The London Underground is one of the world’s oldest public transportation systems. Until recently, it was also an organizational mess. Duties for repairs and maintenance were spread among a host of separate divisions that didn’t communicate with each other, leading to disasters like a 1987 fire in Kings Cross station that killed 31 people. Although the Underground has become much more organized since 1987, they were looking for a way to make repairs even easier. That’s where the Internet of things (or as the rest of us say, smart devices) come in.

Transport for London, the name of the organization that runs the Underground, has been working with contractors to install network-enabled sensors in their CCTV (security camera) systems, escalators, PA loudspeakers, air conditioning systems, and subway tunnels that allow central systems to manage, monitor, and automate individual tasks. The smart devices, which run on a Microsoft Azure Intelligent Systems Services backend, were installed in the Underground by telecom firm Telent and sensors developer CGI.

According to a blog post by Microsoft’s Barb Edson, Transport for London uses a central control center to monitor and aggregate sensor data from across the tube system, as shown in the video below.

Edson added in a statement to Co.Labs that the sensors are used for tasks like identifying when escalators vibrate oddly, which leads to pointing out potential mechanical issues before they actually occur. Metrics like power and temperature are recorded, along with additional information recorded by the sensors.

Transport for London’s central control centers use the aggregated sensor data to deploy maintenance teams, track equipment problems, and monitor goings-on in the massive, sprawling transportation system. Telent’s Steve Pears said in a promotional video for the project that “We wanted to help rail systems like the London Underground modernize the systems that monitor it’s critical assets–everything from escalators to lifts to HVAC control systems to CCTV and communication networks.” The new smart system creates a computerized and centralized replacement for a public transportation system that used notebooks and pens in many cases.

This means cost savings for Transport for London; Microsoft expects that the new system will make running their rail support network 30% cheaper while also improving customer service levels. The smart devices will primarily be used to automate manual processes, detect equipment issues in real time before they cause service problems, and for infrastructure planning.

For Microsoft, Telent, and CGI, this also means a valuable profit opportunity. Sensors on connected devices generate massive amounts of data when aggregated; Scott Gnau, the CEO of Teradata (a Microsoft partner) told Fast Company several months ago, during a separate interview, that a single functioning jet engine can generate up to terabytes of data per hour. Large, decentralized infrastructure projects like the London Underground are massive moneymaking opportunities for companies serving the smart device market.