For Arup director Peter Bressington, the 11 September terrorist attacks had a huge impact not only on his work in fire strategies and evacuation, but also on people's awareness of safety issues and their perception of buildings
It must be hard staying upbeat when your job is to anticipate biochemical hazards, bombs, terrorist attacks and their effects on buildings and the users within them. But Arup director Peter Bressington manages to do just that.
'You can't let it get you down, ' he says.
'You're dealing with a hazard and something which is a negative, but what you can't do is let it get too close. If I personally was subjected to something, or knew someone close that had an experience, then I'm not sure how I'd feel about it, but at the moment I feel it's a design issue and it's about a measure which makes things better. I get more depressed about what's happening in Iraq, to be honest.'
Bristol-born Bressington heads Arup Fire, coordinating the work of some 100 fire engineers across Europe, Australia, Asia and Europe. He describes the company's approach as strategic, design-based, but 'non-prescriptive'.
'We tend to look at fire from first principles, ' he says. 'If an architect comes to us with an unusual building or feature, like an atrium, then we look at that and try to come up with an alternative way of providing an appropriate level of fire safety.'
That is because, he explains, any building code you can look at is prescriptive in that it gives you such things as escape distances and fire resistances.
'What we want to do is understand what lies behind those prescriptive codes and meet those goals in a different way. But the big difference since 9/11 is that it's actually focused far more on the performance side and about how people are likely to react in a fire situation. Since then, we've had to understand far more about extreme events, about fires which may not be associated with a particular occupancy - aviation fuel in an office for instance.'
Bressington joined Arup 13 years ago from a contracting background, including project management work on power stations. 'I was hugely surprised when I joined Arup that you could have an idea and have quite a lot of freedom to develop it, ' he says.
Then, fire engineers were part of R&D, so they were giving ad hoc advice as experts, for the firm. That changed in the 1990s when Arup found it was doing more external commissions, though it is still half and half. Bressington was allowed to widen the role into structures rather than purely systems, setting up his division in Hong Kong and handling the steep learning curve that resulted. Today, he is working there again - Sars virus-allowing - on a new ferry terminal building.
But it is events that are stretching the traditional safety levels of buildings. A developer intending to build, for example, a 50-storey building could be advised to focus on wider staircases or concrete cores rather than dry-lined cores to give extra robustness, or ductile floor connections to mitigate against progressive collapse.
'You can do all those sorts of things but that's what I would call hard issues, the design issues, ' says Bressington. 'The softer issues are rather more difficult to deal with' These are mostly people and businessrelated, including the ways occupants perceive the building in terms of safety.
'Now that's something again that is very new. If you spoke to any occupant anywhere prior to 9/11 and said 'what is your priority in terms of working here?', it would be the air-conditioning, the lighting, restaurant facilities, the comfort of the chairs. I'm guessing, but I'd have thought safety would not be very high on that list.'
There has been, he feels, an education process. 'The whole awareness issue is very much to the forefront, and particularly so when it comes to evacuation.'
One unconventional approach to evacuation in the event of a fire or other disaster is to use lifts. 'There's no reason why they shouldn't work unless a building has been impacted, and it should improve evacuation times by 40 per cent, ' he says.
Plus, up to 15 per cent of people in any building have a permanent disability or other problem that would prevent a staircase exit - a problem for others trying to leave the building, too. Lift shafts, of course, need to be made more robust and more able to deal with smoke. 'But to just say you can't use lifts in any circumstances because stairs are safe we think that's not necessarily the case.
That's one of the big design issues.'
When the 11 September attacks happened, Bressington's reaction, like many, was of shock. But this was followed by a concern that there would be a knee-jerk reaction against performance design.
'And that happened, ' he says. 'Some authorities were saying, 'the first thing you've got to do is put a four-hour fire resistance on a structure', or 'you need to have wider stairs', in a very prescriptive sense. But it's actually totally changed. There have been more opportunities to look at some of the more innovative ways of dealing with structural collapse and, because of the problems of insurance, even insurers now have a thirst for information.'
Unusual methods of escape have been looked at, such as parachutes, abseiling lines and the like. But tenants need to access them easily, they need to be well trained, and there are issues about visitors - it being 'a little bit dishonest' to give them something with a very small chance of success. Bressington believes these can also be a distraction, problematic in the insurance world, and send out the wrong message. The positives outweigh the negatives, but high-level linkages of buildings might be one answer.
It is not only tall buildings that are at risk from terrorist attacks. Bressington, who disseminates his knowledge voluntarily through committees and professional institute work, knows a lot of people who won't go on the Tube. He does so himself, saying it is a risk he chooses to accept, even if a disaster there is perhaps more unpalatable than above ground. But he believes people's perceptions may change over time.
'It may be a bomb, it may be biochem - there are all manner of threats, ' he says. 'We all accept them as risks, but it's more comforting with an understanding of what might happen.'