You've Been Riding Escalators All Wrong
Escalators are, if you think about it, terrifying.
We're used to them because they exist in almost every public place. But take a closer look at these hellish contraptions and you'll notice the sharp-toothed steps, the slice as each one disappears, and the relentless push that beats to the drum of 'keep up oo suffer the consequences'.
In short, they don't look like a fun place to have an accident -- as Ten's Natarsha Belling found out to her detriment a few months ago.
Most recently, 24 people were injured when an escalator in Rome collapsed. The current theory from local media is that something went wrong when soccer fans who had crowded the escalator started jumping up and down.
It's too early to tell what exactly happened, but watching the footage, Paul Briozzo from the School of Aerospace, Mechanical and Mechatronic Engineering at the University of Sydney told ten daily it looked exactly like a problem he'd encountered before in an inclined elevator.
The footage shows the crowded escalator moving extremely fast, with people piling up dangerously down the end.
"I suspect that what happened here was that an excessive load has caused a shaft failure," he said.
What that means is: the crowded escalator had already increased the static load, i.e. the weight the escalator was carrying. When people began jumping up and down it increased that load, bringing it to something the escalator was probably never designed for.
And when you have a shaft failure in an escalator travelling downwards, the motor that's trying to maintain a constant speed can no longer do so.
"It's like when you're driving a car and you suddenly put it into neutral," he explained.
It's why in the footage we see the people on the escalator travelling downwards so quickly, compared with the people on the left who are travelling at a normal rate.
"It's like falling through space," Briozzo told ten daily. "What we're seeing is a visual representation of potential energy being converted to kinetic energy."
In other words: gravity is doing its work.
Although the Rome incident is awful -- one person is facing a possible foot amputation -- it's nothing quite like the horrific incident in China a few years ago, where a mother was 'sucked down' into the escalator after a metal panel collapsed.
Her last act was to throw her young son to safety.
"Escalators are a very specialised area," Briozzo said. "The China incident was a completely difficult issue."
But incidents like that are part of the reason he's careful about how he rides escalators, and why he's teaching his son to do the same.
"I'm teaching my son: when you stand on the escalator, always put your feet on the edges a bit," he said.
"Don't stand in the middle, because in the middle you've got maximum stress."
He's also inclined to walk, rather than stand, on escalators, not just for timely convenience but to spread the load.
The thing is, in reality, escalators are extremely safe. As Briozzo pointed out, riding on one is far safer than getting in your car to go home.
But when you have machines that get used over and over, where a point of stress turns into a crack and a brake fails, in these very rare instances you can get "catastrophic failure".
And that, he said, can be very hard to check for.
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Lead image: Natarsha Belling / Instagram; Twitter.