Here is the full list of all 28 Runaway Train achievements.
10 cities connected in normal mode in one game
15 cities connected in normal mode in one game
20 cities connected in normal mode in one game
25 cities connected in normal mode in one game
30 cities connected in normal mode in one game
50 cities connected in normal mode in one game
Connect 500 cities within multiple games
Connect 2000 cities within multiple games
Connect 5000 cities within multiple games
10 cities connected in night mode
15 cities connected in night mode
20 cities connected in night mode
25 cities connected in night mode
30 cities connected in night mode
50 cities connected in night mode
Connect 500 cities within multiple games in night mode
Connect 2000 cities within multiple games in night mode
Connect 5000 cities within multiple games in night mode
10 cities connected in hard core mode
15 cities connected in hard core mode
20 cities connected in hard core mode
25 cities connected in hard core mode
30 cities connected in hard core mode
50 cities connected in hard core mode
Connect 500 cities within multiple games in hard core mode
Connect 2000 cities within multiple games in hard core mode
Connect 5000 cities within multiple games in hard core mode
1st city connected