Urban Security and Counterterrorism: An Approach to Proportionality

As cities and crowded areas increasingly become targets of terrorist plots and attacks, there is ample demand for risk assessment tools that consider proportional measures that reduce the threat, vulnerability, and possible impacts, whilst providing ‘security returns’ for those investments. There is a risk in this process of over- or under-fortifying places based on practitioners’ subjective biases, experiences, dead reckoning and conflicting agendas. Currently, risk assessments rely on qualitative tools that do not consider proportionality that removes these inherent biases. Critiquing well-known urban design strategies and national risk assessments, this article therefore seeks to develop a supplementary assessment tool – an equation for proportionality – that is more objective and is created to help practitioners make good choices, in particular on: (1) reducing the threat, (2) vulnerability, (3) impact, (4) accepting risk, and (5) measuring a security measure’s ability to deter, delay or stop an attack. It concludes that while no assessment is truly objective, the equation works to remove as much subjectivity as possible when assessing proportional urban security.