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On the critical list

Cover Story: After 9.11

Engineers are leading studies aimed at defending US infrastructure from attack. Consultant Bob Prieto tells Diarmaid Fleming how the findings have implications for the UK too.

The September 11 atrocities and subsequent anthrax attacks have led to an intensive review of infrastructure safety in the US. Much of this is being carried out or directed by engineers.

'There is increased focus on security, particularly in making our critical infrastructure secure. In October or November (last year) everything was critical, but since then people have realised that this cannot be so, ' says Parsons Brinckerhoff director Bob Prieto.

'Not every bridge or tunnel is critical to the economy of the US, but a number of them are. We are still at that stage of identifying those critical assets, and as we do have been focusing on making them more secure. Parallel studies are being carried out using different methodologies which will eventually converge.

'Surface transportation studies are looking at rail and road, such as major river crossings - bridges and tunnels - because they represent single point failure opportunities, ' says Prieto.

'But other studies are looking at major rail terminals because of the potential they present for weapons of mass destruction, chemical and biological.

'Evaluations are under way at federal and local levels to see if a test and training facility should be developed, maybe using an old stretch of tunnel. This would enable modelling of disaster scenarios to help develop response protocols and hopefully some technologies for detection and mitigation.

'If these move forward, hopefully there would be a good level of international interest, because London Underground for example would have the same problems, ' he says.

After the Tokyo metro gas attacks in 1995, Parsons Brinckerhoff was engaged to carry out disaster scenario studies for a similar attack at a major rail terminal in the US. The choice of targets was later to have a tragic irony.

Prieto say: 'We identified four rail terminals in the US which represented targets principally because of the volumes of people going through them - two of them were the World Trade Center and the Pentagon Station in Washington DC, both directly linked to the attacks on September 11.

'We created a hypothetical station from the four stations, enveloped what we saw, and ran a model for different scenarios, simulating the existing agency and city emergency response protocols.

'The outcome was that as many people would have been killed as on September 11, because current protocols for dealing with events in large transit stations are really for dealing with fire where the action is to evacuate.

'Many deaths were caused by secondary effects, people who were contaminated got out and affected other people at street level. Emergency rooms are not set up to handle biological and chemical contaminants - the normal protocol is to set up triage units outside hospitals.'

The studies highlighted the stark dilemmas that would face those responsible for managing infrastructure where large numbers of people congregate.

'The tendency in transit stations with fire or smoke is to ventilate - we identified that it's not a good idea to ventilate in biological or chemical attack, ' Prieto says.

'This raises real questions which are as yet unanswered: do we shut off the ventilation which will probably increase the fatality rate inside the station? Do you decide not to evacuate?

'These are not easy questions and are not for engineers to answer. But engineers can flag the questions. There is a new range of threats which we have to plan for - how these substances propagate in confined spaces and what the impact is at street level. London will have the same issues.'

Major security assessments of ports, reservoirs and water supplies in New York are under way, as well as top secret studies of cyber security.

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