What are Those Two Black Cables on Washington Roads?

What are Those Two Black Cables on Washington Roads?

Have you seen two black cables lying across a road in Washington? I’ve recently seen this in a couple of locations around my hometown. In both cases, they are placed with a small spacing between the two black wires, or cables.

What are they? 

What is it measuring? 

Are they trying to catch you speeding?

Yes and no on the speeding part.

The two black cables are pneumatic road tubes that gather information for the city or county.

'One pneumatic tube can track the number of cars driving over a road in any given span of time. By measuring the time that passes between air bursts, officials can determine which time of day has the most traffic congestion.

Two pneumatic tubes installed slightly apart from each other paint an even broader picture. Using this method, government agencies can gauge the class, speed, and direction of each vehicle that passes through' - mentalfloss.com

The information from the pneumatic tubes tells city or county planners: 

* The number of vehicles that pass over them

* The size of the vehicle

* The length (is it a passenger vehicle or an 18-wheeler semi?)

* What’s the weight?

* How fast speed are the vehicles traveling on that stretch of road?

Sometimes the cables are installed for a short time, (24 hours), while others are left there on the road for days or even weeks.

Information that is collected can help state or city governments better improve roadways.

Here is a video explaining how road planners use the info:

INFO: Mentalfloss.com, Nick Moore (YouTube Channel)