Perimeter Security [Part Three]


Perimeter PatrolPatrolling Outer Perimeter (Fence Line) and Buffer Zone are important in maintaining security

If you have not read Part One and/or Part Two of the Perimeter Security series of articles, you may want to consider navigating to and reading them first, by clicking (or touching) on the two links below:

[Part One]   [Part Two]

The Perimeter Security series of articles are logical extensions of the original Perimeter & Security article, which was written and built on top of publications like the US Physical Security Field Manual. The Perimeter & Security article introduced the concept of establishing perimeter (zones) around your building (home, safe house or retreat) to enhance your physical security posture.

The Perimeter & Security article was designed to integrate the idea of

  1. Establishing a level of Physical Security at your premise, and
  2. Extending (and improving) your safety by creating (and extending) additional zones outside of the your premise.


Part One introduces the concept of a four (4) tiered security model. In this model, your premise (Buildings, as in Home / Shed / Safe House / Retreat / BOL) is the in the center (Objective) of this model. The proposed Zones are built around the Objective using a series of concentric “rings” that are your Inner Perimeter, Outer Perimeter and Buffer Zone(s) in this model.

The concentric ring model is by far the simplest model for zonal defense. When applied properly, it can provide a significant increase to the level of security and defensibility against most (civilian) intruders that are not equipped with armor or ordnance.

In Part Two of the series, we dwell deeper into our zone based Perimeter Security Theory. Part Two begins to go into more technical detail about concentric perimeters, and introduces the first of the Security and Control Tools for your consideration:

  1. The Bollard
  2. Wire Security Fencing and Entanglement

Part Two briefly describe how Bollards and Fencing and Entanglement are deployed in modern security designs. Both these tools can be used as an integral part of your defensive strategy. They can enhance your security at your Entry (Ingress), Exit (Egress) points and along your footpaths and roadways leading to and through your Inner & Outer Perimeter and Buffer Zone(s). These Security and Control Tools serves as mechanisms to:

  1. Control Access (Prevent Break & Enter, Theft or Robbery from occurring)
  2. Control & Direct Flow of Traffic (For Controlling or Directing People and/or Vehicles)
  3. Prevent Vehicle Intrusion (Prevent Intruders from using Heavy Machinery or Vehicles for Entry)
  4. Deny Route (By Putting In or Removing Physical Infrastructure(s) to Prevent Passage)
  5. Deny Area (By Using Structures or Excavation to Prevent Access to Protected Areas)
  6. Fortify & Harden (By Building Structures to Protect Inhabitants & Defenders from Intruders)
  7. Detect & Observe (By Proactively Mitigate Risk by Preventing Insurgency, Infiltration, Sabotage)
  8. Create Countermeasures (By Creating Hazards to route / delay / prevent Human & Vehicular Intrusion)

This is Part Three of the Perimeter Security series. This article builds on Part One and Part Two of this series. We will continue to explore more types, design and application of Security and Control Tools.

Security and Control Tools, Continued

Continuing on with the Access Control and Area Denial aspect of Physical Security and Control Tools, this article we will look at:

Trenches & Pits

Trench using backhoe

Trenches can be used strategically to enhance your Perimeter Security Strategy

Trenches & Pits can be used in many different ways to help secure your Home / Safe House /Retreat / BOL. Creating one or more trenches or pits are indeed simple, and they certainly are the least expensive and most useful DIY to implement in a Perimeter Security Strategy. (You can use machinery or human sweat to make it work. You can use these Trenches & Pits to:

  1. Fortify Positions
  2. Access Denial & Countermeasures
Fortify Positions

A network of trenches behind a high fence, in a slightly elevated position (inside the Outer Perimeter) will offer minimal exposure to small arms fire. trenches that are fortified will provide safe travel corridors for defender if your location is under attack.

Why consider trenches? Trenches have been effective for armed conflicts over the past 100 years, beginning with WWI, through WWII, Korean War, Vietnam War and numerous other armed conflicts thereafter. Armies dig trenches for safety and fortification because they work.

Cross section of TrenchTrenches used in WWI to provide cover for Soldiers

Access Denial & Countermeasure

Trenches and Pits can also be deployed as highly effective countermeasures. We will look into some examples of how they can be used as Area (Access) Denial Mechanisms:

Pit Traps

Pit Traps are probably one of the simplest variant of traps.


Pit Trap 4


Pit Trap  2



Pit Trap 3


Pit Trap 5


Pungi Sticks are a form of pit trap that uses spikes, it will be discussed briefly in the Spikes section and the use of trenches and pit based traps will be covered in depth in the Countermeasures, scheduled in future Perimeter Security articles.


retractable spikes 2x

There are many types of spikes that serve different purposes. Generally speaking, some spikes are effective against soft skinned (unarmored) vehicles and others are designed to be deployed against humans (and on occasions, animals).

Retractable (Tire) Spikes

Retractable Tire Spikes are devices that can be mounted flush or above ground. Most retractable spikes typically are directional, where they are harmless to tires in one direction but would create serious damage to a vehicles tires if they travel in a contrary direction.

Retractable Spikes are often used to control the directional flow of vehicular traffic (at a minimum, at entry and exit points)

retractable spikes 3Retractable Tire Spikes

Spike Strips

Spike Strips are designed to be rapidly deployed, and are used i) to disable oncoming vehicles that are under pursuit, or they are used ii) to create road blocks and at checkpoints.


Magnum Spike Strip 16'16′ Portable Spike Strips


Magnum Spike Strip deployed

Portable Spike Strip Deployed



Caltrops are ancient weapons that goes back close to two thousand years (51 BC was when its use was first recorded). They are inexpensive, simple to make and dead easy to deploy. (Ed. Note: Due to some union activities in the 1970’s involving Caltrops (aka Jack Rocks) used in “controversial” actions. Some jurisdictions have made possession of Caltrops illegal. You definitely want to check before you start making quantities of Caltrops).


Caltrop 3Modern Day Caltrops used against Pneumatic Tires


Caltrop 4Modern Day Caltrops used as Antipersonnel Countermeasures


Caltrops are shaped and behaves a lot like the jacks used in children’s toys.

jacks toysJacks looks a lot like Caltrops

Developed and deployed as an antipersonnel weapon, made up of two or more sharp nails or spines arranged in such a manner that one of them always points upward and the other three (or more) points forms a stable base.

Caltrops is a easy to fabricate, low cost area denial weapon. Historically they were used slow the advance of cavalry (horses, camels, war elephants) and human foot soldiers. Modern caltrops are mainly used against humans and wheeled vehicles (with pneumatic tires).


Caltrop 1Hollow Caltrops for tires (OSS)


Caltrop 7

Modern Caltrops (US Military)


Caltrop 8 vietnam era

Vietnam Era (1960’s) Caltrops


Caltrop 10 in TireCaltrops used to puncture modern, air pressure (Pneumatic) tires

Here are a couple of Youtube videos on DIY Caltrops:

How to Make Jack Rocks AKA Caltrops

How to make Caltrops

Tank Traps

During WWII, large caltrop-shaped objects made from welded steel and / or reinforced concrete were used as “Tank Traps“. Tank Traps are rarely used to trap armored vehicles, they are large obstacles that are principally designed to i) deny access and ii) control the flow of armored (and often tracked) vehicles and tanks.

Caltrop 13 Tank Trap Omaha BeachTank traps on Normandy Beach (circa WWII)

Dragon’s Teeth

Dragons Teeth 2Dragon’s Teeth are used to Deny Tracked Armored vehicles access and acts as Bollards

Much more common were pyramid devices made of reinforced concrete called Dragon’s Teeth, which were designed to wedge into tank treads. Large ones are still in use today to deny access to wheeled vehicles, especially in camp areas.

Dragons Teeth 3Modern use of Dragons Teeth


Dragon Teeth-10


Dragons Teeth 4[/one_half_last]

Dragons Teeth are still seen all over Europe, farms exists where battlefields once stood

The German Axis were deviously ingenious during WWII, after the effectiveness of Dragons Teeth were well established with the Allied Tank Corps, they began to deploy Decoy Dragons Teeth as a mechanism to control the flow of armored vehicles.

Dragons Teeth Decoys Video

Another caltrop-like defence during World War II was the massive steel, freestanding Czech hedgehog; the works were designed as anti-tank obstacles, and could also damage landing craft and warships that came too close to shore. These were used by the Germans to defend beaches at Normandy and other coastal areas.

Run Flat Tires & Non Pneumatic Tires (NPTs)

Run FlatsStandard Run Flat Tires can withstand Caltrops & most Spike Strips

One of the nemesis of most spike based flow control or access / area denial systems are Run Flat Tires (Run Flats). These Run Flat Tires are designed and built to operate even after the tire has been depressurized. Run Flats are available as i) Reinforced Tire ii) Modular Core units and iii) Solid Core tires.

Depending on the type and level of protection offered, some of these tires can even operate when a significant portion of the tire has been damaged (i.e ripped or shot out).


Run Flats 4Modular core Run Flat Tires


Run Flats 5 Solid CoreSolid Core Run Flats


There are even solid rubber tires that are found in heavy vehicles, machinery and equipment:

Run Flats for Equipment

You will often find Run Flats on many modern military vehicles and some high end autos such as Hummer, BMW, Mercedes and Rolls Royce as well as custom built executive protection (armored limousines) and some trucks (tractor trailers).

Typically, the higher the risk or potential hazard, the greater the likelihood that the vehicle are equipped with modular or solid core run flat tires (and enhanced braking), some systems even have auto-inflation and self-sealing systems built -in to mitigate the damage.

Non Pneumatic Tires (NPTs) are new generations of run flat tires that are resistant to puncture and weakness associated with pneumatic (air pressure) tires. You can read our NPT article to learn more about this new generation of highly resilient, puncture proof tires.

Michelin NPT TweelNon Pneumatic Tires (NPTs) do not contain an inner tube or air inflation to operate

Youtube Video of NPT Tires on a Pickup Truck

Youtube of NPTs in use with Heavy Machinery

With constantly changing technology, perimeter security strategy needs to evolve to address these changes. Although NPTs are in limited circulation today, they are being adopted for military vehicles such as the Humvee and the new MRAPs. These military vehicles are resistant to many of the standards Route Denial Tools and Methods such as Tire Spikes, Caltrops, Fencing, Entanglements and even Anti-personnel Land Mines.

MRAP Humvee ReplacementMRAPs are Current Humvee replacements and they can withstand ordnance up to landmines

Pungi Sticks

Pungi Sticks perform a similar role to caltrops. Pungi Sticks is a form of trap made by creating putting sharpened sticks or spikes, placed vertically in the ground (made of bamboo, wood and sometimes metal) which may line the bottom (and occasionally the sides) of a camouflaged pit , trench or dead-fall. Fields of Pungi Sticks are sometimes emplace in plain sight .

Pungi Sticks 2A Pungi Stick Pit (concealed Boobytrap)

Pungi Sticks 1Pungi Stick Field (Emplacement)

Pungi Stick Video (Vietnam Museum)

Thank you for reading Part Three of Perimeter Security. We are working on Part Four already so it shouldn’t be too long before the next article although there are always a dozen or so articles we are researching / collaborating /editing and working on.

After reviewing our materials for this series, we concluded that this is going to be a pretty long series. There is so much materials we’d want cover and share. There is also a fair bit of vetting of the contents for Relevancy in Preparedness

If you like what you read, please use our Social Networks Share Widget (above and below the body of the article) to share with your friends. It’s definitely appreciated. Thank You!

Posted in Articles, Combat Training, Defense, DIY, Equipment, Knowledge Management, Perimeter Security, Shelters, Tactics, Tools Tagged with: , , , , , , , , , , , , ,

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