Achievement lvl 23

Does anyone know how to get this? I can get 3 stars on the level or I can get 10 people on the first train, but every time I go for the achievement there is always one straggler that puts me over the time limit. The last time I played he showed up so late that the last train had left the station. Any help would be greatly appreciated.

Nevermind. I finally got it! I have no idea if I guessed the right formula or just lucked into the right timing, but right now I'm just happy to have gotten the achievement.

It took me several...ok...many, many times to figure out the trick to this level.

Do not collect any gas until 10 people are at the the station. Then only collect 2 cans of gas (for a total of 100 needed to call the train). Finish clearing only boulders that have gas cans behind them & clear any thieves that are left. Collect the gas cans, but do not collect the last one until there are 2 people on the platform.

Hope this helps. If you need more detail, just ask.

Thank you! I knew it was something I was doing that was triggering at least the first train. After getting the achievement once I couldn't reproduce my results so I knew my original theory was wrong.