Traffic cameras

A traffic camera is a video camera which observes vehicular traffic on a road. Typically, these are put along major roads such as highways, freeways, motorways, autoroutes and expressways, as well as arterial roads, and are connected with optical fibers buried alongside or even under the road, with electrical power either provided by mains power in urban areas, or via solar panels or another alternate power source which provides consistent imagery without the threat of a power outage during inclement conditions.

A monitoring center receives the live video in real time, and serves as a dispatcher if there is a traffic collision or some other disruptive incident or road safety issue.

Traffic cameras are a major part of most intelligent transportation systems. They are especially valuable in tunnels, where safety equipment can be activated remotely based upon information provided by the cameras and other sensors. On surface roads, they are typically mounted on high poles or masts, sometimes along with street lights. On arterial roads, they are often mounted on traffic light poles at intersections, where problems are most likely to occur. In remote areas without easy reach of the main electrical grid, they are usually powered by another means such as solar power, which also provides a backup source to urban camera infrastructure.

...
Wikipedia