You may have encountered black cables stretched across the road, but why are they there?

What Are Those Black Cables?

Those black tubes are called pneumatic road tubes. Transportation departments use them to collect traffic data. When a vehicle’s tires pass over the tube, the air pressure inside it changes. That burst of air triggers a counter device attached to the side of the road, recording valuable information.

What Information Do They Collect?

These tubes help traffic engineers gather data such as:

• Vehicle count (how many cars pass through)
• Vehicle speed
• Traffic patterns and peak hours
• Vehicle classification (in some cases, distinguishing cars from trucks)

When two tubes are placed a short distance apart, the system can measure the time it takes for a vehicle to travel between them — allowing accurate speed calculations.