Factorio main bus vs modular factories: organizing your first base

What a main bus actually does

A main bus reserves parallel routes for important materials so that new assembly lines can branch off in a predictable manner. It is a planning convention, not a special building. The main benefit is that you can visually identify where a resource comes from and how it is distributed.

A bus still has throughput limits. More consumers on a line do not increase the quantity entering it. A shortage downstream often begins at mining, smelting or a heavily loaded belt upstream.

When modular districts work better

Separate modules dedicate an area to an intermediate product, science pack or infrastructure type. This can reduce clutter and make failures easier to isolate. Modules may exchange materials by belts, trains or another unlocked logistics system.

Specialization introduces transport planning. If modules are far apart, you must account for the cost and complexity of moving parts. A small early factory does not need a rail network just because large showcase bases use one.

Make the choice from your bottleneck

Use a compact bus for early predictable resources if expansion space is available; use modules when a line becomes tangled or a product needs its own space. Many successful factories blend the two approaches.

Before rebuilding, write down which throughput constraint the change is meant to solve. Layout aesthetics alone do not establish whether the rebuilt factory will produce more.

1. 01Identify two ingredients that repeatedly run short.
2. 02Trace supply and consumption before moving machines.
3. 03Leave a visible expansion corridor in either layout.