How does Google Maps work ?

Ebe_Scrooge · 11 December 2019 at 3:24PM

I rarely have the need for a Satnav, but on the odd occasion I do need one I just use Google Maps on my phone. One thing that impressed me is how it knows about traffic jams. I was on a dual carriageway recently, it warned me of slow traffic for a mile, and it was spot on - the jam started and cleared exactly where it said it would.

There were no cameras anywhere around that could be sending data to them - no speed cameras, CCTV, speed monitoring devices, nothing I could see. So how did Google know ? Has it got satellites that can see the traffic or what ? If it is satellites, they must have a lot to be able to see every road in the world in real time. Just curious :-)

stripeyfox · 11 December 2019 at 3:27PM

Presume it collects data from yours, and everyone else's phone which averaged out, gives an accurate picture of road speed?

EDIT
The green, yellow and red routes that Google Maps uses to indicate clear, slow-moving, or heavily congested traffic are a great help when you're trying to determine the fastest way to your destination, but how does Google know the traffic conditions between where you are and where you're trying to go?

Google Maps bases its traffic views and faster-route recommendations on two different kinds of information: historical data about the average time it takes to travel a particular section of road at specific times on specific days and real-time data sent by sensors and smartphones that report how fast cars are moving right then [source: Barth].

Neil_Jones · 11 December 2019 at 3:38PM

Its based on the principle that most people who don't change any of the settings will have mobile data on*. Google Maps can use this to pinpoint where you are and know how fast you're moving. If a certain point on the road network is always congested at 8:30am on a weekday morning (which to be fair is probably a large chunk of them) then its probably safe to assume it will be congested today, and if data that Maps can grab shows similar data, it gets flagged as such on the map.

That's all it boils down to - real-time sensors, smartphone information, location services. I dare say if a road accident was caused by somebody farting and setting light to the gas tank causing the car to go flying through the air (yes I know it's incredibly far fetched!), all the traffic waiting would feed back to Google and the system would know there's an accident on the Wallaby Road, all these cars are stuck in the one place, its either congestion or an accident. If not at a junction, its probably an accident.

Of course its not perfect. Google Maps quite happily told me the other day a big accident on a dual carriageway and tailbacks over three islands worth, but by the time I got there the accident and the tailbacks had promptly vanished into thin air.

*Note that if you don't have mobile data, then I believe Google Maps can remember the movements of the car and its speeds and whatever else and feed it back later when you're on Wi-Fi to add to the historical history to aid future journeys.

DigForVictory · 11 December 2019 at 3:46PM

The algorithms are pretty good but not until they have enough phones static at a given location. Says she recalling getting stuck on a road that displayed green, then turned amber & then red. We got there a little too early, from Google's perspective....

Sea_Shell · 11 December 2019 at 3:48PM

Can also be skewed by parents sitting, parked roadside, waiting for school kickout time, surfing the net!!

Neil_Jones · 11 December 2019 at 3:53PM

No system is perfect. It never can be. Unless Google want to employ somebody to stand on every piece of road in the country 24/7 and manually feedback "accident, congestion, broken traffic lights, etc" every five minutes, an automated "guess" with the balance of probability is the best we can get. It is impressive but it will never 100% correct.

molerat · 11 December 2019 at 4:19PM

The systems are not all that smart though. There is a local B route which used to be "locals only". Sat navs routed along the A roads but as devices advanced all the in the know local's data showed that the B route was quicker. Now it routes busses and lorries along this totally unsuitable route, nothing quite like seeing the terror in the eyes of a foreign tourist not used to single track roads.

Ebe_Scrooge · 11 December 2019 at 4:24PM

Thanks for the responses - very interesting. I'm absolutely not in the tin-foil-hat brigade, but it's interesting just how much we're being monitored. Yeah, I know the same is true every time we walk down the high street that's covered by CCTV etc., and it doesn't worry me. Interesting though.

bob_a_builder · 11 December 2019 at 5:49PM

Google owns the Waze app too

Its another navigation app but includes a feature where real people give real time feedback about whats happening in front of them, so gives them more date to feed into the navigation mix

Google maps has also now started to introduce the human feedback option too via the "Add a Report" function ( press the up arrow at bottom of screen when navigating )
You can inform about Crash, Mobile Camera,Congestion,Roadworks etc etc

bob_a_builder · 11 December 2019 at 5:50PM

I'm absolutely not in the tin-foil-hat brigade, but it's interesting just how much we're being monitored.

Ebe Scrooge : Take a look at the TimeLine feature of Google Maps if you haven't already

RumRat · 11 December 2019 at 7:54PM

molerat wrote: »

The systems are not all that smart though. There is a local B route which used to be "locals only". Sat navs routed along the A roads but as devices advanced all the in the know local's data showed that the B route was quicker. Now it routes busses and lorries along this totally unsuitable route, nothing quite like seeing the terror in the eyes of a foreign tourist not used to single track roads.

It's not the system that isn't smart......;)

How does Google Maps work ?

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