I love hidden technology. Now, I don't mean weird Illuminati perpetual motion machines; instead, I mean the kind of technology we see every day but aren't aware of. A really great example of this is road barriers.
Road barriers definitely aren't sexy, but they're important. They save a ton of lives every year, and though they look like boring concrete walls or dirty corrugated metal bolted to splintery wood, there is a ton of technology that goes into the design and implementation of road barriers.
That's why I found this YouTube video from user Andrew Lam so fascinating. In it, he breaks down the different kinds of barriers and their pros and cons relative to one another. He talks about concepts like clear zones and crash costs. He even gets into different types of crash attenuators -- my personal favorite is the water- or sand-filled barrels invented by racing driver John Fitch, aka Fitch Barriers -- and how they work.
It's not a short video at 15 minutes, but it's worth your time if you're interested in infrastructure and a better understanding of the way our roads work. I know I'll never look at a guard rail attenuator the same way ever again.