Train kept a rollin'

North America's largest railroad, Union Pacific, uses thousands of sensors to keep trains running smoothly, detecting problems and flaws in an effort to prevent derailments.

From refrigerators to freight trains, CNBC's "Rise of the Machines" shows you how a new generation of connected machines can now speak to us, and each other. "Rise of the Machines" premieres Wednesday, Sept. 18 at 9 pm ET/PT.