Here is the full list of all 39 Transport Services achievements.
15 towns, mode easy
25 towns, mode easy
35 towns, mode easy
15 towns, mode normal
25 towns, mode normal
35 towns, mode normal
15 towns, mode hard
25 towns, mode hard
35 towns, mode hard
5 cities, mode easy
15 cities, mode easy
25 cities, mode easy
5 cities, mode normal
15 cities, mode normal
25 cities, mode normal
5 cities, mode hard
15 cities, mode hard
25 cities, mode hard
1st Skyscaper, mode easy
1st Skyscaper, mode normal
1st Skyscaper, mode hard
1st Grand Station, mode easy
1st Grand Station, mode normal
1st Grand Station, mode hard
over 1 million passengers, mode easy
over 1 million passengers, mode normal
over 1 million passengers, mode hard
over 100 airplanes, mode normal
over 100 airplanes, mode hard
over 100 buses, mode easy
over 100 buses, mode normal
over 100 buses, mode hard
over 100 trains, mode easy
over 100 trains, mode normal
over 100 trains, mode hard
1st air link, mode easy
1st air link, mode normal
1st air link, mode hard