[jstummbillig]

Loops vs lines: Loops only in a dense core where you can keep shapes alternating and include a square. Use lines for suburb<->core and river hops.

Lines or carriages: Early add lines, midgame add a loco, then carriages on the trunk that is actually redlining. Late add an interchange at the first overloaded transfer before more cars.

Tear-down: Hm... how much, not sure how to quantify. Definitely something you must do in every long running game but the extend is different. As a heuristic: Pause and rebuild when queues outrun a single weekly upgrade. Reorder shapes, make sure every line touches a square, split any mega-hub into two nearby transfers.

As you probably have guessed: There is no real silver bullet. Knowing the best move is basically impossible, the space is too complex. As a most useful general skill, it's important to recognize problems very early and optimize ruthlessly.

[stingraycharles]

How did you learn strategies? There are very few reliable sources of strategy for both games, compared to other, more common simulation games.

[jstummbillig]

Just by observation/feel, really. I don't think I have looked at any strategy guides. Figuring that out to me is the fun part.