system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do GPS apps such as Maps or Waze know the new formation of roads after construction?
gpt
It first important to understand how Google Maps gets all if it's data. Some of it's data is pre-programmed into their systems. This is usually used as initial data, especially for testing. Google provides many more features, however. They also show traffic and other information for your daily traveler.

A few years back, Google acquired Waze and they use data from the Waze app to enhance Google maps. Waze is backed by a community of users who report cops, traffic, accidents, etc. But Google also injects tracking into their software. Google can access the speed of your car by checking it's locations at two different points and dividing it by the time between those two points. If the speed limit on a road is 50 mph, but every car on the road using Google maps is moving only 10 mph, then there is obviously traffic.

Using the same technique Google will track a cars movement. If a car is going off course, then Google will ignore the data, but still store it for later use. If 50 cars go off course, Google's map algorithm will detect this as an unknown road. Google will run several Artificial intelligence tasks to determine what is going on and will adjust their data accordingly.