Scientists have designed a “skin” that senses when concrete structures are damaged

Image: Bittbox via Flickr, reproduced under creative commons.

Concrete is pretty great, isn’t it? It’s strong, it’s cheap, it’s easy to use. Let’s hear it for concrete!

On the downside, though, it’s also prone to cracking – if there are swift changes in temperature, for example, or if it’s bearing too much weight. Cracks in concrete structure are annoying at the best of times, but if said structure is holding, say, nuclear waste, they can also be disastrous.

So a team of scientists from North Carolina State University and the University of Eastern Finland have developed plans for a “skin” that would flag up cracks or damage to the concrete’s surface. Their idea involves installing electrodes at the edges of a structure, then applying electrically conductive copper paint across the concrete. The electrodes would emit a constant, low-level current across the surface of the painted “skin”, monitored by a computer. If the surface was weakened, cracked or damaged, the paint would become less conductive, and the computer would sense a change in the signal. You can even analyse the data to produce a map of the damage.

Here’s a cracked piece of concrete, alongside a computer rendering of the damage:

Image: Aku Seppänen.

So far, the researchers have only tried the method out on small, 1m long pieces of concrete, but they’re hoping to test on bigger areas. Dr Mohammad Pour Ghaz, one of the paper’s co-authors, said the team were keen to show the method could work on “real-world structures”.

 
 
 
 

“It's not a transport mode – or even a technology”: Public authorities should stop wasting money on hyperloop

This may well never happen. Image: Hyperloop Transportation Technology.

Remember the Hyperloop? In August 2013, superstar businessman and outer space-botherer Elon Musk published his concept for an entirely new transport system. Levitated pods whooshing round aluminium tubes at 1,220km/h would deliver a “massive return” by being far faster, cheaper, safer and just god-damn better-er than existing public transport.

The tech media, already keen Musk followers owing to his Tesla electric car business and his SpaceX commercial rocket venture, lapped it all up. Since then, clickbait headline after clickbait headline has breathlessly told us that the Hyperloop is “really happening“, “officially” being built by Musk’s company SpaceX (despite its insistence that it’s not doing any such thing), and wait for it, “kinda serious“. Take that, high speed rail! Naysayers like your humble correspondent, who took a more sceptical view back in 2013, were chastised for failing to recognise Musk’s brilliant visionary qualities.

Since then, the Hyperloop has not got much closer to leaving Elon Musk’s sketch pad and becoming a commercial reality. Of the two main companies trying to develop the idea, the more sober contender, Hyperloop One, has managed to reach the stage where it launched a metal sled along a track at less than one-fifth the promised Hyperloop speed. It still has no idea how to safely transport passengers in a sealed pod inside a tube.

The other firm, Hyperloop Transportation Technologies, seems to be mainly preoccupied nowadays with “augmented reality windows“. These sound nice, but won’t help achieve those near-supersonic speeds.

If that were all that was happening, there might not be any cause for concern. But in the last few months, an alarming development has started to emerge: public bodies have started to invest time and money in the Hyperloop.

French state rail company SNCF has found the money to buy shares in Hyperloop One; this is the same SNCF which posted record losses this year, and is struggling to find the cash to keep its regional train services going. A Russian sovereign wealth fund has also invested, apparently with the blessing of President Vladimir Putin. The Slovakian government has also bought into the idea to link up its cities. Deutsche Bahn is working with the rival Hyperloop developer on its fancy windows.


And there’s the worry. As long as the Hyperloop remains the plaything of entrepreneurs and venture capitalists, it need not trouble the serious business of delivering transport infrastructure for cities. But as soon as public authorities and policymakers start to invest in this idea – either financially or politically – we should all be scared.

Because the Hyperloop is not, contrary to what its developers claim, a transport mode. It’s not a technology, either. It is a concept.

Musk called it right back in 2013, when he called his 57-page pipe dream an “alpha concept”. For all the lab work, fundraising and bubbly news stories of the past three years, there is still no actual settled design for the Hyperloop system. There’s not even any conclusive proof that is even technically feasible.

Nor is there any proof that it’s affordable. Hyperloop cost estimates to date have failed to price in realistic costs for land acquisition: they are guilty of treating the Hyperloop like a mass-produced widget that can be churned out ultra-cheap on a production line. In practice, infrastructure projects are notoriously resistant to this lean and mean approach.

To a non-geek, infrastructure is boring, and for a very good reason. Major projects like Crossrail are expensive, complicated to deliver and require several years of studies, consultations, and legislative and regulatory approval to get done properly. As a public authority, you can only justify spending that kind of time and money if you’re certain that the thing is so boringly conventional, so tried and tested and trusted, that will work at the end of it all.

Dream on, lads: a proposed US hyperloop network. Image: Hyperloop Transportation Technology.

It’s also, incidentally, the only way you can convince private finance to back the project, as governments around the world are trying to get them to do more and more. Venture capital’s all very well for the exciting bit in the laboratory, but to build an infrastructure project, you need cheaper, long-term finance, which looks for low-risk, technologically safe schemes.

We as a planet face an infrastructure gap. We just can’t sustain economic growth without improving our infrastructure. Any government that takes the Hyperloop hype that “this is happening now” at face value risks wasting precious resources on an idea that may never become reality – all the while, not spending those resources on technologies, like high-speed rail, that exist and deliver real benefits.

So by all means, let the Hyperloopies have their fun. Let them raise cash from private backers and continue to shoot bits of metal on rails in the Nevada desert. But please, for all our sakes, don’t think it can replace boring old trains and buses just yet.

René Lavanchy is a recovering infrastructure finance journalist and tweets at @InfraPunk.

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