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Buildings withstand cyclone -

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Buildings withstand cyclone

Broadcast: 04/02/2011

Reporter: Peter McCutcheon

The red tape that saved lives. How tougher building codes helped north Queensland ride out the
storm of the century.


TRACY BOWDEN, PRESENTER: One death has now been attributed to Cyclone Yasi while another person is

But the human toll could have been a lot higher if it wasn't for strict building standards,
mandatory evacuations, and perhaps a bit of luck.

Preparing for extreme weather events has come a long way since Cyclone Tracy destroyed Darwin in

And with every disaster, emergency authorities learn important lessons about how to save lives,
even if it means more red tape for builders and developers.

Peter McCutcheon reports.

PETER MCCUTCHEON, REPORTER: This is a once in a generation storm. A cyclone so massive, so powerful
that it's force is being felt a thousand kilometres inland, in outback Australia.

But why was the human toll not as great as the destructive cyclones of the 1970s.

of better building standards and certainly much better scientific knowledge of what's happening.

We certainly are building for these contingencies.

DR JOHN HOLMES, WIND ENGINEER: If this event had happened early 1970s there would have been a huge
amount, a huge amount of damage and probably some deaths as well.

PETER MCCUTCHEON: The damage bill from Cyclone Yasi is expected to be around a billion dollars,
with extensive property damage and lost agricultural production.

Thousands of people have been traumatised, but without proper planning it could have been even

KEN GRANGER, DISASTER ANALYST: There's an old adage in emergency management that an aware community
is a prepared community.

They were aware, they were prepared and they acted. And that's what saved lives.

PETER MCCUTCHEON: The most destructive cyclone in the past 50 years is Tracy, which hit Darwin in
1974. But the cyclone that perhaps changed the way Australia prepared for extreme events hit
Townsville three years earlier, claiming several lives.

PETER SKINNER: Althea went through Townsville in the early 1970s, Wanda came through further south
and then Tracy. So we had a season of a number of years of high cyclone seasons.

PETER MCCUTCHEON: Associate Professor Peter Skinner is an architect with a research background in
the history of housing design. He says mandatory national building codes were introduced in 1975
and a cyclone testing centre was set up at James Cook University in Townsville to provide sound
scientific advice.

PETER SKINNER: There was a whole series of strategies that can provide the brace and force to
resist the wind force. But the first step is to work out, calculate, what the likely wind-force is
and to look at your building and see how you can provide the opposing forces.

And that's been happening since 1975.

JOHN HOLMES: Basically the post-1980 housing has stood up pretty well it looks like.

PETER MCCUTCHEON: Dr John Holmes is an engineer who provides scientific advice on wind loads to the
Australian Building Code Board. He has another theory why many buildings survived Yasi. He suspects
the gusts were nowhere near the 300 kilometres an hour predicted by the Weather Bureau.

JOHN HOLMES: They were calling the event 300 kilometres an hour whereas their own anemometer on the
reefs were saying something a lot less, more like 200 kilometres.

They're both very high wind speeds, let's face it. I suppose 200 kilometres an hour is the speed of
a Ferrari or something whereas 300 kilometres is a Formula One. But what that does to the force is
it kind of doubles the forces, going from 200 to 300. So, you know, it does make a hell of a
difference and the buildings that are designed for 200 are quite likely to come apart under 300.

PETER MCCUTCHEON: Nonetheless Yasi was a deadly storm and disaster analyst, Ken Granger, says State
and Local government authorities did an excellent job raising community awareness.

He says senior emergency service staff visited the Hurricane Katrina disaster area in the US and
learned some valuable lessons.

KEN GRANGER: The other thing that I think was quite unusual, or new, was the fact that they had
decided to take pre-emptive action. They had a warning of a potential event, an event that was
going to be very, very dangerous, so they started to act very, very soon.

PETER MCCUTCHEON: Another factor which helped lessen the impact of Cyclone Yasi was luck.

It hit on a lowish tide, reducing storm surge, well away from the two regional cities of Townsville
and Cairns.

KEN GRANGER: They're so unpredictable, these beasties. They really are. And more often than not
there's a lot of local terrain effect that can determine whether a building's going to get
flattened or not.

The bullseye hit with a big storm tide on the top of high-tide, the modelling's been done. We know
what it will do in Cairns. And that's why they moved people out of the low-lying areas when they
did. It was good on them.

PETER MCCUTCHEON: It's been 40 years since Tropical Cyclone Althea hit Townsville. A bullseye hit
on a low-tide was still catastrophic.

But emergency authorities, builders and meteorologists have learned a lot since then. And there are
still more lessons to be learnt, with talk now of strengthening the cyclone building code and even
moving it further south, from just below Bundaberg, to take in Queensland's Sunshine Coast.

JOHN HOLMES: Something that's on the agenda I think to look at at the moment. I think a lot of the
computer models are predicting cyclones will hit something like the north of the Sunshine Coast,
maybe Noosa and Caboolture, and those kind of places.

We may need to extend the cyclone region further south because buildings in that area are
definitely not as built for this cyclonic resistance.

PETER SKINNER: Certainly the ones that have been built since 1975, you've got the engineering
results to demonstrate those buildings are capable of resisting the design forces. The big question
now is whether those design forces are appropriate.