Building Up: Does Anyone Do Risk Analysis?

I've often wondered why there is such a mania for building up to the heavens, when there are so many examples of cities that work (and work better) on a more human scale (see, eg, Richard Rogers (1997). Cities for a Small Planet. Faber and Faber, London, UK). High-rise buildings are inherently energy-inefficient, with their reliance on vertical transport and energy-intensive materials such as concrete, the need to lift heavy building materials to great heights and their inevitable reliance on air-conditioning because of the dangers of windows that actually open.

They are also socially-inefficient, because people rarely talk to each other, or interact in any way at all, in lifts. This lack of community has resulted in widespread demolition of 1960s public housing in many cities - a fate that could all-too-soon await more-recent high-rise apartment buildings.

But these concerns almost pale into insignificance compared to the potential consequences of structural or other failure. The stresses on a 40-storey building are many times those that a 5 or 10 storey building has to withstand - not just the weight but the wind stress and the effect of any shifting in the ground beneath.

It took the recent major cracking of a recently-constructed Sydney high-rise for someone to point out that it had been constructed on a reclaimed swamp and is only 300 metres from a still-existing swamp. 

NSW Urban Taskforce chief executive Chris Johnson has said that the problem with the Sydney high-rise would either be a 'fundamental error' in how the building was constructed or the ground it was built on.

It remains to be seen whether Sydney's Opal Tower can be made safe, but even if it is made structurally safe it will be a long time before residents actually feel safe. It is already being suggested that the problems in the building could trigger a fire sale, bringing financial as well as psychological losses (https://www.afr.com/personal-finance/opal-cracks-a-minefield-for-investors-20181226-h19h7b).


As one whose first sight of Australia was the stub-end of the then-recently-collapsed Westgate bridge in Melbourne looming out of the morning mist early one morning in July 1971 (and having many friends and former colleagues who are road and bridge engineers), I am perhaps more aware than most of the potential for, and consequences of, structural failure.

A key issue, in this and so many of the other instances of structural failure around the world, is the extent to which the risks of such failure were identified, managed and, where possible, removed. 

https://www.smh.com.au/national/nsw/huge-pressure-developers-cutting-costs-are-root-cause-of-defects-20181226-p50o97.html

So far, we have not been reported to have been faced with this sort of situation in Perth, but the existence of other, apparently unreported, major problems in other Sydney/Canberra high-rise buildings (https://www.smh.com.au/national/nsw/huge-pressure-developers-cutting-costs-are-root-cause-of-defects-20181226-p50o97.html) suggests we should not be complacent. In particular, where there are real identifiable risks, we should, at the very least, be wary of high rise development.

Which brings me to the Mill Point Area of South Perth. This is an area virtually surrounded by the Swan River and with a water table very close to the surface - indeed, recent experience indicates that groundwater here is also flowing rather than being a static water table. Most of the ground on which high-rises are proposed to be built is, effectively, saturated, which makes it very difficult to stabilise and compact. Deep piles down to bedrock, through saturated sands, increase the effective height of a building from stable foundations.

Of more general and fundamental concern is that Governments are increasingly giving effective control of development processes to the private sector, which has an obvious vested interest in maximising development yields and minimising construction (not necessarily maintenance or operational) costs. The process by which the Sydney Opal Tower was approved is not dissimilar to the Development Assessment Panels here in WA - to which the current state government is proposing to add a streamlined WA Planning Commission dominated by those same interests (http://ianrker-vincent.blogspot.com/2018/07/green-paper-modernising-western.html) and a Design Panel (for the purpose of approving 'development bonuses') also dominated by them (http://ianrker-vincent.blogspot.com/2018/12/wa-government-wants-more-conflicted.html).

https://www.theaustralian.com.au/business/property/opal-tower-residents-to-be-evacuated/news-story/ee8a7135eab1fc54996ef81ad05fc80c