I'm guessing that everyone who drives has had the experience of being on a road that you drive regularly, only to discover one or two black tubes (that weren't there before) stretching across the street.

The tubes are obviously too small to act like a speed bump and slow you down, and there's nothing sharp on them that will rapidly deflate your tires like the StopSticks that law enforcement will sometimes use to end a car chase...so what are they there for?

International Civil Engineering Community, Facebook
International Civil Engineering Community, Facebook
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If You Are Of A Certain Age, You Might Remember That "Back In The Day" Full-Service Gas Stations Had Them To Alert Employees That A Customer Had Pulled Up To The Pump

I'm guessing that if you're under the age of forty, you have little to no memory of the black rubber tube that stretched across where you pull up to the gas pump, and even less memory of full-service gas stations, or gas station attendants who wore a uniform:

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Regular or Ethel, ma'am? (Getty Images)
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This dude was ready to handle whatever your car needed, and sell you a map.

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"Can I smoke here?" "Why sure sir, it's the 1940s!" (Getty Images)
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As these two show, we need more hats and uniforms in today's world.

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When we're done, show me how to fold this thing, willya? (Getty Images)
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The Black Rubber Tubes You See On The Street Are Called "Pneumatic Road Tubes," And They're For Governmental Use, Not For Drivers

According to Jalopnik, the technology they use is simple. Every time a vehicle’s tires roll over the tube, it sends a burst of air that triggers a switch that produces an electrical signal which is recorded by a counter.

A single pneumatic road tube is most commonly used to simply count the number of cars on the road, as well as time the gaps between individual vehicles.

If two pneumatic road tubes are set up spaced slightly apart, the counter can track the number of axles a vehicle has to better determine each individual vehicle’s class, the direction of traffic and the speed at which vehicles are moving.

Here's a good explainer for the process:

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LOOK: See how much gasoline cost the year you started driving

To find out more about how has the price of gas changed throughout the years, Stacker ran the numbers on the cost of a gallon of gasoline for each of the last 84 years. Using data from the Bureau of Labor Statistics (released in April 2020), we analyzed the average price for a gallon of unleaded regular gasoline from 1976 to 2020 along with the Consumer Price Index (CPI) for unleaded regular gasoline from 1937 to 1976, including the absolute and inflation-adjusted prices for each year.

Read on to explore the cost of gas over time and rediscover just how much a gallon was when you first started driving.

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