Cement Log Bunker Army

a. Fighting Positions. Two or more individuals armed with rifles or machine guns design the following two positions for use. Although these are beyond the construction capabilities of nonengineer troops, certain construction phases can be accomplished with little or no engineer assistance. For example, while engineer assistance may be necessary to build steel frames and cut timbers for the roof of a structure, the excavation, assembly, and installation are all within the capabilities of most units. Adequate support for overhead cover is extremely important. The support system should be strong enough to safely support the roof and soil material and survive the effects of weapon detonations.

(1) Wood- or steel-frame fighting position. The wood- or steel-frame fighting position (Figure 2-17) consists of prefabricated timber or steel-frame support elements that support a timber or concrete roof. The position is useful as a two-soldier fighting or observation position in areas where it is dug in.

Overhead Protection For Soldier Shelters
Figure 2-17. Wood-Frame Fighting Position

(2) Fabric-covered frame position. A position constructed of a metal support frame covered with a strong fabric material is very effective as a support system for overhead cover. It also provides substantial levels of protection from blast and fragmentation. With 1 1/2 feet of overhead cover, this position survives detonation of a contact burst 82-millimeter mortar shell on the roof. Similar structures made from harder materials (wood, concrete, landing mat) require 2 1/2 feet of cover material for the same level of protection, due to lack of resilience of the harder materials. The position shown in Figure 2-18 is useful as a one- or two-solder fighting position. If the rear wall is omitted, AT weapons can be fired from this position.

Figure 2-18. Fabric-Covered Frame Position

b. Bunkers. Bunkers are larger fighting positions constructed for squad-sized units who are required to remain in defensive positions for a longer time. They are built either aboveground or belowground and are usually made of reinforced concrete. Because of the extensive engineer effort required to build bunkers, they are usually made during strongpoint construction. If time permits, bunkers are connected to other fighting or supply positions by tunnels. Prefabrication of bunker assemblies affords rapid construction and placement flexibility. Bunkers offer excellent protection against direct-fire and indirect-fire effects and, if properly constructed with the appropriate collective protection equipment, they provide protection against chemical and biological agents.

(1) Typical bunker. See Appendix E, page E-17, for information and an illustration about typical bunkers.

(2) Log fighting bunker with overhead cover. See Appendix E, page E-17, for information and an illustration about log fighting bunkers with overhead cover.

(3) Corrugated-metal fighting bunker. A bunker made from corrugated-metal (Figure 2-19) walls is very useful in areas where digging is not possible. With 1 1/2-foot-thick earth-filled walls and 2 1/2 feet of overhead cover, this position defeats direct fire and blast and fragments from near-miss mortar and artillery shells. For more protection, sandbags are stacked or loose earth is pushed up against the walls. The upper portion of the structure is left open for maximum visibility in all directions. Firing ports are located in the walls near the floor.

Concrete Cut And Cover Bunker
Figure 2-19. Corrugated-Metal Fighting Bunker

(4) Plywood perimeter bunker. See Appendix E, page E-19, for information and an illustration about plywood perimeter bunkers.

(5) Concrete log bunker. See Appendix E, page E-19, for information and an illustration about concrete log bunkers.

(6) Precast concrete-slab bunker. The precast concrete-slab bunker (Figure 2-20) is designed for use where aboveground construction is needed, but it is usually placed partially or completely belowground. The rectangular panels are designed for shop fabrication on a large-scale basis. Engineer support is required for fabrication and installation. This bunker provides excellent protection, especially if sandbags are stacked or loose earth is pushed up against the walls. When used as an observation bunker, the observation ports are enlarged to include firing ports near the floor.

Concrete Arch Fighting Bunker Design
Figure 2-20. Precast Concrete-Slab Bunker

(7) Concrete-arch bunker. The concrete-arch bunker (Figure 2-21) is a four-soldier fighting position adapted from the concrete-arch shelter. The bunker consists of three precast reinforced concrete components: a 6-foot-high arch section, a rectangular back wall section, and a semicircular roof section. Significant engineer support is required to construct and emplace this bunker. Placing a layer of sandbags against the walls increases fragmentation protection.

Concrete Arch Fighting Bunker Design
Figure 2-21. Concrete-Arch Bunker

c. Shelters. Shelters are primarily constructed to protect soldiers, equipment, and supplies from enemy action and the weather. Shelters differ from fighting positions because there are usually no provisions for firing weapons from them. However, they are usually constructed near (or to supplement) fighting positions. When available, natural shelters such as caves, mines, or tunnels are used instead of constructing shelters. Engineers are consulted to determine the suitability of caves and tunnels. The best shelter is usually one that provides the most protection but requires the least amount of effort to construct. Shelters are frequently prepared by support troops, troops making a temporary halt due to inclement weather, and units in bivouacs, assembly areas, and rest areas. Shelters are constructed with as much overhead cover as possible. They are dispersed and limited to a maximum capacity of about 25 soldiers. Supply shelters are of any size, depending on the location, time, and materials available. Large shelters require additional camouflaged entrances and exits. Three types of shelters (belowground, aboveground, and cut-and-cover) are usually sited on reverse slopes, in woods, or in some form of natural defilade such as ravines, valleys, wadis, and other hollows or depressions in the terrain. They are not constructed in paths of natural drainage lines. All shelters require camouflage or concealment. As time permits, shelters are continuously improved.

(1) Belowground shelter. Belowground shelters require the most construction effort but generally provide the highest level of protection from conventional, nuclear, and chemical weapons.

(2) Aboveground shelter. Aboveground shelters provide the best observation and are easier to enter and exit than belowground shelters. They also require the least amount of labor to construct, but are hard to conceal and require a large amount of cover and revetting material. They provide the least amount of protection from nuclear and conventional weapons; however, they do provide protection against liquid droplets of chemical agents. Aboveground shelters are seldom used for personnel in forward combat positions unless the shelters are concealed in woods, on reverse slopes, or among buildings. Aboveground shelters are used when water levels are close to the ground surface or when the ground is so hard that digging a belowground shelter is impractical. The following shelters are suitable for a variety of uses where troops and their equipment require protection, whether performing their duties or resting.

• Two-soldier sleeping shelter. The design for a two-soldier sleeping shelter (Figure 2-22) is very simple and is constructed without engineer support. Culvert sections used in the design are delivered in large quantities by truck or helicopter and then are hand carried to specific installation sites by the intended occupants working in teams of two. These shelters provide good protection from direct-fire small-caliber mortars (60 and 82 millimeter), machine guns below 12.7 millimeter in size, indirect-fire fragmentation, and grenades. With additional cover, the protection level increases to include larger direct-fire projectiles. The low profile of the structure makes it a difficult target to hit.

Figure 2-22. Two-Soldier Sleeping Shelter

• Metal culvert shelter. See Appendix E, page E-20, for information and an illustration about metal culvert shelters.

• Metal shipping container shelter. See Appendix E, page E-20, for information and an illustration about metal shipping container shelters.

• Air-transportable assault shelter. See Appendix E, page E-21, for information and an illustration about air-transportable assault shelters.

• Timber post buried shelter. See Appendix E, page E-21, for information and an illustration about timber post buried shelters.

• Modular timber frame shelter. See Appendix E, page E-22, for information and an illustration about modular timber frame shelters.

• Timber frame buried shelter. See Appendix E, page E-22, for information and an illustration about timber frame buried shelters.

• Aboveground cavity wall shelter. See Appendix E, page E-23, for information and an illustration about aboveground cavity wall shelters.

• Steel frame, fabric-covered shelter. See AppendixE, page E-23, for information and an illustration about steel frame, fabric-covered shelters.

• Hardened frame, fabric shelter. See Appendix E, page E-24, for information and an illustration about hardened frame, fabric shelters.

• Rectangular fabric, frame shelter. See Appendix E, page E-24, for information and an illustration about rectangular fabric, frame shelters.

• Concrete-arch shelter. See Appendix E, page E-25, for information and an illustration about concrete arch shelters.

• Metal pipe arch shelter. See Appendix E, page E-25, for information and an illustration about metal pipe arch shelters.

(3) Cut-and-cover shelter. Cut-and-cover shelters are partially dug into the ground and backfilled on top with as thick a layer of cover material as possible. These shelters provide excellent protection from the weather and enemy action. See Appendix E, page E-18, for an illustration of a cut-and-cover shelter.

d. Protective Walls. Several basic types of walls are constructed to satisfy weather, topographical, tactical, and other military requirements. The walls range from simple walls, constructed with hand tools, to more difficult walls requiring specialized engineering and equipment capabilities. Protection provided by the walls is restricted to stopping fragment and blast effects from near-miss explosions of mortar, rocket, or artillery shells; some direct-fire protection is also provided. Overhead cover is not practical due to the size of the position surrounded by the walls. In some cases, modification of the designs shown will increase nuclear protection. The effectiveness of the wall substantially increases by locating it in adequately defended areas. The walls need close integration with other forms of protection such as dispersion, concealment, and adjacent fighting positions. The protective walls should have the minimum inside area required to perform operational duties. Further, the walls should have their height as near to the height of the equipment as practical.

(1) Earth walls. Earth walls (Figure 2-23) are constructed entirely of compacted earth fill. The sides have a 1:1 slope (or 45°); therefore, a large area and constant maintenance are required, particularly in locations with high rainfall rates. A waterproof covering or sandbags are recommended to stabilize this type of protective wall.

Figure 2-23. Earth Walls

(2) Earth wall with revetment. An earth wall with a revetment (Figure 2-24) is a wall constructed of soil placed at a 1:1 slope against a revetment. Normally, the revetment is located on the inside of the wall as close as possible to the protected equipment. The height of the wall should be at least equal to the equipment protected.

Figure 2-24. Earth Wall With Revetment

(3) Soil cement wall. See Appendix E, page E-26, for information and an illustration on soil-cement walls.

(4) Soil bin wall with log revetment. See Appendix E, page E-26, for information and an illustration on soil bin walls with log revetments.

(5) Soil bin wall with timber revetment. See Appendix E, page E-26, for information and an illustration on soil bin walls with timber revetments.

(6) Soil bin wall with plywood revetment. See Appendix E, page E-27, for information and an illustration on soil bin walls with plywood revetments.

(7) Plywood portable wall. See Appendix E, page E-27, for information and an illustration on plywood portable walls.

(8) Steel landing mat wall. See Appendix E, page E-27, for information and an illustration on steel landing mat walls.

(9) Portable precast-concrete wall. A portable precast-concrete wall (Figure 2-25) provides a versatile portable, and durable wall for protecting essential equipment, living quarters, hospitals, administration buildings, and parked vehicles. Its modular construction permits a wide variety of configurations and applications. The wall is made of 6-inch thick, 8-foot long reinforced concrete panels supported by two concrete footings. Protection provided is less than 1-foot-thick soil bin walls, but is improved by stacking sandbags against the outer face of the panels.

Figure 2-25. Portable Precast-Concrete Wall

(10) Cast-in-place concrete wall. A cast-in-place concrete wall (Figure 2-26) provides excellent protection but requires skilled workers and special equipment at the construction site. As with the portable concrete wall previously described, protection is greatly improved by placing a layer of sandbags against the outer wall surface.

Figure 2-26. Cast-in-Place Concrete Wall

(11) Portable asphalt armor panels. Portable asphalt armor panels (Figure 227) are used for siding on buildings or as protective panels for military equipment and vehicles. Panels are 2 feet wide by 8 feet long and 2 and 4 inches thick. Engineer troops are required to construct the panels and properly prepare the asphalt mixture. The thin panels stop fragments from mortar shells exploding 30 feet away and the thicker panels at a distance of 5 feet.

Figure 2-27. Portable Asphalt Armor Panels

2-8. Checkpoint Construction. Checkpoints are established to control the movement of personnel and vehicles across a battlefield and preventing illegal actions or actions that aid the enemy. Checkpoints are either hasty (temporary, see Appendix E, page E-28) or deliberate (permanent, see Appendix E, page E-28 and Figure 2-28). They may also be used to—

• Ensure that classified routes carry only authorized traffic.

• Prevent enemy sympathizers from supplying the enemy with food, medicine, ammunition, or other items of military use.

• Prevent black market transportation of contraband.

Use shicane or a Passive vehicle Retaining concrete barrier to barriers as iane fence Inspection reduce vehicle speed separators / / area 2

"Checkpoint Ahead" sign

Inspection Area 1

■Vehicle and personnel holding area

Use shicane or a Passive vehicle Retaining concrete barrier to barriers as iane fence Inspection reduce vehicle speed separators / / area 2

"Checkpoint Ahead" sign

Inspection Area 1

■Vehicle and personnel holding area

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