Maintenance Tunnel
| “ | Prevents the decay of nearby structures when supplied. | „ |
| — In-game description |
The Maintenance Tunnel is a player-built structure designed to prevent the decay of nearby structures by consuming Maintenance Supplies in its stockpile. It can be configured to select the types of structures and the radius to prevent decay.
Construction
It can be built with a Hammer and costs 50 Basic Materials. Friendly Maintenance Tunnels are always visible on your map with a unique icon 
.
Reservation
The original builder can reserve it for a Squad 
for 52 hours in the menu to prevent non-members from modifying it, however the stockpile access is not restricted. The reservation can be refreshed 
by any squad member. If the reservation expires, the structure can never be reserved again. It counts as a facility so using the "Reserve Multiple" 
button on it will also reserve every other facilities built by the player and that share a common Foundation with it.
Demolition
The original builder, and squad members if reserved, can instantly demolish it 
if it was built less than 3 hours ago. The materials used in the construction are refunded and dropped under the player.
Destruction
It is immune to Friendly Fire but it can be flagged for "Disruptive Structure Placement" 
in its menu to remove the immunity (5 "votes" needed)
Structure Event Log
In its interface you can click the "View Actions Log" button 
to view a list of recent events, with timestamps and player names displayed. Events recorded include settings modifications. The log only displays the last 128 events (8 pages).
Use
Its interface can be accessed on foot or from the driver seat of a logistics vehicle by pressing E.
Storage
It has a single inventory slot and a stockpile that only accepts Maintenance Supplies (32k max).
Crates of Maintenance Supplies can be directly submitted into it, putting their contents into the stockpile.
In the interface you can view the Stockpile Actions Log to check what was added and retrieved from the stockpile.
You can check the content of a Maintenance Tunnel stockpile remotely by putting your cursor on its icon on the map.
Decay Prevention
It prevents the decay of nearby structures by consuming Maintenance Supplies placed in its stockpile. Unlike Bases, its menu allows you to manually adjust the supply range (between 0 and 100 meters) and filter the types of structures players want to protect from decay. The filter categories are:
- Defenses
(Pillboxes, Watch Towers, Walls, deployed Tripods, etc...) - Bunkers
(Trenches, Foxhole, Bunkers) - General
(Encampments, Storage Box, Fire Pit, Maintenance Tunnel, Field Bridge, Field Hospital, etc...) - Facilities
(Facilities except power related ones, Pipelines, Catwalks) - Mines
(player built Resource Mines) - Power
(Power Poles, Diesel Power Plant, Power Station). - Foundations
(Foundations, Small Gauge Railway Tracks, Railway Tracks, Provisional Roads, etc...) - Shippables
(all shippable structures, such as Emplacements, Ship Parts, Rocket Parts, etc...)
The Maintenance Tunnel consumes 1 Maintenance Supplies per hour per decaying structure, with some structures consuming more. The current hourly Maintenance Supplies consumption rate is displayed by putting your cursor on the tiny Maintenance Supplies icon in the top right of the menu.
A Maintenance Tunnel always try to prevent its own decay even if all filter categories are off.
Structures whose decay is actively prevented also get slowly repaired (1% health per hour) regardless of the damage source.
Trivia
- The model for the Maintenance Tunnel is the same as the old Tunnel Network
- Maintenance Tunnels were introduced in Update 1.50 (officially known as 'Inferno') in response to community concerns regarding Facilities and supplying them with enough Garrison Supplies (which later changed to Maintenance Supplies)
- They could only hold 1,000 Garrison Supplies
- When given Construction Materials and 2 MW of power, it could produce its own Garrison Supplies
Video Tutorial
Gallery
The menu of the Maintenance Tunnel
A fully constructed Maintenance Tunnel
• Assembly Materials II 
• Assembly Materials III 
• Assembly Materials IV 
• Assembly Materials V 
• Barbed Wire 
• Basic Materials 
• Coal 
• Coke 
• Components 
• Concrete Materials 
• Construction Materials 
• Damaged Components 
• Diesel 
• Enriched Oil 
• Explosive Powder 
• Gravel 
• Heavy Explosive Powder 
• Heavy Oil 
• Metal Beam 
• Oil 
• Petrol 
• Pipe 
• Processed Construction Materials 
• Rare Alloys 
• Rare Metal 
• Refined Materials 
• Salvage 
• Sandbag 
• Steel Construction Materials 
• Sulfur 
• Thermal Shielding 
• Unstable Substances 
• Water 
