| A tile with two small stations can be upgraded to any green tile with one station and the same exits. | |||||
|---|---|---|---|---|---|
| 1 | 55 | 14 | 888 | ||
| 2 | 56 | 15 | 887 | ||
| A tile with one small station can be upgraded to any green tile with one station. | |||||
| 4 | 14 | 15 | 887 | 888 | |
| 3 | 12 | 14 | 15 | 887 | 888 |
| A tile with one large station can be upgraded to any green tile with one large station. | |||||
| 5 | 12 | 14 | 15 | ||
| 6 | 12 | 13 | 14 | 15 | |
| Below here there is no neat summary rule. | |||||
| B | 12 | 13 | 38 | ||
| 52 | 64 | 65 | 66 | 67 | 68 |