exactly your pieces.
