What are the black tubes that run across Texas roads?

TEXAS (KXAN) -- Those traveling across Texas have probably seen -- and driven over -- a slew of black cords running across roadways. But what exactly are they, and how are they used?

The U.S. Department of Transportation's Federal Highway Administration (FHWA) calls them "pneumatic road tubes," an in-roadway sensor that can help detect and track vehicles traveling on roads. They're typically used as short-term traffic counts, with some models having the ability to gather data related...