What Is a Main Bus?
A main bus is a set of parallel belts (the "bus") carrying raw materials through your base. Assembly blocks pull from the bus and push finished products back onto it.
Think of it like a highway: resources flow down the middle, factories are off-ramps.
Recommended Bus Width
| Material | Lanes (Basic Belt) | Lanes (Fast/Express) |
|---|---|---|
| Iron plates | 4-6 | 2-3 |
| Copper plates | 4-6 | 2-3 |
| Steel plates | 2 | 1 |
| Green circuits | 2 | 1 |
| Plastic bars | 1-2 | 1 |
| Coal | 1 | 1 |
| Stone | 1 | 1 |
How to Build It
Step 1: Clear a Large Area
You need at least 200 tiles wide and unlimited depth. The bus grows as you research more technologies.
Step 2: Lay the First 4 Lanes
Start with iron plates (2 lanes), copper plates (2 lanes). Leave 3-tile gaps between lanes.
Step 3: Add Off-Ramp Assemblers
Build assemblers perpendicular to the bus. Use long-handed inserters to reach across gaps.
Step 4: Expand as Needed
Add more lanes (steel, green circuits, plastic) as your factory grows.
Common Mistakes
Mistake 1: Building the bus too narrow. You can't widen a main bus once it's surrounded by assemblers.
Mistake 2: Not planning for train unloading. Trains need to dump into the bus at the start of the line.
Mistake 3: Forgetting power poles. Run big electric poles along one side of the bus.
Is Main Bus Right for You?
| Base Style | Best For | Downside |
|---|---|---|
| Main Bus | Beginners, mid-size bases | Inefficient at megabase scale |
| City Blocks | Megabases, train-based | Complex setup |
| Megabase (beaconed) | UPS-optimized builds | Requires deep game knowledge |
Bottom line: Main bus is the best starting design. You can always transition to city blocks or beaconed modules later.
Next: Base Design Patterns — compare all major design patterns.