I was using GPS Google directions to drive and was surprised to see that I was redirected where the road has been closed and same with the road that had become bad and unmotorable.
I wonder what mechanism this uses.

Your answer lies in your mobile. Android mobile is more of a useful gadget to Google than it is to you. As you must be already knowing that Android keeps track of your location history. That history is uploaded to the Google servers which is used by Google to give you directions and other services.

Say for example 1000 people with android devices used to take that path every day. But all of a sudden it went down to ZERO. Now Google's algorithm will track that change and suggest you not to take that path and will suggest you a different path.

This is how Google is able to give you near real time traffic updates. So if you travel through a path, Google will use your data i.e the distance, path, time etc to tell near real time traffic on that path to others.

This is not the only source that Google uses. It also has various other sources and methods to collect the data.

Google has has various innovative softwares where it uses the whole world to solve its own problems

Now where does it gets the data Google has certain partners by the help of which it maintains the database of Google Maps . Since it has to be real time so it is very important to cross verify that data and then get it published . So Google takes help from -

Map partners: Google has partnered with various data sources with the help of Base map partner program and a large number of agencies submit data to GOogle .
Street view: Based on the GPS coordinates of vehicles Google cover the surface it’s street view images.
Satellites: Google map also add satellite view with the collaboration with Google earth.
Location services: Google access the location data collected by your smartphone.
Google Map makers: it is an another way which allow anyone to contribute their local knowledge top google maps. ( as mentioned in detail by )
Local Guides : As well as its army of editors, Google also has millions of so-called local guides . When you’re in Google Maps, go to My Contributions and you can search for different places in your area. By leaving a review, answering a few questions, and submitting a photo, you can contribute to this additional layer of data.
This is without doubt a huge task. That’s why Google has teams around the world dedicated to keeping things up to date in every country in which it operates.

Beginning in 2009, Google turned to crowd-sourcing to improve the accuracy of its traffic predictions.
Crowd-sourcing This is something different , how it works I will tell you …

When Android phone users turn on their Google Maps app with GPS location enabled, the phone sends back bits of data, anonymously, to Google that let the company know how fast their cars are moving.
Google Maps continuously combines the data coming in from all the cars on the road and sends it back by way of those colored lines on the traffic layers
As more and more drivers use the app, the traffic predictions become more reliable because Google Maps can look at the average speed of cars traveling along the same route.
If Google Maps doesn't have enough data to estimate the traffic flow for a particular section of road, that section will appear in gray on the traffic layer
Also with its acquisition of Waze in 2013 , Google added a human element and drivers started contributing about the slowdowns , speed traps etc which in result made certain points on Google Maps , with small icons representing a dash .

Please next time you have such questions, go to [url]Quora.com[/url]
Nairaland is dumb as F.

Nice one there