Next time you’re on the freeway or a residential street, pay close attention to the road. During your tour, you will most likely come across black cables that have been neatly laid on the ground. While they are entirely safe to drive over, what is their purpose? Road tubes are a simple and effective technique for local transportation organizations to collect critical traffic data.

They are often installed in unassuming locations to cause the least amount of interruption. When a vehicle’s tire contacts the tube, a burst of air is sent through the rubber tubing to the on-site counter, which records all of the data. After the tube and counter have been in place for a set period of time, the data is gathered and analyzed.

Not only does the tube count cars, but it can also predict peak traffic by measuring the time between air bursts. When the tubing is used in pairs, it can provide even more information, such as vehicle class, speed, and direction. This information can then be used whenever an agency wants to decide whether to adjust speed restrictions or update signage.