Defensive realms: protecting cities from terrorism

How can we secure our cities from the threat of terrorism without destroying what makes them liveable?

December 2018

Artwork by Michelle Thompson

Words by Debika Ray

“Not long ago, a terrorist attack in a major city would typically involve highly trained groups from named organizations carrying out complex, large-scale operations designed to make maximum symbolic impact. Today, attacks are commonly low-tech and unpredictable”

Terrorism is continually evolving. As cities and organizations adapt, terrorists innovate — finding new ways to confound and circumvent measures of detection and defence. In recent years, this innovation has taken an unexpected turn: as security systems have become more advanced, attacks have been simplified and ambitions degraded. Not long ago, a terrorist attack in a major city would typically involve highly trained groups from named organizations carrying out complex, large-scale operations designed to make maximum symbolic impact. Today, attacks are commonly low-tech and unpredictable — carried out by lone wolves using improvised weapons and targeted at seemingly random groups of people in crowded locations of no obvious significance.

These tactics may change again. Advances in scientific research — from drone technology and smart cities to synthetic viruses and new chemical agents — open up new avenues of vulnerability and methods of attack. But if the purpose of terrorism is to create fear and uncertainty, one of the most potent tactics today is to simply grab a knife or jump into a van and kill indiscriminately: a method that’s cheap, easy, low risk, high impact and practically unpreventable.

“It’s pretty much DIY terrorism,” says Matt Brittle, head of security, risk and resilience at WSP in the UK. “It’s effective — you can do it without raising your profile — and you don’t need much skill, which makes it hard to know when the next one will crop up.”

In reality, the risk of being caught up in a terrorist attack is minuscule. US government figures show that in 2016 there were 25,621 fatalities worldwide from terrorist attacks, down 13% from the previous year. Terrorism accounted for just 0.06% of deaths overall, according to the Global Health Data Exchange, just over half as many as were caused by exposure to heat or cold. Arguably, if we react to such remote threats by over-militarizing our cities, we are helping terrorists to meet one of their main objectives: to create a climate of fear. In this complex landscape, governments, city planners and designers must strike a tricky balance between security and freedom, between a city that’s safe and vigilant and one that’s liveable, efficient and spontaneous.

“The term ‘resilience’ is now deeply embedded in the urban policy agenda at transnational organizations, governments, municipalities and think tanks. This indicates an acceptance that cities are continually subject to stresses, from natural disasters to political instability”

Mitigating impact

Cities’ responses to the terrorist threat reflect both their risk profile and their culture and politics. The tolerance for heavy-handed, visible security is, for example, lower in many European countries than in the US and the Middle East. But there has been a global shift in rhetoric around urban security in the years since the September 2001 attacks on New York, mirrored in the language around the development and management of cities. Specifically, the term “resilience” is now deeply embedded in the urban policy agenda at transnational organizations, governments, municipalities and think tanks. This indicates an acceptance that cities are continually subject to stresses, from natural disasters to political instability. Resilient cities can absorb and bounce back from those shocks.

“It’s almost a softer and more palatable version of emergency planning, a different way of trying to convey that governments have this under control,” says Jon Coaffee, professor in urban geography at the UK’s University of Warwick, who specializes in the impact of terrorism on cities. “It’s about anticipating what might happen and putting in place plans to mitigate the impact. Governments are moving away from the idea that you can defeat terrorism, so it’s a matter of ‘when’, rather than ‘if’ we are attacked. This necessitates that we prepare and constantly reappraise our capability to deal with a wide array of attack trajectories.” On a practical level this can entail physical responses by designers, engineers and planners to reduce disruption or casualties, as well as better urban management and more efficient, secure and adaptable systems for information sharing, medical intervention, law enforcement, utilities, transport and logistics.

While the term resilience has gained huge traction, it has also been criticized for its vagueness. In the context of terrorism, it shifts the focus away from the global political structures that create a fertile environment for terrorist activity, placing responsibility instead in the hands of individuals, technocrats and private organizations. The increasing privatization of public space in many major cities is one reason why that might be cause for worry — what is to stop private landowners with no democratic accountability from abusing their power to exclude and surveil?

"How our public spaces look and feel tells us a lot about us as a society. What does it say about us if all we can do is retrofit bollards?"

Jon Coaffee, University of Warwick

But this emphasis not on the agents of terrorism but on the results of their actions does empower designers to make cities safer. The definition of a “terrorist” is itself wide-ranging and politicized, points out Peter Richards, head of security risk management at WSP in the Middle East. “Terrorists seek to advance a political, religious or ideological cause, usually through acts of violence. But, to give one example, the French Resistance during the Second World War would have been classed as a terrorist group by the occupying government of the day. There will always be intent to carry out an attack, but we can limit the impact by reducing the vulnerability of the urban landscape to these acts of violence.”

In many ways, we haven’t yet adapted to the new reality of improvised attacks. This is reflected in the market for terrorism insurance, notes Henry Wilkinson, head of intelligence and analysis at the consultancy Risk Advisory. “Terrorism insurance is essentially property insurance. In the UK, for example, it’s very much conceptualized around the IRA threat: in other words, a large bomb that entails significant property damage.” Organizations, he says, need to be mindful of other consequences — for example, business interruption if there is an attack near their office, even though this may be harder to mitigate and quantify.

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Intelligent video analytics technology can flag up patterns such as loitering in real-time, or track suspects' routes through a city. Screenshots: Ipsotek

New threats, new solutions

The level and nature of the threat will continue to evolve as technologies such as drones become more accessible, says Sebastian Ihre, a specialist in security and social safety at WSP in Sweden, and one of the authors of a guide to hostile vehicle mitigation for Swedish municipalities. “Vehicles are probably going to remain the weapon of choice, because almost everybody knows how to drive a vehicle and it will take a long time to retrofit them with geofencing capability to actively restrict them from going into certain areas,” he says. “But in ten years, say, drones will be so easily attainable that they could become the next easiest weapon to use.”

So how does the language of resilience translate into the urban realm? With digital technology, equipment to enhance security has improved rapidly. Richards cites the relatively recent development of video analytics — security cameras with in-built intelligence that identify certain situations or behaviours through the use of algorithms. This has rapidly become the norm in surveillance, as such systems prove more effective than humans. “We are no longer reliant on people for reporting,” he says. “Algorithms can recognize behaviour such as loitering. For example, you can tell if someone is in an area for more than 20 minutes and if their movements are logical. Or a suspicious bag or object left in an airport or train station — if someone puts it down and moves away for two minutes, it will be recognized automatically and brought to the attention of the security operators by the camera system itself.”


Using virtual reality and simulation during the design process can also improve resilience, says Ihre. “You can run simulations of attack and emergency scenarios to see how the security design holds up, and better understand people’s behaviour too. Humans tend to be lazy by nature and they will cut corners, perhaps circumventing the security design and putting themselves in danger. Imitating humans and vehicles in the VR environment can identify vulnerabilities before it’s even built.”

As the threat has increased, so has the scope of design. “Before, you would look at protecting a stadium itself, but now it’s necessary to come outside the ground by about 200m to control those public streets and protect the crowd as it starts to build up,” says Brittle. “This is starting to be considered in a lot of places where there are large groups of people.”


As the location of attacks becomes less obvious and more random, there’s the emerging issue of “grey space”, he says. The bombing at Manchester Arena in May 2017 took place not in the arena itself but outside it. “The demise of a building probably stops 30cm outside for a property owner. The pavement doesn’t belong to you, it belongs to the council. But it’s on these pavements that attacks are occurring. It’s difficult to understand who is responsible for that space.”

Part of the problem is that taking control also means taking on liability, adds Ihre. “Most people understand that these grey spaces are the weak link, but at the same time, nobody wants to claim them as that’s generally connected to financial responsibility.”


What we’ve forgotten

There are, fortunately, some well-established approaches that designers can draw on, says Brittle. “People have been looking for years at new ways of doing these things, but it’s more about relearning what we knew before and have forgotten.” There are two concepts that emerged in the 1970s: defensible space theory by architect and city planner Oscar Newman, and crime prevention through environmental design by criminologist C Ray Jeffery. Both of these drew on the work of urbanist Jane Jacobs, who critiqued the top-down urban planning orthodoxy of 1950s New York and called for more mixed, vibrant and walkable cities and neighbourhoods.

Crime prevention through environmental design puts forward three tenets: natural access control, natural surveillance and territorial reinforcement, explains Brittle. “If you have a space where the use isn’t defined or reinforced, you tend to get people adopting it for whatever they want.” Take the front garden of a house: “A fence is territorial reinforcement — you’re saying, ‘This is my land, don’t sit here and drink a beer.’ Having a gate is also a level of natural access control, because somebody has to make a conscious decision to go through it.” Similarly, to reduce the threat of vehicle attacks, bollards or concrete barriers have become ubiquitous along pavements. “A lot of work is going into how to break up the straight run — to force a vehicle to slow down or swerve, so you have an early warning.”

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Then there’s natural surveillance: the idea that crime, or its effects, can be limited if it’s more visible. Vehicle attacks are less effective if there’s some element of warning — when a hijacked lorry was driven into crowds in central Stockholm last year, the crowd was alerted to the hazard early and people were able to get out of the way, Brittle points out; five people were killed, but it could have been many more. “The things that make people feel unsafe are not knowing the environment they are in, poor lighting and the inability to judge or avoid other people. If you can see things coming, that gives you opportunity to react. It’s the same principle as walking down narrow alleys — a nice wide street that’s well-lit gives us better situational awareness.”

Measures such as bollards have created a visible change in the public realm. In some ways, this sits uncomfortably with the spirit of the resilient city, with its implicit suggestion that the continuity of everyday life is as important as preventing shocks. “You could make the conceptual leap that resilience for some is about creating business-as-usual,” says Coaffee. “That feeds into economics: trying to keep the orderly flow of commerce going. But there is also a social argument. How our public spaces look and feel tells us a lot about us as a society. What does it say if all we can do is retrofit bollards into the public realm as a default response?”

model shows the new Rosendal district in Uppsala, Sweden
Security specialists can identify and resolve vulnerabilities at design stage by exploring virtual reality simulations. This model shows the new Rosendal district in Uppsala, Sweden. Visualization: WSP

"The things that make people feel unsafe are not knowing the environment they are in, poor lighting and the inability to judge or avoid other people"

Matt Brittle, WSP

Bollards were an obvious solution when the main targets were places such as financial centres, he says, which did not used to be overly concerned about accessibility and atmosphere. “But with a public square, it’s foolish to put in horrible militaristic security because that’s going to put people off going there as much as it’s going to reassure them it’s safe. We need solutions that are not so overtly brutalistic. Where possible, we should be designing things that are as unobtrusive as possible to try to balance the need for security with good design practices.” Citizens have often indicated that such overt security measures are an unwelcome presence, he adds — perhaps most colourfully in Melbourne and Milan, where ugly concrete blocks were decorated by local artists.

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Water features, hedges at knee level, concrete benches and public sculptures can all create obstacles and psychological barriers to attacks as well as natural surveillance, without a detrimental impact on the aesthetics of the public realm. The sculptural bronze bollards designed by Rogers Partners to secure New York’s financial district have been heralded as a more humanistic, friendly approach, providing a popular spot for workers to gather. In London, the ornamental, apparently stonework, balustrades in Whitehall have a steel core within, while the Emirates stadium features giant “Arsenal” letters at a critical access point (perhaps less subtly, there are also two huge cannons, part of the club’s insignia, that can withstand a seven-tonne lorry). “These ideas have been out there for many years,” says Coaffee, “but they aren’t being utilized as much as they could be, largely because they are expensive.”

Greenery is a popular and effective way to reduce the terrorist threat, says Brittle. “If you have substantial trees to break up the path of a vehicle, in many cases the attacker is likely to go somewhere else. That’s something people say they’d be happy to see more of.” But there can be unintended consequences. “Lining a road with trees might be good from a terrorism point of view, but bad from a crime prevention point of view because it creates shaded areas and potential hiding spots, and makes street lighting less effective. And when creating lanes with higher footfall, there’s an assumption that there’s more safety in groups. For some crimes that works, but for things like pickpocketing it doesn’t.”

concrete bollards were installed throughout central Melbourne
When concrete bollards were installed throughout central Melbourne to prevent hostile vehicle attacks, local artists responded by decorating them with bright fabrics and paint. Photo: Xinhua/Alamy Stock Photo

"Sometimes deviation is necessary. If front-line staff were to apply procedures in textbook form, a lot might not work and could just create more risk"

Kartikeya Tripathi, University College London

Another example is the barrier systems used to prevent cars driving into pedestrians. When pavements are crowded, people may spill out and walk in the gutter. “Then the bigger problem is cyclists running into them. Whatever you do, it creates another consideration. Everything is a balance — when it comes to design, we need to look at all of the threats and find the best solution. And if people don’t understand what it’s there for or how it benefits them, it’s pointless.”

It’s also true — for both cost and practical reasons — that there’s a limit to how much we can secure spaces themselves. “Every city or town has an element that is attractive to an attacker and you can’t protect every street,” says Brittle. “I think there is a realization that people have to do a little bit more. There are simple things: if you walk facing the traffic, you have a far better chance of getting out of the way.”

From The Possible, issue 04

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Ultimately, adds Richards, designing a resilient city is largely a matter of perception. “Terrorists look for the best return on investment — impact and publicity — so they will spend a lot of time and effort looking for the right target. They want soft targets that have some sort of ideological or political significance. If you have adopted the correct security posture and you have mitigation measures in place, you won’t eliminate the intent, but it might dissuade them from targeting you.”

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