My Time At Portia

The South Block development project is the fourth set of main missions that you're tasked with completing after having finished the quests relating to Amber Island, WOW Industries, and the Eufaula Desert. A few days after wrapping up the latter's final mission, The Driller, you'll receive a letter from Albert to start you on your way.

The four main missions contributing to the All Roads Lead to Portia achievement are...
Vehicle Pitstop is given by the aforementioned letter from Albert
South Block Development consists of 5 tasks from the Commission Board
The Desert Wind is given by Mint when you exit your home
Long-Haul Bus involves two commissions posted on the Commission Board

If you'd like to plan ahead, especially when attempting to complete all commissions before Higgins steals them, I've listed all the needed materials below so you can efficiently go from one mission to the next without having to wait around long for the materials to be produced.

Vehicle Pitstop
1) Water Tower
- 6 Hard Aluminum (Electric Furnace)
- 4 Aluminum Plate (Industrial Cutter)
- 5 Large Pipe (Level 3 Worktable)
- 5 Copper Plate (Industrial Cutter)
⁠
2) Charge Station
- 1 Industrial Furnace
- 1 Advanced Engine (Research Center or Desert Abandoned Ruins)
- 5 Hard Aluminum (Electric Furnace)
- 2 Large Pipe (Level 3 Worktable)
- 4 Steel Plate (Industrial Cutter)

South Block Development
1) Chimney Roof
- 3 Hardened Clay (Blender)
- 1 Large Iron Bucket (Level 2 Worktable)
- 2 Large Pipe (Level 3 Worktable)
- 2 Aluminum Plate (Industrial Cutter)

2) Iron Wood Support x2
- 10 Iron Wooden Plank (Industrial Cutter)
- 4 Steel Frame (Level 3 Worktable)
- 4 Wooden Pillar (Level 3 Worktable)

3) ⁠Bus Station
- 4 Steel Shell (Level 3 Worktable)
- 6 Bronze Pipe (Grinder)
- 3 Iron Wooden Plank (Industrial Cutter)
- 4 Waterproof Lamp (Level 3 Worktable)

4) Composite Wooden Board x10
- 10 Composite Wooden Board (Industrial Cutter)

5) Composite Wooden Board x10
- 10 Composite Wooden Board (Industrial Cutter)

The Desert Wind
1) ⁠Wind Turbine x3
- 15 Iron Wooden Plank (Industrial Cutter)
- 15 Steel Shell (Level 3 Worktable)
- 15 Bearing (Grinder)
- 9 Windwheel (Level 3 Worktable)

Long-Haul Bus
1) Long-Haul Bus
- 4 Rubber Tire (Level 2 Worktable)
- 6 Single Seat (Level 2 Worktable)
- 4 Steel Shell (Level 3 Worktable)
- 2 Advanced Engine (Research Center or Desert Abandoned Ruins)
- 2 Waterproof Lamp (Level 3 Worktable)

2) Long-Haul Bus
- 4 Rubber Tire (Level 2 Worktable)
- 6 Single Seat (Level 2 Worktable)
- 4 Steel Shell (Level 3 Worktable)
- 2 Advanced Engine (Research Center or Desert Abandoned Ruins)
- 2 Waterproof Lamp (Level 3 Worktable)


Note: If any of this information has changed due to patches or other circumstances, please let me know in the comments so I can update the solution. Thanks!