1 55 14 888 2 56 15 887 3 12 14 15 887 888 119 58 12 13 14 15 887 888 119 4 14 15 87 88 119 5 12 14 15 119 6 115 12 13 14 15 119 12 13 38 10 35 36 37 38 64 65 52 64 65 66 67 68

A tile with two small stations can be upgraded to any green tile with one station and the same exits.
A tile with one small station can be upgraded to any green tile with one station.
A tile with one large station can be upgraded to any green tile with one large station.
Below here there is no neat summary rule.
Bristol