Jane Embury looks at the threat of explosive attack
Architecture and urban planning have evolved over the centuries as countries and communities have responded to potential threat.
The earliest communities sought shelter and protection in caves. From ancient Egypt onwards, architecture has not only been about comfort and convenience but defensive capability.
Nowadays, we might not need city walls or castles with thick walls and battlements. But we do still need to feel safe.
At home, we have locks and smoke detectors. At work, we have fire alarms and clearly-marked emergency exits. The urban landscape is covered by security cameras.
Architecture has changed as well. For example, after the Great Fire of London, wattle and daub houses were banned in favour of non-flammable materials.
Nowadays, we have a plethora of fire and building regulations that are designed to ensure resilience in our built environment.
More subtle are the way that architecture has responded to threats, loosely termed as the Architecture of Fear.
This takes its name from a book of the same name edited by Nan Ellin, a US urban planning professor and published in 1997.
It was a series of essays on contemporary architecture, and how urban landscapes are shaped by our fears. Those fears, for example, are apparent in home design – locks, smoke detectors, security systems and gated communities.
Some of those fears are understandable. The fear of burglary or being in a building when it catches fire.
But the architecture of fear is also about recognising that some threats, while even more unlikely than a fire, can and do happen.
It’s why, some twenty years ago, we developed an advanced glazing system to counter the blast from a lorry bomb.
It isn’t a threat that’s uppermost in many architects’ minds, but it should be. As we wrote last week, Europol, the EU’s law enforcement agency, says that mental health is an important issue in relation to terrorism and violent extremism.
It believes that, in addition to already-radicalised Islamists, Covid-19 will have been another stress factor to potentially vulnerable individuals.
Europol makes the point that in 2020, there were 57 completed, failed and foiled terrorist attacks in the European Union. These were in Austria, Belgium, France, Germany, Italy and Spain.
They killed 21 people. In that year, some 450 people were arrested on suspicion of terrorism-related offences.
An important point, according to the data, is that all those attacks were carried out by individuals acting alone. Many will have been radicalised during lockdowns.
But it’s not just Islamist terrorism. Threats from right and left are also growing. In 2020, Italy alone recorded 24 left-wing and anarchist terrorist attacks.
The trouble with the architecture of fear is that we quickly forget what we should be fearful of. After all, there’s not been an explosive attack in the UK for a while now.
But, as Europol makes clear, it’s a threat that we should be thinking about, and incorporating protective measures into high value and public buildings.
Just in case we forget, the UK had 64 terrorist attacks in 2019, the highest in Europe, compared with seven in France and three in Germany.
In recent years, the Manchester Arena attack is a stark reminder of the carnage that terrorism can cause – particularly explosive attack. In that 2017 atrocity, 23 people died and over 1,000 were injured.
An explosion involves a rapid release of energy as light, heat, sound, and a shock wave. The shock wave may not last long but it travels at supersonic speed. It causes a huge increase in pressure followed by an equally large drop in pressure.
When it hits a hard surface, the wave is reflected, greatly amplifying the pressure. An acoustic wave will reflect with an amplification factor of two. A shock wave can reflect with an amplification factor of up to thirteen.
Designing in safety is all about determining the likely – or unlikely – threats that a building might face. The resulting threat assessment will then guide the design team.
The solution might not simply be about the building itself, but landscaping around it so that any explosive attack will be at a safer standoff distance.
But it’s also about glass, because modern architecture is all about glass – allowing light to flood in and connect a building with its exterior.
It’s also worth remembering that the majority of urban injuries when a building is attacked are caused by flying glass.
Research carried out by the Walter Reed Army Medical found that “blasts involving explosives inflict severe…injury, mostly as a result of secondary blast effects from glass [and other] debris.”
The Journal of Performance of Constructed Facilities says that “numerous injuries in explosions result directly and indirectly from window glass failure.”
We rigorously tested glass types and framing systems and found innovative ways to reduce profile widths, while maintaining the integrity of the glazed unit. In other words, that it could absorb the blast without breakage.
The objective of our research journey was to design an effective blast-resistant system that didn’t look like a blast-resistant system.
Since then, we’ve supplied to projects around the world – and not just for bomb or ballistic protection. For example, we supplied to a banking hub in Hong Kong, in a typhoon zone, to protect against high wind-loading pressures.
Sometimes, in the architecture of fear, all we have to worry about is fear itself. There again, erring on the side of caution is always the best option.
For further information on our bomb resistant glazing, check out our website page here where there are also videos of the test.