Those two guides above work if you want to do the "Legit" way. I did both levels in about 20 minutes my way. If you want to do a faster way you can.
1. Put platforms where the passengers respawn
2. Hold Select - Click Start Point
4. Put the little flag parallel to where the platform is. Passengers will jump in
5. Hold Select - Reset - The train will show up
6. Go to the station - Hold Select - Click Start Point
7. Set the flag. Reset. The train will show up and the passengers will jump off.
As confirmed by people in the comments - DLC is not required for this achievement, however, the bedroom passenger missions were required as mentioned by MoneyShot360.
Here's a video showing you how to do it (9:42 in the video) . It's in Portuguese, but you can use the CC or just watch how I do it. Please do not downvote just because you don't understand a second language.