Edit: 10/01. Sorry for the links broken, I re-uploaded with some new bridges (and if i remember correctly, easier ones).
To be able to get this achievement you need first complete the Car/Truck bridges for Tiltin North, to get the extra budget needed for these constructions.Level 1 Level 2 More detailed view:
Level 3 Level 4 Level 5 (bridge will collapse, if it fail, restart the level until you do it)
Level 6 Level 7 (bridge will collapse, if it fail, restart the level until you do it)
Level 8 And that's all for this achievement.
Thanks for the patience.