The Factorio Benchmark Website

test-000031 : Is it better to have two miners each mine a half lane, or have one miner mine into a splitter for a full belt?

Factorio Version 1.1.91

The TLDR

Mine into splitter instead of using 2 miners. Don't use output priority. See also: test-000032

The Question

It is possible to mine directly into a splitter and then sideload the two ore streams into one full belt. It is not known if that performs better, worse, or the same as just using 2 miners to fill the belt.

The Test

The test consists of otherwise identical designs cloned to a large amount of production (roughly the amount of ore needed for 50k SPM). A few variations of each design are posed to further refine the hypothesis.

Mining productivity was set high enough that a single miner could sustain a full blue belt worth of output, but not excessively higher than that level.

The first of these designs is a simple 2 miner setup

Two miners, but directly into an underground belt

Two miners, with one normal belt before the underground belt

The expectation of adding underground belts is to force the belt insertion transport line lookup closer to the point of insertion. One of these puts underground belts right at the miner, and one adds an additional space before the underground. It was observed that by having the underground right at the miner, the wakeup list debug visualization would flicker as the miner operated.

Basic splitter based setup

Adding undergrounds after the splitter and sideload

Adding undergrounds after the splitter with an additional buffer tile

Adding input priority

Adding output priority

The competing designs and variants are mining straight into a splitter. One variant is to add an underground belt to force the transport line lookup point sooner. This comes with two options, since it looks like the closest possible underground position results in the wakeup list debug visualization flickering. Another variant adds input priority to the near side of the miner, and the final variant adds output priority to the splitter.

Each design was saved in a map and then each of the maps was benchmarked using the inbuilt Factorio benchmark 3 times at 1000 ticks each. Care was taken to put each design in the same starting position before cloning to minimize the chance of performance effects due to chunk positioning.

The Data

• Variants that result in the miner wakeup list visualization flickering should be avoided, since they are strictly worse than their spaced counterparts
• Mining into a splitter is better than using 2 miners to achieve the same thing.
• Output priority on the splitter should be avoided. Input priority is down to measurement tolerance, so shouldn't matter either way.
• Using underground belts showed a benefit for the 2 miners configuration, but a penalty for the splitter based configuration. That would suggest that the item insertion point lookup doesn't exist for sideloaded belts, which does in fact make sense.

All maps will be uploaded here.

Closing

When producing/consuming a full blue belt, use a single miner mining into a splitter to achieve the best performance.

There are additional factors not accounted for which might affect these results. One: what happens at much higher mining productivity levels (ie. far more than necessary to saturate a blue belt). Two: does this performance profile hold true when a belt is not fully utilized? There are possibly more factors not being thought of as well.