Underground Belt

Lore & Background

In the sprawling industrial sprawl of the player's base, the underground belt is the quiet workhorse that makes the impossible layout possible. Where a yellow belt snakes eastward and a red belt must cross north-south, the underground belt simply steps aside, sinking its cargo beneath the surface for a brief moment so the crossing traffic flows unimpeded above. It asks for no power, makes no noise, and demands no attention—yet without it, the elegant interlocking of multi-layer belt networks would collapse into a tangle of inserters and manual routing.

In Their Own Story

The shift was quiet. No alarm, no explosion—just the soft clatter of iron ingots sliding into a gap where a belt used to be. Mira watched from the catwalk as the yellow line dipped beneath the surface for exactly one tile, her cargo vanishing into the dirt and re-emerging on the far side. Above, the red belt hummed steadily, oblivious. She set down her wrench, leaned against the railing, and smiled. Three weeks of inserter gymnastics, solved with two iron plates and a piece of rubber. The base could finally breathe.

Reader's Guide

Function: The Underground Belt replaces one tile of an existing conveyor, creating a 1-tile gap. A second belt can then be placed in that gap to cross over. The Long Underground Belt does the same but removes two tiles, allowing a 2-tile crossing gap. Items on the lower belt pass through the gap seamlessly at full belt speed; the upper belt is completely independent. Input/Output: Neither variant has discrete input or output slots. They are belt segments, so items flow through them at the speed of the belt they belong to (yellow 15/s, red 30/s, blue 60/s). Power draw: Zero. The underground belt consumes no energy and has no power connection. Technology: Unlocked by the Logistics technology (short version). The Long Underground Belt is unlocked by a subsequent logistics-related research. Placement quirks: You must already have a belt in place; the underground belt is placed *on top of* an existing belt tile, removing it. You cannot place it in empty space. The Long Underground requires two contiguous belt tiles. Once placed, the gap is transparent—another belt, or even a straight belt segment, can occupy it. Pairing: Works identically with yellow, red, and blue belts. Pairs naturally with splitters, combinators, and any belt-routing infrastructure. In large bases, layering multiple underground belts in a grid creates clean multi-level crossings without a single inserter.

Did You Know?

• The underground belt is one of the very few items in Factorio that modifies already-placed infrastructure rather than being a free-standing object—you place it onto an existing belt tile.
• Items visually sink below the belt surface and re-emerge on the other side, a small animation detail that makes crossings feel almost organic.
• Because the underground belt has zero power draw and no moving parts, it is essentially 'free' to operate, making it the cheapest possible belt-crossing solution in the game.
• You can stack multiple underground belts in a grid pattern to create a full 2×2 or larger crossing, allowing both belts to turn or branch at the intersection point.