Tracks

Each new track costs more money and building time than the last; the first link to a new city also costs a one-off connection fee.

Tracks connect your network to industries and cities.

Cost

A track has no fixed cost: money and building time grow with the number of tracks you already own. The first ones are cheap and fast; the gap between the 20th and the 80th track is huge.
The game shows the cost and time of the next track before you confirm.
Reaching a city for the first time adds a one-off connection fee: your home city is free, the second city stays affordable early on, then each new city costs much more.
The number of tracks you can lay is set by Track production, which also cuts their building time.

Build outward from your home city, nearest industries first.
Shared tracks used by several goods are better than parallel tracks.
Connect nearby cities first: shorter routes need fewer tracks and pay off sooner.
Before a big expansion, check that your income covers it; if the Bank limit stops you from saving, upgrade the Bank first.
The worker Jay Gould cuts the cost of tracks and connection fees.