Crash Barriers

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Today, we’re going to get into the zone – the construction zone – on Engineering Works.

Everybody likes a smooth commute. Nobody likes to see traffic backing up for a construction zone. Even when construction crews are busy repairing or improving roads and streets, we still need to get the kids off to school and get to work ourselves. But it seems like everywhere we drive these days, we run into highway construction.

Well, not exactly. Engineers spend a lot of time and trouble making sure we don’t run into the construction. Portable concrete barriers are one way to keep traffic moving alongside the jackhammers and asphalt spreaders and protect construction workers from wayward vehicles.

For years, these concrete barriers were 32 inches high – about the height of your desk, at work. These barriers worked well for one-way traffic through the work zone. But when you added oncoming traffic, the number of crashes went up.

Here’s why. When the traffic is two-way, drivers pulling out of side roads and driveways couldn’t see over the 32-inch-high barriers. And at night, oncoming headlights were hard to see.

Engineers at the Texas Transportation Institute found that shorter concrete barriers could still do the job. They developed a low-profile design – only 20 inches tall. The shorter height makes oncoming and cross traffic easier to see. The result? Fewer construction zone crashes.

That’s the end of the road for today. See you on down the highway.

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Pass the popcorn

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Move over, multiplex cinema with 16 theaters. We’re going to get a sneak preview of what real wide-screen viewing is all about, today on Engineering Works!

Most of us never get to swim with whales or see the earth from the International Space Station. Seeing it through a high-tech movie called the IMAX may be the next best thing. It’s that real. But what make the IMAX so special?

IMAX technology’s beginnings came from popular multi-screen, multi-projector movies shown during the 1967 World’s Fair in Montreal, Canada. The first actual IMAX movie premiered during EXPO ‘70 in Osaka, Japan.

Let’s start with the screen. It’s big. Bigger than your house. In fact, you could set down two average houses in the middle of an I-MAX screen. But there’s more to it than that. Most movie screens are flat. The IMAX screen curves around toward you. Some IMAX theaters are shaped like domes. That huge curved image makes you feel like you’re in the action, not just looking at it. It’s so real that a few people get dizzy or seasick, just watching.

Add the sound. Special audio amplifiers and speakers put IMAX viewers in the middle of the action. Then there’s the film. Ordinary movies are projected from 35-millimeter film — the film in your camera. The film IMAX movies are projected from is 10 times bigger. No wonder the picture is bright and clear! In fact, it’s so big that the projector has to use a special vacuum-powered system to move the film.

So, next time you get the urge for wide-screen entertainment, think big. And pass the popcorn!

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Row, row, row your concrete boat

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Toss a chunk of concrete into the water and it sinks. So why are some engineering students building boats out of this stuff? We’ll go fishing for answers, today on Engineering Works!

The first boats were made of wood. That makes sense. Wood floats. Nobody thought it would work when folks started building ships out of iron plates. After all, iron is heavy. And it won’t float.

Engineers solved the problem of making iron ships float more than a hundred years ago. Think of it this way: if you float a block of wood in a bucket, the water level goes up, just a little. If you weigh the water that rose, it’ll weigh the same as the wood block. If you drop a chunk of iron into the bucket, it’ll sink and the water level will rise again. But this time, that extra water will weigh less than the iron.

Now, imagine that you’ve flattened that chunk of iron into really thin sheets and shaped them into a hollow block. That block takes up more space than the original chunk of iron, a lot more. This time, the water that rises in the bucket will weigh more than the iron, and the iron block will float. Shape the block like a boat and you’re good to go.

The students do the same thing, except they use concrete instead of iron. And instead of hollow blocks, they make long, graceful canoes. Students from across the United States and other countries get together every year for a competition to race the canoes they’ve built. They learn a lot: designing smooth hulls; finding the best mix to get light, strong concrete. … Hey, I’ve got a bite!

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