How to Solve Train Tracks Puzzles: A Step-by-Step Guide
Updated October 3, 2026 · 6 min read
Every Train Tracks puzzle can be solved by logic alone. This is the order I work in on every board, from Easy 5×5 grids to Hard 9×9, and it's the same order each time: the cheap deductions first, then the line itself.
What you're looking at
A Train Tracks board is a square grid with numbers along the top and left edge, and two dark tabs on its border: the entrance and the exit. Your job is to lay a single railway from one tab to the other.
Each number is the count of squares that hold track in that row or column. Add up all the row numbers and you get the total length of the railway; add up the column numbers and you get the same total. That's a handy check later.
Step 1: Cross out every zero
A 0 clue means that whole row or column is empty. Mark every square in it with an ✕. This is the easiest deduction on the board and it often rules out whole stretches of grid, which shrinks everything that follows.
Step 2: Fill the full lines
If a clue equals the width of the grid, say a 5 in a 5×5 puzzle, every square in that line holds track. You don't yet know which piece goes where, but you know the squares are used, so you can stop worrying about them being empty.
The same idea works partway: if a clue is 4 and exactly 4 squares in that line aren't crossed out, all four are track.
Step 3: Apply the border rule
A piece can't point off the edge of the grid. So a square in the top row can't be a vertical straight, because that would need a connection going up and out. In the top row only horizontal straights and corners that turn down are possible; the same logic applies to every edge.
The only exceptions are the entrance and exit squares, which connect to the border on purpose. Border squares are where this rule bites hardest, so check them early.
- Top row: horizontal straight, or a corner that turns down.
- Bottom row: horizontal straight, or a corner that turns up.
- Left column: vertical straight, or a corner that turns right.
- Right column: vertical straight, or a corner that turns left.
Step 4: Grow the line from the tabs and the grey squares
Squares shaded grey already contain a piece, and the entrance and exit squares must connect to their tabs. Start there. A piece with an open end forces the next square: whatever sits on the other side of that end has to connect back.
Follow each forced connection as far as it goes. When a forced square lands in a row or column that is now complete, cross out the rest of that line and repeat.
Step 5: Count what's left
After each placement, go back to the clues. Compare each number with the squares already holding track plus the squares still open. If the open squares are exactly what the clue still needs, they're all track; if the clue is already met, everything else in that line is empty.
This count-and-cross loop is the engine of the whole puzzle. Most boards fall apart in two or three passes of it.
Step 6: Check the line is one piece
A finished board has one unbroken railway: no branches, no loops, no loose ends, and every number matched. If you've placed a piece with an end that connects to nothing, something earlier is wrong.
When you're stuck, look for a square that has only one possible neighbour left. Track squares need two connections (or one, plus a tab), so a square with a single option can't hold track.