Tunnels allow the player to send a conveyor under the ground. They are used with conveyors of all types, but not conduit. Tunnels must be in a straight line on the x or y axis and they can only span a maximum of two tiles. You must build an entrance (input in red ) and an exit (output in blue) tunnel for a conveyor to move items
through them, bringing the total cost of a working tunnel to 4 iron. Tunnels can be placed next to specialty transportation blocks as well. Tunnels have a delay in sending items through but they will send items through at high speeds, with a delay of ~.4 second per block including tunnel blocks. Because of this delay it may sometimes look like tunnels transport slowly or have a storage like other transportation blocks. Tunnels are an integral part of advanced transportation techniques.


The BasicsEdit

Tunnel blocks face the direction they are placed with a flat concrete back and a dark “tunnel” face. Tunnels can span either 2 blocks, 1 block, or zero blocks. For a tunnel to function correctly you must have and input tunnel and an output tunnel facing away from each other. Input and output tunnel blocks need a transportation block (conveyors, etc) connected to the tunnel block face, the transportation block connected to the tunnel block determines if it is an input or output tunnel. Therefore the required area to build a tunnel would be 1x 6 maximum and 1 x 4 minimum.

Conduit Junction:Edit

This is an important way to use tunnels because there is no other way for a conduit and a conveyor to cross paths.

Avoiding Router:Edit

Routers are very useful blocks. Sometimes you may want to limit what conveyors a router can feed to in a tight space, like in the middle of other conveyors. One strategy for this issue is to use tunnels to avoid the router or other similar outputs.

Advanced Tunnels:Edit

These tunnel builds can be invaluable for their special behavior. The principle that these builds function on is that a 0 span tunnel can fit inside of a 2 span tunnel sharing one of the tunnels for a 3 tunnel block build. The knowledge that tunnels could be used in this way was posted by Anuke themself in the Mindustry discord.

Overflow Tunnels:Edit

By using a 3 block tunnel build with two outputs you get a kind of splitter (like a router) but with special priority behavior. Items will flow into the single input tunnel and will feed the first output tunnel block. If this conveyor line becomes full the items will feed the second output tunnel block. With this build you can assure a conveyor line is always full without clogging your item flow. An example would be for use in feeding iron to a smelter when you still want extra iron to “overflow” to your core.

Tunnel Merge:Edit

By reversing the overflow tunnel build with two inputs and one output you get merging behavior that is slightly better than the T merge. If enough items are input this build will output items faster than a pulse conveyor can move items away.

Example Builds:Edit

Two-way Tunnel:Edit

This example tunnel build is just two normal 2 span tunnels overlapping. This can create a two-way conveyor for those moments when you are really out of space.

Interesting tunnel builds in action:Edit