Main Bus Design — The Classic Factorio Base Layout

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

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 smelting throughput. Use our Smelting Ratios Guide to calculate exactly how many furnaces you need to keep your bus lanes saturated.

Mistake 3: 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.

If you’re just starting out, Your First Factory walks through the complete beginner bus setup step by step. Once you’ve outgrown the basic 4-lane design:

Is Main Bus Right for You?

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.