Understanding Those Mysterious Black Cables on the Road

When you’re driving on the highway or a residential street, have you ever noticed those black cables carefully placed on the ground? They might not look like much, but they actually serve a very important purpose. Let’s find out more!

Easy Way to Understand Traffic Patterns

Those black cables are known as road tubes and they provide a simple and easy way for local transportation agencies to gather vital information about the traffic patterns in a particular area. You’ll often find them placed in unassuming areas, so they don’t cause any inconvenience to drivers.

How They Work

So how exactly do these road tubes work? Well, every time a vehicle’s tire hits one of these tubes, a burst of air is sent through the rubber tubing to an on-site counter that collects all the data. The tubing and counter are left in place for a specific period of time, allowing the data to be collected and analyzed.

But it’s not just about counting cars. The road tubes can also provide additional information such as peak traffic by analyzing the interval between air bursts. When used in pairs, they can even determine other details like vehicle class, speed, and direction.

Making Informed Decisions

All the data collected by these road tubes is extremely valuable to transportation agencies. It can help them determine if speed limits need to be changed or if signage needs to be updated. By having this information, they can make informed decisions to improve traffic flow and safety in a given area.


It’s fascinating to learn about these mysterious black cables on the road and the incredible amount of data they’re able to collect, all from a simple burst of air! Next time you see them, you’ll know just how important they are. Share this article with your friends if they didn’t know about them either!

To watch a video explaining the concept, click below: