Terror, resilience and cities

An article in the Herald on Sunday by academic and so-called resilience expert Dr Bridgette Sullivan-Taylor really raised some questions for me:

You might be reading this in an Albany cafe or a Wellington hair salon. You might be in the Sylvia Park food court, a Riccarton outlet complex, a Westgate supermarket, waiting to bungy-jump off a bridge or even at the airport.

It has probably already occurred to you that, while doing these activities, you could be placing your life in the hands of terrorists.

Questions such as:

And also some more technical questions about how much we should be willing to pay for “insurance” against unlikely or unpredictable events. Dr Sullivan-Taylor continues:

Black swan extreme events — those that come as a surprise — have a major effect and are often inappropriately rationalised with the benefit of hindsight. The challenge is to be prepared for them…

Examples of this are the cyber threat to banks and other global systems from such things as Ed Snowden’s classified information leak from the National Security Agency over the past two years; Fonterra’s Chinese milk crisis that threatened our major primary market; and the Germanwings disaster a few weeks ago in which a suicidal pilot flew a plane with 150 people on it into the French Alps.

So basically, she strings together a small number of totally unrelated events into an argument that we’ve got to be prepared for the next low-probability event. In other words: the world’s a scary place, and you’ve got to be frightened wherever you go!

Dr Sullivan-Taylor argument seems to be that we have to be “resilient” to any possible threat, no matter how unlikely. That’s an interesting, if unrealistic, assumption that I want to revisit after looking at her recommendations for not getting victimised by terrorism at your local mall food court.

So how might this affect New Zealand consumers? Hardening or toughening soft targets could mean that if you are going to the mall, you might have your bag checked at the entrances, and there might be restrictions on how long you can stay in the carpark. Employees might require security passes, and purchases might be checked on leaving the mall.

If you’re going to the cinema, there could be more security screening, including bag-checking machines. You might see more CCTV or facial recognition software being used inside the mall and in carparks that are watching all your movements. Security or police staff might ask for proof of identification, carparks might be occasionally restricted directly under or on top of the mall, and we might see more information in the media informing customers about raised security threats at particular locations.

There are two problems with these recommendations.

The first is that there is almost no way that Dr Sullivan-Taylor’s recommendations would stand up to a cost-benefit analysis. For comparison, here’s a review of a recent paper on the costs and benefits of protecting airports from terrorist attack:

Mark Stewart and John Mueller are here to alert us about the security at our airports. They want to warn us that it is too good. Or, at least, there’s too much of it. Their new paper is titled “Cost-benefit analysis of airport security: Are airports too safe?” The answer, the authors say, is most likely yes…

Stewart and Mueller calculated the cost of traditional airport security measures and compared it against the risk of an airport attack, the cost of the damage an attack would cause (in lives and property), and the efficacy of particular security measures in preventing an attack. Their finding: “Many of the assessed security measures would only begin to be cost-effective if the current rate of attack at airports in the U.S., Europe, and the Asia-Pacific increases by a factor of 10-20.”

In other words, the benefit-cost ratio for measures to protect airports from attacks is in the range of 0.05 to 0.1. That’s shockingly low even by the standard set by the RoNS. Given that airports are more tempting and systemically important targets than shopping malls and tourist attractions, it’s likely that costly measures to secure everything will be even less worthwhile.

According to Mueller:

“What’s your chance of being killed by a terrorist if you’re American?” he says. “It’s now about one in 4 million per year. Maybe that’s enough, maybe that’s not enough. Some people might say we can save some money and make it one in 3.5 million. What I’m trying to do is just apply standard analytic techniques to the hazards of terrorism.”

If we assume that New Zealanders are equally at risk of terrorism as Americans – a pessimistic assumption, I hope – we’d expect one Kiwi to be killed by terrorism every year. We could probably save as many lives by upgrading half a dozen dangerous intersections or curves in the road as we could by totally preventing terrorism. In other words, the expected value of total “resilience” against terrorism is quite small, and dwarfed by other risks we face.

Professor Ramesh Thakur from the Australian National University made this point quite well in a Radio New Zealand report on the subject:

“Think of the attention that was given to the terrorist attack on Mumbai. Of course it was a serious incident. But, as I said, in terms of people who are killed on the roads in India and in India it is pedestrians and cyclists who are killed much more than people in the cars, or any other way you look at it, in terms of the real threats to people’s safety and security terrorism should rank way down in the scale.”

The second problem with Dr Sullivan-Taylor’s proposal is that the resulting cost, time, and hassle would dismember our urban life. Cities, by their very nature, concentrate people and bring them together in unpredictable ways. There have always been risks to doing so – consider the burden of disease in Victorian-era British cities or the impact of violent crime in mid-century American cities. Terrorism, or the perceived threat of terrorism, is just the latest high-profile risk.

People have chosen to accept a few risks from urban life because the benefits are far, far greater. Living around and interacting with other people gives you more choices about employment and more consumption options. It gives you better transport choices and more places to go. Frequent, incidental human contact makes us happier.

Putting a security checkpoint everywhere humans might gather together – from malls to the waterfront to buses to art galleries – will cost society much more than it will ever deliver in benefits. The added friction will make the economic life of our cities less efficient and productive and our social lives stultified and hesitant.

In short, Dr Sullivan-Taylor seems to be massively over-estimating the value of “resilience” and vastly under-estimating or ignoring the costs of her preferred solutions. We certainly shouldn’t ignore the risk of terrorism, but as with any other public policy issue, we need to address it in a cost-effective and considered way. Her sensationalised statements about the risk of terrorism at your neighbourhood cafe, and associated claims about the need to secure absolutely every public place, do not amount to a rational risk assessment.

Finally, while the Herald on Sunday never should have printed such an ill-considered take on a serious issue, it did raise the issue of how we value resilience against low-probability events in our cities and urban transport networks. How much should we pay for resilience? I’d like to say more on that topic, but it’ll have to wait for a future post…

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