Trench & Bunker Construction System

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Foxhole has a dynamic modular base building system that allows Players to build Trench & Bunker networks. It relies on foundational Trench & Bunker segments that can be connected together and automatically snap to each other. When Bunker segments are connected the wall between them disappears forming a Bunker Network. Multiple Bunker Networks can be connected together using Trenches to form Trench Networks. Individual Trench and Bunker segments can be modified and upgraded to add new functionalities (Barbed Wire, Stairs, Doorway, Garrisoned defenses, utility structures, Forward Base, etc...). The system also has three tiers, individual segments can be upgraded to increase their health and Damage Resistance.

Foundational Segments

A trench & bunker base always start by placing the blueprints of foundational segments. They automatically snap to each other at certain points. The snapping can be disabled by holding Shift during placement. Once placed, the Build Sites must be dug with a Shovel. The different types of foundational segments include:

Tier

Each Bunker and Trench segment can be upgraded to Tier 2 with a Hammer and some Basic Materials, and to Tier 3 with Concrete Materials. For bunker segments with structure upgrade, certain Base Upgrades might be necessary at the connected Bunker Base.

For Tier 3, the concrete must dry off for 24 hours before a Structure Upgrade modification can be added. The duration increases during Snow Storms and Rain Storms depending on their intensity (up to double with highest intensity). While very sturdy when dry, concrete is vulnerable while still wet. The vulnerability depends on how wet the concrete is and functions as a damage multiplier. Wet concrete that's just been placed has a x10 damage multiplier compared to dry concrete. After 8 hours the damage multiplier is roughly x3, and x2 after 12 hours.

Upgrades

Modifications can be added to Bunker and Trench segments with a Hammer in "Upgrade" mode (switch with F), press E to open the upgrade menu.

Small Modifications

Adding a Small Modification makes the player's character perform a short construction animation after which the modification appears. The materials will automatically be taken from the player's inventory. Use Mouse Wheel to select the orientation and position of the Small Modification when relevant. They can be removed by pressing Right Click on their icon option in the upgrade menu instead of Left Click. The modifications available for a Bunker or Trench segment depends on its type. The structure upgrade installed on a Bunker piece can also prevent the placement of certain small modifications (e.g. Engine Room vs Ladder).

Bunker Modifications:

Name Icon Description Available For Cost Removal Cost
Doorway BunkerT1DoorwayIcon.pngFortT2DoorIcon.pngBunkerT3DoorwayIcon.png Provides entry into this Bunker. Bunker
Bunker Corner
20 BasicMaterialsIcon.png 10 BasicMaterialsIcon.png
Firing Port BunkerT1FiringPortIcon.pngFortT2WindowIcon.pngBunkerT3FiringPortIcon.png Allows infantry weapons to be fired from the safety of this bunker.
Allows a Mounted Weapon to be installed (90° firing arc) and gives an inventory to store the weapon's ammo.
Warning: The weapon installed can be used by enemies if the bunker piece is neutral!
Bunker
Bunker Corner
1 MetalBeamMaterialItemIcon.png 20 BasicMaterialsIcon.png
Interior Firing Port FortT3InteriorFiringPortItemIcon.png Provides cover against enemies that have entered this Bunker. Tier 3 Bunker 10 BasicMaterialsIcon.png 5 BasicMaterialsIcon.png
Stairs FortT2StairItemIcon.png Allows easy access to the roof of this bunker. Tier 2 & 3 Bunker
Tier 2 & 3 Bunker Corner
30 BasicMaterialsIcon.png 15 BasicMaterialsIcon.png
Ladder FortT2Roof02ItemIcon.png Permits access into this Bunker from the roof. Tier 2 & 3 Bunker 20 BasicMaterialsIcon.png 10 BasicMaterialsIcon.png
Sandbags SandbagsStructureIcon.png Bunker Sandbags gives a secure firing position on the roof while preventing enemies from climbing onto your bunker.
Can only be placed on the exterior sides of the Bunker
Tier 2 & 3 Bunker
Tier 2 & 3 Bunker Corner
1 SandbagMaterialItemIcon.png 20 BasicMaterialsIcon.png

Trench Modifications:

Name Icon Description Available For Cost Removal Cost
Barbed Wire BarbedWireDay.png Slows the enemy infantry attempting to invade this Trench.
The length covered by one Barbed Wire depends on the Trench type.
Trench
Trench Connector
Trench Intersection
Trench Emplacement
1 x BarbedWireMaterialItemIcon.png 20 x BasicMaterialsIcon.png
Berm TrenchSandbagItemIcon.png A defensive barrier that hinders enemy movement and provides cover during combat. Soldiers in the trench cannot shoot over it.
The length covered by one Sandbag depends on the Trench type.
Trench
Trench Connector
Trench Intersection
Trench Emplacement
1 x SandbagMaterialItemIcon.png 20 x BasicMaterialsIcon.png
Bridge TrenchBridgeIcon.png Allows vehicles to cross over this Trench. Trench 1 x MetalBeamMaterialItemIcon.png 20 x BasicMaterialsIcon.png
Stairs TrenchT3Ramp.png Provides easy access into and out of this Trench. Trench 30 x BasicMaterialsIcon.png 15 x BasicMaterialsIcon.png
Hard Point OneWayTrenchItemIcon.png A defensive position that blocks movement in one direction. Trench (connected to another) 30 x BasicMaterialsIcon.png 15 x BasicMaterialsIcon.png
Trench Roof TrenchT3RoofItemIcon.png Provides cover against enemies that have entered this Bunker.
Does not act as a Bridge.
Tier 3 Trench
Tier 3 Trench Connector
Tier 3 Trench Intersection
200 x BasicMaterialsIcon.png unremovable

Infrastructure Modifications

An Infrastructure Modification can be installed inside a Tier 2 or Tier 3 Bunker or Bunker Corner segment if it is connected to a Bunker Base by Trenches or Bunkers (up to a maximum range of 40 pieces). It must not conflict with another modification (Engine Room, Firing Port) and must have a wall to rest on (e.g. not in the middle of a 3x3 bunker network). It costs 50 Basic Materials BasicMaterialsIcon.png to install and 25 Basic Materials BasicMaterialsIcon.png to remove, no matter the kind. Each bunker piece can only have one. Use Mouse Wheel to select the desired position during placement.

Infrastructure modifications are either of the type Garrison IconInfrastructureGarrison.png or Command IconInfrastructureCommand.png. They contribute to the Infrastructure requirement to unlock the Base Upgrades at all the Bunker Bases connected to them by Trenches and Bunkers, up to a maximum range of 40 pieces (including the Bunker where the infrastructure is and the Bunker Base).

They also contribute different bonuses to all the bunkers connected to them (40-piece range as well). A bunker loses the bonus if its connection to the relevant Infrastructure Modification is severed.

Some kinds of infrastructure modifications only become available after a certain amount of infrastructure modifications of the same infrastructure type have already been built in the network of connected bunkers and trenches.

Garrison Infrastructures IconInfrastructureGarrison.png

They are needed to unlock Defensive Garrisons (Tier 1) InfantryGarrisons.png (4), Defensive Garrisons (Tier 2) InfantryGarrisons02.png (12), Defensive Garrisons (Tier 2) InfantryGarrisons02.png (24), and (30).

Name Icon Bonus Type Required Modifications
Bunks FortImodBunkBedIcon.png +1% chance for a soldier not to consume Soldier Supplies upon respawning (max 10%) None
Lockers FortImodLockerIcon.png None
Latrine FortImodLatrineIcon.png 5 IconInfrastructureGarrison.png
Wash Station FortImodDishwashStationIcon.png +1% fire rate to AT Gun Garrisons (max 20%) and +3.33% to Artillery Garrisons (max 66.6%) 10 IconInfrastructureGarrison.png
Kitchen FortImodKitchenIcon.png 15 IconInfrastructureGarrison.png
Pantry FortImodPantryIcon.png 15 IconInfrastructureGarrison.png
Command Infrastructures IconInfrastructureCommand.png

They are needed to unlock Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png (6), Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png (12), Deployment Point IconFacilitiesDeploymentPoint.png (24), and Advanced Bunkers AdvancedBunkerIcon.png (40).

Name Icon Bonus Type Required Modifications
Workstation FortImodDeskIcon.png -1% power cost of Storm Cannons, Intelligence centers, or Weather Station (max 20%) None
Computer Module FortImodModuleIcon.png None
Radio Station FortImodRadioStationIcon.png +1% range to Observation bunkers (max 20%) (Not shown on the intel circle size on the map) 10 IconInfrastructureCommand.png
Chalk Board FortImodChalkBoardIcon.png 10 IconInfrastructureCommand.png
Strategic Map FortImodStrategicMapIcon.png 15 IconInfrastructureCommand.png

Structure Upgrades

A square Bunker segment can be modified into various specialised structures. Only one Structure Upgrade can be installed and it cannot be removed once built. It deletes all Small Modifications and Infrastructure Modifications that are in conflict with it (e.g. sandbags & ladder add-ons removed when placing a bunker garrison, or infrastructure modification removed when placing an engine room).

Most Structure Upgrades require that the Bunker is connected by trenches or bunkers to a Bunker Base with certain base upgrades unlocked. The direct chain of bunkers and trenches linking them must have 40 or fewer pieces (including the Bunker itself and the Bunker Base).

The Bunker must have full health (and be dry if it has concrete) to install a Structure Upgrade.

The upgrade's impact on its Bunker Network's Max Health and Breachable Health is mentioned in the description.

Name Icon Description Requirements
Bunker Base FortT1BaseIcon.pngFortT2BaseIcon.pngFortT3BaseIcon.png A large forward operating base. Players can spawn and stockpile items here. Built with a Construction Vehicle Only on Tier 1 bunkers.
Only one per Bunker Network
Cannot be adjacent to a garrison Upgrade, even diagonally.
Bunker Ramp FortT1RampIcon.pngFortT2RampIcon.pngFortT3RampIcon.png A ramp that provides access to underground Bunkers.
Rifle Garrison FortT1GunAIIcon.pngFortT2GunAIIcon.pngFortT3GunAIIcon.png An entrenched bunker manned by stationed troops armed with Rifles. Defensive Garrisons (Tier 1) InfantryGarrisons.png
Defensive Garrisons (Tier 2) InfantryGarrisons02.png
Defensive Garrisons (Tier 3) InfantryGarrisons03.png
Machine Gun Garrison FortT1MGunAIIcon.pngFortT2MGunAIIcon.pngFortT3MGunAIIcon.png An entrenched Machine Gun emplacement manned by stationed troops. Defensive Garrisons (Tier 1) InfantryGarrisons.png
Defensive Garrisons (Tier 2) InfantryGarrisons02.png
Defensive Garrisons (Tier 3) InfantryGarrisons03.png
AT Gun Garrison FortT1ATGunAIIcon.pngFortT2ATGunAIIcon.pngFortT3ATGunAIIcon.png An entrenched AT gun manned by stationed troops. Defensive Garrisons (Tier 1) InfantryGarrisons.png
Defensive Garrisons (Tier 2) InfantryGarrisons02.png
Defensive Garrisons (Tier 3) InfantryGarrisons03.png
Observation Bunker ObservationBunkerT1Icon.pngObservationBunkerT2ItemIcon.pngObservationBunkerT3ItemIcon.png A radio bunker that provides intel to friendly units about the surrounding area. Reinforced with wood, it can withstand more punishment than a standard radio tower, and therefore is capable of increased effectiveness. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png
Engine Room EngineRoomIcon.png An engineering facility that provides power to Bunker structures using pipe connections. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png

Only on Tier 2 and Tier 3 bunkers.

Fire Suppression Room FortFlameStructureIcon.png A bunker with a mechanical station that will automatically spray water in the event of a fire. Includes a pipe connection. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png

Only on Tier 2 and Tier 3 bunkers.

Medical Room FrotModMedicalRoomIcon.png A medical bunker used to treat critically wounded soldiers at the front line. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png
Artillery Shelter Room FortArtilleryShelterIcon.png A sheltered bunker that improves the resistance against artillery of adjacent bunkers at the cost of structural integrity. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png

Only on Tier 2 and Tier 3 bunkers.

Storage Room AmmoRoomIcon.png A Bunker Room designed to hold large amounts of large items. Crates of these items can be directly submitted. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png

Only on Tier 2 and Tier 3 bunkers.

Bunker Hearth FortFirePitIcon.png A hearth that warms up soldiers during Snow Storms when fueled with Diesel. Support Bunkers (Tier 1 & Tier 2) ObservationBunkerT2ItemIcon.png
Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png
Artillery Garrison FortT1HowitzerAIIcon.pngFortT2HowitzerAIIcon.pngFortT3HowitzerAIIcon.png An entrenched Howitzer emplacement manned by station troops. Defensive Garrisons (Tier 1) InfantryGarrisons.png
Defensive Garrisons (Tier 2) InfantryGarrisons02.png
Artillery Garrisons (Tier 3) FortT3HowitzerAIIcon.png
Large Structure Foundation EMPT3Icon.png A structural foundation for the building of Storm Cannons, Intelligence Centers, Weather Stations, and Underground Fortresses. Support Bunkers (Tier 3) ObservationBunkerT3ItemIcon.png

Only on Tier 3 bunkers.
Cannot be adjacent to another garrison Upgrade, even diagonally.
Requires a 3 by 3 bunker network.

Bunker Network

A Bunker Network (or Bunker Island) is formed when Bunker segments are joined together. The walls between each Bunker disappear and the bunkers pool together their health. Bunkers connected by a Trench are not part of the same Bunker network. Multiple game mechanics are unique to Bunker Networks.

Health

When a Bunker is attached to an existing Bunker Network, its health is shared with the network. However this also decreases the network's Structural Integrity, a numerical value between 0 and 1. The Max Health of a bunker network is equal to the sum of the health of each of its bunker segment multiplied by the Structural Integrity (only when the network has more than one bunker).

Each bunker segment inside the network has a multiplier that affects the Structural Integrity. It depends on the Structure Upgrade installed on it:

Structure Modifier
Large Structure Foundation 1
Underground Fortress 0.99
Bunker, Bunker Corner, Bunker Ramp, Bunker Hearth, Storage Room, Engine Room, Medical Room, Fire Suppression Room 0.97
Observation Bunker 0.9
Machine Gun Garrison 0.89
Rifle Garrison 0.86
AT Gun Garrison, Artillery Shelter Room 0.82
Artillery Garrison 0.74
Bunker Base 0.7
Storm Cannon, Intelligence Center, Weather Station 0.65

The Structural Integrity is equal to the product of the multiplier of each bunker piece in the network plus a "compactness" bonus. The compactness bonus is equal to 0.15 * A / B where A is the number of edges that are not touching the exterior and not between two touching bunker garrisons while B is the total number of edges in the Bunker Network (see the illustration below).

The health and structural integrity of a Bunker Network explained

The compactness bonus also cannot be higher than the Structural Integrity without that bonus (only relevant at extremely low integrity).

As an example, a Bunker Network that is a line of 3 pieces with Rifle Garrison - Bunker - AT Gun Garrison will have a Structural Integrity equal to 0.86*0.97*0.82+0.15*2/10 = 0.714 since the bunker network has 2 good edges out of 10 (1 between the Rifle Garrison and the Bunker and 1 between the AT Gun Garrison and the Bunker).

When modifying a bunker, each upgrade's description indicates the expected change to the Bunker Network's Max Health if the upgrade is added.

Repair
Repairing a Bunker with a Hammer and some Basic Materials will repair the Network it is part of. The repair cost for the entire network is equal to the sum of repair cost of each Bunker in it (e.g. repair cost of a Tier 1 Bunker is 50 bmats so a network of three will require 150 bmats).

Given the mechanic of Structural Integrity, repairing a fixed amount of damage (e.g. one RPG) becomes more expensive the larger the Bunker Network is.

Destruction
When a Bunker Network's health reaches zero every Bunker segment in it is destroyed, each leaving behind a rebuildable husk.

Breach

A Bunker segment that is part of a Bunker Network can be breached and collapse, creating a new entrance point for soldiers to enter the Bunker Network's interior. The breached bunker piece is separated from the Bunker Network. It behaves exactly like a bunker husk, it can be destroyed or rebuilt, except the reconstruction requires that its old Bunker Network be at full health.

A breach has a chance to occur when a bunker piece is hit by enemy Explosive, High Explosive, or Demolition damage while its Bunker Network's health is below a percentage called Breachable Health. The chance to breach starts below the Breachable Health and increases the lower the health is. Certain types of ammunition have an increased chance to cause a breach (250mm “Fury” Shell, 250mm “Purity” Shell, Alligator Charge, Havoc Charge, Hydra's Whisper, Shatter Missile). A few ammo types bypass the requirement and can cause a breach regardless of health level (250mm “Fury” Shell, 300mm, Havoc Charge, Shatter Missile).

The Breachable Health percentage is equal to inverse of the Structure Integrity (including the compactness bonus), i.e. 1-Structural_Integrity. If a Bunker Network's Structural Integrity is 0.7 then its Breachable Health is equal to 0.3 or 30% of Max Health. A Bunker Network's Breachable Health can be viewed by aiming at it with any construction tool in Upgrade Mode (switch with F).

Weapons that can cause breaches always roll to breach Bunker segments with wet concrete with reducing chances as the concrete cures.

Bunker Base and Large Structure pieces cannot be breached.

For Bunker Networks that houses a Large Structure, if any piece is breached then the entire bunker network is destroyed. The destroyed Large Structure piece leaves a simple bunker husk, except for Storm Cannon which leave a unique Storm Cannon Husk.

Ammunitions with Custom Breaching Chance

Name Damage Explosion Radius Breaching Modifier Penetration Modifier Added Burning Weight In Crate
Shatter Missile DemolitionRocketAmmoIcon.png 250 SubtypeLRAIcon.png 5.5m (full dmg: 2.25m) 0.7x 400 1
Alligator Charge SatchelCharge.png 400 SubtypeLRAIcon.png 2m 3x 385 10
Havoc Charge ExplosiveTripodIcon.png 1950 SubtypeLRAIcon.png 7m (full dmg: 6m) 3x 385 5
Hydra's Whisper BangaloreItemIcon.png 550 SubtypeLRAIcon.png 2m 1.2x 125 5
250mm “Fury” Shell MortarTankAmmoBRIcon.png 787 SubtypeLRAIcon.png 5m (full dmg: 2.5m) 2x 300
250mm “Purity” Shell MortarTankIcon.png 787 SubtypeLRAIcon.png 5m (full dmg: 2.5m) 3x 300 5

Reserve Power

Engine Rooms can produce and store Reserve Power ReservePower.png for their Bunker Network and is used to power structures within it. Each Engine Room can store 100 Reserve Power and adds to the Bunker Network's total power storage capacity. The structures that consume Reserve Power are:

Structure Power Consumption
Rifle Garrison (T2 or T3) Spotlight at night: 0.001ReservePower.png/min (0.72/day)
Machine Gun Garrison (T2 or T3) Spotlight at night: 0.001ReservePower.png/min (0.72/day)
AT Gun Garrison (T2 or T3) Spotlight at night: 0.001ReservePower.png/min (0.72/day)
Observation Bunker (T2 or T3) 0.2ReservePower.png/min (288/day)
Fire Suppression Room Spraying Water: 0.125ReservePower.png/min (7.5/hr)
Storm Cannon Firing: 50ReservePower.png per shot
Rotating: 0.1ReservePower.png per degree
Intelligence Center Firing: 80ReservePower.png per shot
Rotating: 0.5ReservePower.png per degree
Weather Station Firing: 80ReservePower.png per shot
Rotating: 0.5ReservePower.png per degree

Faction Ownership

Bunkers are neutral by default but are faction-owned if they have a Structure Upgrade modification installed (except Bunker Ramp and Artillery Shelter Room). If a Bunker network has at least one Bunker with a Structure Upgrade installed then every Bunker in the network also stops being neutral and thus cannot be modified by the enemy (can't add or remove small modifications and Infrastructure modifications).

Garrison Retaliation

Bunker Garrisons that can retaliate (e.g. Rifle Garrison) will do so if any Bunker that is in the same network is damaged (not just hit).

Husk

When destroyed, Trench and Bunker segments leave behind a husk that can be either destroyed or rebuilt. Bunker segments that had a "room" Structure Upgrade (e.g. Engine Room) lose all modifications and leave a simple bunker husk while Bunker segments with exterior Structure Upgrade (e.g. Rifle Garrison) leave a husk with that upgrade. A segment's reconstruction uses the same tool and materials as the construction of its current tier and has the same requirements. A husk can be rebuilt by either faction however it cannot be rebuilt if it is connected by Trench or Bunker to an enemy Bunker Base (direct chain of fewer than 40 pieces, counting the bunker base piece, and also includes husked and breached pieces). The reconstruction restores all small modifications and infrastructure modifications installed inside at no cost.

Bunker and Trench husks can be used for cover by the attacking side. Some bunker husks can be climbed.

Bunker&Trench Connections

Every Trench and Bunker physically connected to a Bunker Base form a network. The network starts at the Bunker Base and reaches every connected bunker and trench for which the shortest connection to the bunker base is a chain of 40 trench/bunkers or less (including themselves and the bunker base). Husked and breached Trenches and Bunkers also count as valid connections for the network, but blueprints (except for upgrade blueprints) do not. The following effects are spread throughout this network:

  • Faction Ownership: Bunkers and Trenches in the network cannot be modified by the opposing faction.
  • Base Upgrades: Base Upgrades unlocked by the Bunker Base apply throughout the network. They allow connected Bunkers to be modified into the various bunker garrisons unlocked. Once a bunker has been modified into a bunker garrison it won't lose its modification if it's disconnected from the network.
  • Infrastructure: Infrastructure Modifications installed in the network's bunkers count towards the infrastructure requirements to unlock certain Base Upgrades at the Bunker Base.

When a player is inside a bunker or trench segment they can see the interior of every segment connected to it. They can hold Ctrl if they want to view the roofs of the connected segments.

Tactics

Bunker Network should always be built as compact as possible to improve their structural integrity and thus their health and breachable health. Example:

Trivia

  • The Trench & Bunker Construction System was introduced in 0.32 Trench Warfare and provided a brand new way of building defenses.

Gallery

Video Guide

A video guide made by Freerk.