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You won’t believe what those weird black tubes in the road are for

There are all kinds of unsolved mysteries in the world. The search for Bigfoot, Nessie the Loch Ness monster, aliens visiting Earth, to name a few.

We may never know the answers to those conundrums. It’s better to stick with more easily answered questions.

For example, what are those odd black tubes in the road used for? Fortunately, I can help you with this one. And no, it’s not a goofy elaborate watering system.

Have you ever wondered what those tubes are?

Have you ever been out for a drive and come across a black tube draped across the road? They’re pretty common actually, I’d be surprised if you’d never seen it.

They are actually called pneumatic road tubes. Most people think they’re used for counting cars, which they are, but they have many more functions than that.

They are used for short-term traffic counting, vehicle classification by axle count and spacing, planning, and research studies.

Some models gather data to calculate vehicle gaps, intersection stop delay, stop sign delay, saturation flow rate, spot speed as a function of vehicle class, and travel time when the counter is utilized in conjunction with a vehicle transmission sensor.

Check out the following video to see how it works:

According to the U.S. Department of Transportation, pneumatic road tube sensors send a burst of air pressure along a rubber tube when a vehicle’s tires pass over the tube. The pressure pulse closes an air switch, producing an electrical signal that is transmitted to a counter or analysis software. The pneumatic road tube sensor is portable, using lead-acid, gel, or other rechargeable batteries as a power source.

It’s a pretty cool system if you think about it. It can be set up permanently or temporary, so very flexible.

Now ya know what those crazy tubes are for. No more wondering.


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