Late-game (anti-behemoth) defense for outposts + rail lines?

[Laogeodritt]

Hi all!

I'm playing a multiplayer rail world and starting to expand out very far into 100M+ ore patches. These outposts are close to a lot of big enemy bases, and we've noticed our standard defensive pods (below, with walls in between for defense—we also use this to turret creep) aren't holding up well against waves with behemoths anymore—they're holding up but taking a lot more damage than we'd like. It's also not economically feasible for us to defend an entire 1000m+ train line with these to stop behemoths munching on our trains!

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This is the first time I've gotten to the point of having behemoths to deal with. We haven't been very careful about managing evolution on this server. I've looked around on /r/factorio and the forums but haven't found too much late-game defense discussions—dunno if I'm using the wrong search terms or just overestimating how strong behemoths are!

What kind of techniques do you guys use to deal with attacks at remote outposts and for your rails? Since they're remote, the ideal solution should be cheap and minimal (just "good enough"), so we can carry defensives as part of our build train; I've seen some gigantic multilayered fortifications on here, but regardless of whether they're overkill, having fortifications that literally double the surface area of an outpost isn't really viable! Nor is defending a rail line like that.

Is the "artificial tree" method (walls placed in a checkerboard pattern) still effective against behemoths? Belts going outwards? Any suggestions for stopping behemoths from stopping travelling trains?

[weltvagbund]

Add some Flamethrower turrets. All you need is Underground Pipes and the Turrets. If you hook them up to Crude Oil, you have a Pipeline to the refinery at the same time. And Fire Damage really helps, Biters are really vulnerable against it, it sticks to the Ground and Damages all the Biters at one spot. Plus it has a 45 Damage base, vs the 20 Dmg Base of a Laser Turret. The other thing you can do is spend more research on the +Damage technologies, so that the Turrets get more Punch.

[mrvn]

I also found it useful to build a maze with stones and later fill in the gaps with belts. If the laser turrets are reachable then the aliens will try to reach them and travel the maze and get shot at. On the other hand with a closed wall like you have they attack the wall instead. And yes, with spitters the maze needs to be some way from the turret to be effective.

[Jap2.0]

What I've done is have a wall two layers thick with three layers of laser turrets behind it (substation- powered), which seems to do well against all but the largest waves. It is also somewhat far out from my main base, so there is much less pollution (and therefore a lot fewer biters) and no9 need to protect train lines, because they are inside the wall.

[Hannu]

I enclose whole area with 2 or 3 walls, line of turrets and fully automated repair system. It is the most economic way to defense both resource wise and play time if you are going to play long time (launch hundreds of rockets). Unfortunately current combat rules does not make any more sophisticated defense practical.

It takes couple of days playtime to clear and enclose about 10 square kilometers. Probably less with current nuclear weapons which seems to be very fast way to clear huge bases and swarms of behemoth enemies.

[mrvn]

I enclose whole area with 2 or 3 walls, line of turrets and fully automated repair system. It is the most economic way to defense both resource wise and play time if you are going to play long time (launch hundreds of rockets). Unfortunately current combat rules does not make any more sophisticated defense practical.

It takes couple of days playtime to clear and enclose about 10 square kilometers. Probably less with current nuclear weapons which seems to be very fast way to clear huge bases and swarms of behemoth enemies.

You should leave gaps in the wall so aliens don't attack the all but try to pass the gap. Gives the turrets more time to kill them before something gets damaged.

[BlakeMW]

Unfortunately the most viable way to defend a rail network is to enclose the entire network in a single great wall and eliminate all spawners from within. A great wall gets relatively cheaper as the area enclosed increases and it'll be cheaper than trying to directly defend the rail lines. Of course further cost savings can be had by exploiting water features. It's what I do in Deathworlds:


A secondary technique if you absolutely must make a long excursion through biter territory is to use really long trains. Trains about 10 long can clobber behemoth biters without losing speed, as such they can keep clobbering behemoths until running out of HP. A behemoth strike takes off about 70hp so the train can run down about 14 before the locomotive explodes (this will set the train to manual - the biters will eat some of it and then lose interest). If you have repairs at both ends it's pretty unlikely the train will hit enough behemoths in a single run to die.

[Laogeodritt]

Thanks, all! Good few sets of ideas I'll have to play around with.

Add some Flamethrower turrets. All you need is Underground Pipes and the Turrets. If you hook them up to Crude Oil, you have a Pipeline to the refinery at the same time. And Fire Damage really helps, Biters are really vulnerable against it, it sticks to the Ground and Damages all the Biters at one spot. Plus it has a 45 Damage base, vs the 20 Dmg Base of a Laser Turret. The other thing you can do is spend more research on the +Damage technologies, so that the Turrets get more Punch.

That might be more viable for our main base area (still rail-cell-based, but it's a cleared area with a defended perimeter), but for remote outposts it does imply getting fuel out there occasionally, and distributing it to the turrets. I guess we can include it with repair packs on a small maintenance train. I'll have to play around with them, I haven't used flamethrower turrets much, mostly because I'm lazy and don't want to have to set up supply provisioning. :V (We've managed to avoid needing automatic repairs so far, until Behemoths started attacking our less well-cleared-out perimeters.)

It's not really viable for long rail lines, since those have a really poor surface area to perimeter ratio.

I also found it useful to build a maze with stones and later fill in the gaps with belts. If the laser turrets are reachable then the aliens will try to reach them and travel the maze and get shot at. On the other hand with a closed wall like you have they attack the wall instead. And yes, with spitters the maze needs to be some way from the turret to be effective.

This sounds like a decent, cheap way of walling and reducing maintenance/repair pack requirements. I've recently been playing with use artifical trees as a blocker (rather than delay), but the behemoths and maybe big biters are too big and their pathfinding doesn't see them as passable, so they attack the wall anyway.

Unfortunately the most viable way to defend a rail network is to enclose the entire network in a single great wall and eliminate all spawners from within. A great wall gets relatively cheaper as the area enclosed increases and it'll be cheaper than trying to directly defend the rail lines.

Yeah, this is what we have for the main base area, since all our rail cells are relatively close by - we cleared out everything in the area of our cluster of rail cells. In this case, we're starting to migrate a lot further out because 10M ore patches are consistently running out, and we'd like to catch a 100M+—so we're probably going to have a long rail line going out big deposits. To make it worth our while, we might try and get some basic materials processing plants down there too, e.g., smelteries, and defend those in a cluster.

A secondary technique if you absolutely must make a long excursion through biter territory is to use really long trains. Trains about 10 long can clobber behemoth biters without losing speed, as such they can keep clobbering behemoths until running out of HP. A behemoth strike takes off about 70hp so the train can run down about 14 before the locomotive explodes (this will set the train to manual - the biters will eat some of it and then lose interest). If you have repairs at both ends it's pretty unlikely the train will hit enough behemoths in a single run to die.

As in, once they're up to full speed, hitting a behemoth is negligible thanks to their inertia? That's good to know—for these really long rails, we were thinking of using a 16-long train as standard, so that would work out perfectly.