The description of the achievement:
"Driver Exceptionnel:
Complete deliveries on all oversize routes in current map (need Special Transport DLC)"

Here are lists that you should deliver them one-bye-one, depend on your DLCs:
#1: https://truck-simulator.fandom.com/wiki/Special_Transport
#2: The list of depart cityes in your in-game email which subject is "New Special Transports".

For Listing #1, every route should be delivered except for the mislabeling of the departure city "Sosnovi Bor" vs. "St. Petersburg". This means that real work comes from "St. Petersburg - St. Petersburg". I don’t know if it’s a game bug or a forum bug. However, it is easily conquered.

Here are some suggestions during your work:
1. No matter what cargo is delivered, you only need to consider the route.
2. Use the quick job should be easier, since you don't need to reverse.
3. If you can't find any of the route, just sleep (have limitation) or take any ferry (suggest Helsinki - Travemünde) and go back to job market.

Hope this guide helps you. Feel free to like, gift or comment if you like, have any suggestions or questions!