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Understand Defensive Architecture

This essay is a look at static infrastructure defense. This is not an encouragement to bypass or counter these defenses. Do not break local or federal laws. We recommend that you read this essay in conjunction with our ‘Counter Human Detection’ essay for a more complete understanding of the technologies involved in infrastructure defense.

Governments and private corporations have always had a vested interest in keeping their infrastructure and people protected. For many years this defense was satisfied by conventional security strategies - guard boxes, gate checkpoints, window security mesh, etc. In fact, in the pre-September-11 era, there are very few structures that can be considered to have defensive considerations baked into their architecture; the most recognisable exception to this being the 33 Thomas Street - AT&T Building, constructed through the early 1970s. 

Now that the Global War On Terror has come and gone it seems that almost every new construction has design considerations given to the defense of the structure. Even newly constructed schools have engineered areas for students to hide in, though this is hardly the extent of the new defensive architecture methods.


In order to build an appreciation of modern defensive infrastructure we will look at various design techniques including vehicle barricades, personnel canaling, and the reinforcing of windows and walls. We will then look into real world examples of national security and critical infrastructure architecture to understand how these techniques play together.

Definitions and Acronyms

Infrastructure - The underlying structure of a country and its economy, the fixed installations that it needs in order to function.

Mantraps - A small space with two or more doors where a person can be detained until they are identified or cleared for entry, often found in secure facilities.

Anti-Vehicle Barricades

Anti-vehicle barricades (AVB) form the first line of physical defense against any unauthorized or weaponized vehicles. While these barricades are typically employed as access denial to restricted areas, they can also be used to prevent a vehicle collision into a structure, or to mitigate damage caused by vehicle borne IEDs. It is not hard to think of examples of retractable or fixed bollards used to direct traffic or control access to parking lots, however, due to the simplicity of AVBs they have been retrofitted into many pieces of public infrastructure and are often hidden in plain sight.

When AVBs aren't built as bollards or gates, they typically take the form of simple emplacements like large rocks or reinforced concrete blocks. AVBs are usually built as close to the road as possible and accompanied by a buffer space of lawn or open area, this added space reduces the impact of vehicle borne IEDs, while also forcing any attacker to complete their final movement to the structure in exposed and open terrain. 

Windows and Walls

Windows are the weakest point of any building; it should come as no surprise that, when security is the most important design consideration, some architects do away with windows all-together. Reference the AT&T building from paragraph one. For many other architects, this almost ‘anti-human’ design choice is too much, and so they are forced to employ some level of reinforced/bulletproof glass. 

Glass is reinforced in roughly three stages:

First, laminate it. When glass is laminated (usually with polycarbonate sheets) it creates shatter proof glass. While shatter proof glass will still crack, it won't produce shards or debris and, depending on the layering and laminating, can maintain its shape even after extreme cracking has formed in the glass. Laminated security glass is typically accompanied by a tinted or mirror exterior laminate.

Second, make it thicker. This is a bit of a misnomer, while thicker glass is naturally stronger than thin glass, this is not why reinforced glass is thick. Thick glass is a byproduct of layering multiple laminated panels together. Due to the cost of this style of reinforcing, this thicker glass is typically only used on the ground floors of buildings.

Third, make it round. Circular cuts of glass are naturally stronger and more resistant to compression and shattering as their even edges mitigate pressure points where cracks can root.

In any building where porthole style security glass is used, it is safe to assume that the walls have already been greatly reinforced. Reinforced walls are almost always built from concrete due to its cost and strength under high temperatures and pressure. Reinforced concrete is built by embedding a steel substructure within the wall, newer constructions will also include steel micro fibers in the mixture to boost its strength. These reinforced walls are very resistant to drilling, blasts, and heating; considering most of these walls are more than two feet thick means that some of these structures will last far longer than the soil they are built on.

Personnel Canaling

Personnel canaling typically takes the form of funnelling people through chokepoints for the purpose of security screening. While most people are familiar with the turn style checkpoints at the entrances to subways and some sensitive locations, more secure facilities will employ more restrictive mantraps.

While explicit mantraps are rarer and typically exist in a central location inside of a facility instead of the main entrance, most secure facilities are designed in a way for the foyer to act as an impromptu mantrap. The foyers to many federal security/service buildings employ automatic doors controlled from a security desk and often employ protocols that would trap an attacker or saboteur in a single room as a means to mitigate the damage they could cause to the whole facility.

While mantraps and checkpoints work well inside of a facility, the main goal for most security teams is to identify threats before they even enter a building. To achieve this, high security locations will meticulously plan out pathways and approach directions to their facilities and employ landscaping and gardens to make breaking from these paths as awkward as possible. When these pathways are then combined with remote surveillance, it allows any security team the maximum amount of time to observe and identify potential threats before the threshold of the facility.

Case Study

This area of Canberra ACT is very unique. Within eyesight from the Australian Parliament House is several street blocks that house some very important buildings, including: 

The Department of the Prime Minister and Cabinet,

The Attorney-General’s Department,

The Office of National Intelligence, and

The Australian Federal Police Headquarters.

While each of these offices are locked up tighter than (insert joke here), the most important piece of infrastructure isn’t even marked on google maps. Sandwiched between Parliament House and the offices listed above is a small concrete building. Blackall St is a critically necessary communication hub servicing all the government offices in the area. This building is operated by Telstra, likely in conjunction with the Australian Signals Directorate to provide secure communication logistics as a part of the Ministerial Communications Network. 

Blackall St is a shining example of all the defensive Architecture techniques we have covered in this essay.

  1. From an information standpoint, this building is unlisted and unknown, with very little signage around the property and intentionally located in an unassuming and low traffic area. The only open source information on the property is a public feasibility study conducted during the planning for construction in 2006.

  1. Surrounding the building are small concrete cubes that act as basic AVBs, defending the site from any rogue or malicious vehicles. 

  1. The wall thickness seems to vary with a thinner 1 1/2 foot thick entrance area, and a thicker >2 foot main wall thickness, though this pales in comparison to the 5 foot thick reinforced roof, likely designed to counter a direct aerial bombardment. 

  1. With very few windows to the building, some of the only observation out of the site is via porthole windows on all 4 sides; we admittedly do not understand the purpose of these windows as they have a rather narrow field of view and are looking into an area that isn't particularly “strategic”, but for them to be included in this secure of a building there must have been a greater purpose that they are serving. 

  1. Finally, we can see a very unique entrance area, built as a circular attachment to the main building body. This area holds a security desk and several measures of access control (likely including a man trap, though it's hard to confirm this). 

With all of these design features combined, once the front entrance is sealed, it would be very difficult for even a conventional military to enter the site without leveling the building in the process. For any other clandestine group, these kinds of buildings can only be entered via a very complex and well planned deception strategy; as forcing entry is simply not feasible.

This essay is a look at static infrastructure defense. This is not an encouragement to bypass or counter these defenses. Do not break local or federal laws. We recommend that you read this essay in conjunction with our ‘Counter Human Detection’ essay for a more complete understanding of the technologies involved in infrastructure defense.


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