How to unlock
Complete a particular objective by delivering 'Short Logs' only
Best way to do it
The best way to accomplish this achievement is surprisingly on the River. You'll need a truck that has the add-on Carriage installed, a Type B-130 will do nicely since you can unlock the achievement OLD STILL GOOD at the same time! After crossing the river you find the paved road that we shall call the ring road or RR from now on. Go to the lumber yard that's closest to the western edge of the map. Load up on short logs and drive the RR to the Objective on the northern side of the river. Do this 4 times without going to the main menu or leaving the game and you should be good.