The Crust Main Bus Design — Build a Belt Trunk That Scales

A main bus is one idea: refined oxides merge onto a few long, parallel trunk belts that run the length of your underground base, and everything downstream — smelters, factories, storage — taps off that trunk instead of machines trading belts with each other. The Crust's two-layer map makes this unusually clean, because the busiest lanes live underground where there's no terrain to fight.

The trunk pattern players converge on

A working bus documented by a Chinese player on 贴吧 (Tieba) runs like this:

1. Ore comes down from the dock through the conveyor elevator — the elevator is the chokepoint (4 belts, up to 4 × 600/min), so the bus starts there, not at the machines.
2. Refined oxides hit the main bus first. In this layout the trunk is red belt (T5, 600/min) — "red belts can satisfy it," and one 600/min lane backs three multi-regolith refineries' worth of output.
3. Split per resource into per-ore storage: aluminum ore, titanium ore, rare earth, iron ore, silicon ore, ice, slag and helium-3 each get their own branch and their own storage yard. One resource, one lane, one place drones can find it.
4. Raw stock waits on the trunk's far side. Input belts hold unprocessed material at the left edge of the underground; when a factory needs feeding, its branch pulls rightward from the waiting lanes.
5. Up top, byproducts leave by elevator — slag, fuel and bricks ride a lift back to the surface, where four red belts feed the Expedition Control Center's four input ports (spread the feed across all four: lunar trucks can't be told which center to load).

Feeding smelter rows off the bus

The endgame "Laser Mission" guide on Steam describes the matching factory-side pattern:

• Smelters of one type sit side by side in a row — plan space for it.
• The input belt runs along the north side and extends rightward as you add smelters; the south side carries finished ore backward on a return lane.
• Leave room on the right to extend forever, and room on the left for about six feed belts with a gap before production starts.
• The author ran 15 smelters per resource in a row by the final mission — the bus is what makes that scale possible.

Rules that keep a bus alive

• Underground belts for crossing, surface belts for feeding. Underground segments are point-to-point — perfect for lane crossings, useless for distribution drops.
• Machines don't trade with machines. Everything meets at the bus; factory-to-factory belts are how spaghetti starts.
• Buffer at the branches. Large bulk storage at each branch absorbs rate mismatches — 5,000 items of buffer is about ten large storage containers, per the Laser Mission guide's math.
• Watch the elevator. Everything crossing layers rides it; if the bus starves, check the lift before blaming the mines.

For the machine that starts the whole chain — and the roundabout pattern that feeds it — see the multi-regolith refinery guide; for splitter priority settings on the trunk, the programmable splitter guide covers the three-chevron tool.