Issue description
I think this has been an issue for quite a while now. I did a scan through the bug reports and didn't see anything matching this issue. I'm also a bit unsure about whether this is a bug at all or more of a suggestion, as I am unsure how excavators 'lock' mining jobs to ensure other excavators don't try and complete the same job at the same time, but I think it lines up with what I would consider a bug.
If you have a dig site within a mining area with accessible edges at different elevations and two or more assigned excavators, excavators will sometimes move back and forth between accessible dig points at different elevations instead of just sticking to whatever elevation they are currently at and always working their way from there.
See the following screenshot for an example, specifically the far right of the three dig sites/mining designations:
This designation is one square wide, starting at +5 and going up to +19 to create a 'ramp'. Accessible dig points exist at both +5 and +19.
In this case, I have two small excavators working on this job. Both excavators are currently swapping positions, one is moving down from the +19 side to the +5 side and the other is moving up to the +19 side from the +5 side. This doesn't make sense to me as each excavator can still continue mining from their original point (the excavator mining at +5 can continue from where it is and likewise from the other excavator at +19). It doesn't happen all the time so something specific triggers this but I can't yet isolate what it is.
It's especially annoying as, with the current behavior for trucks assigned to excavators, trucks that are assigned to that specific excavator won't follow the excavator and instead wait for the excavator to arrive at the new location before driving to it. Only once the excavator arrives do the truck(s) then drive to it, so you techincally are waiting double the time, first for the excavator to drive to the new site and then for the trucks to drive to the excavator. If excavators are always moving around, this adds a lot of additional time to a dig job, especially if it is a large designation and/or you have a lot of assigned excavators.
In addition, I can force this issue to occur if I make the ramp designation two squares wide instead of one. See the following screenshot of me doing this to the dig site from the first screenshot.
In this screenshot, I just increased the width of the designation to two grid squares. An excavator has immediately after left the top dig site and is driving down to the bottom, when instead I expected the excavator at the top site to just continue digging from there versus driving down to the bottom and wasting time.
Perhaps, with any mining area, just have excavators always try and mine from the closest accessible point every time they attempt to find a mining "job" within the designation. I assumed this would have already been the case but, with this issue, I guess not.
E.g if an excavator starts mining a square at a +5 designation, finishes it's job, and mining jobs are still accessible at the +5 elevation, always find the nearest one and continue. Only if none are available at the current elevation, then move to another elevation, either picking the next closest elevation value with an accessible point, or doing a random selection.
Reproduction steps
- Create a mining designation with accessible (reachable via pathfinding) mining designations at two unique elevations. 'Width' of the designation doesn't matter but it seems to happen more if the designation is at least two grid squares wide. See both prior screenshots for examples. The two or more accessible points don't have to be part of a continuous designation as in my examples (mining a 'ramp' for example) but I think the issue occurs no matter what.
- Assign two or more excavators of any type to the mining designation along with one or more trucks. Note: I thought I had seen this happen with just one excavator as well but couldn't recreate it via the testing I was doing in the first screenshot above. Will update this if I see this occur.
- Wait for the excavators to start mining. This issue should trigger pretty quickly although it doesn't seem to always happen for some reason.
Game version and build number
v0.8.8
Which branch of the game are you on?
Stable
Operating system
Windows