Why did so many of South Australia’s electricity transmission towers collapse?

A high voltage transmission tower knocked down by strong winds in South Australia (Image: ElectraNet)

Australia’s media has now got on top of initial attempts by some politicians to try and blame Wednesday’s state-wide electricity black out in South Australia on renewable energy generation rather than the real cause, automated safety equipment shutting the system down after strong winds knocked down 22 high voltage transmission towers.

But there’s an electrical elephant in the room.

The big question that needs to be asked about South Australia’s electricity black out is: Why did so many transmission towers collapse in the storms?

Depending on where you were in the state, the wind speeds in the South Australian storms averaged 50kph to 65kph with gusts of up to 90kph to 115kph.

When Cyclone Yasi hit far north Queensland in early 2011 it was category 5 cyclone with wind gusts up to 285kph.

Cyclone Yasi was one of the most powerful cyclones ever recorded in Queensland. It took out street electricity poles and wires, damaged substations and blacked out 180,000 homes between Cairns and Townsville.

But, despite having 2 to 3 times stronger winds than the South Australian storms, Cyclone Yasi’s winds caused just 2 high voltage transmission towers to collapse.

Land slippage and erosion from cyclone related rain and flooding toppled 1 tower and undermined another 2 in southern Queensland, but Yasi’s super high winds only knocked down 2 towers in far north Queensland.

In April of 2015 severe storms in NSW blacked out 200,000 premises between Sydney and Newcastle and in the Hunter Valley.

Winds gusting up to 135kph up rooted trees, knocked down local street power lines and damaged electricity circuits and infrastructure, but the NSW high voltage transmission towers stood their ground.

What is wrong with South Australia’s transmission towers?

Here are few questions the Adelaide media should be putting to the power companies and the South Australian government.

Why did 22 South Australian high voltage transmission towers fall over in winds that weren’t as strong as the April 2015 NSW storms and were nowhere near as a strong Cyclone Yasi?

If you look at the photo above, from a lay-person’s glance, the concrete foundations of the tower seem short, small and under-weight to be anchoring a tower of that size and height.

Have South Australia’s electricity companies been skimping on the concrete they use in foundations or the thickness or amount of steel beams they use in constructing towers to reduce costs?

Are South Australia’s transmission towers designed or built differently to other states?

Are South Australia’s transmission towers built to world’s best practice?

It would also be interesting to know how many of the collapsed transmission towers were built since privatisation of South Australia’s electricity industry in 1999?