Google Maps traffic how does it work?

[Zak33]

Hello people

Please can we tak about Googlemaps and in particular Traffic showing on it?

I use Googlemaps every day now, having a car with no inbuilt Satnav. I also use my google accoount on my work PC, so if for example I'm looking to see where a US based company works, as I did yesterday, when I sit in my car to go home, the recently searched addresses from my work PC shows in my phone, and frankly that's a pain in the backside, but it's easy to sort.

The anticipated journey time IS painfully accurate.

But I just don't understand why the traffic build up, shown in red, is utter nonsense.

Any got an idea how it works?

[Smudger]

Well, for me, it's one of two things, the UK has traffic monitoring over a large part of the road network, and this is used to provide data, first seen in the likes of the Trafficmaster system you used to see on Vauxhalls. But I think Google's system (and possible TomTom's and Garmin's, etc) uses live data passed back by users' devices. It's just that we don't know it's happening. False reports could just mean that a particular user has slowed down at a particular point, and the AI sees it as a build up.
Could be completely wrong though...

Edit: It seems I'm not:

https://www.quora.com/Where-does-Goo...-can-reference

When you choose to enable Google Maps with My Location, your phone sends anonymous bits of data back to Google describing how fast you're moving. When we combine your speed with the speed of other phones on the road, across thousands of phones moving around a city at any given time, we can get a pretty good picture of live traffic conditions. We continuously combine this data and send it back to you for free in the Google Maps traffic layers. It takes almost zero effort on your part — just turn on Google Maps for mobile before starting your car — and the more people that participate, the better the resulting traffic reports get for everybody.

The data is at least anonymised, so couldn't be used to get you for speeding...

[kalniel]

They also use Waze's database of user-submitted reports.

[Zak33]

well in my experience the following HAS happened.

I was driving along a normally quiet lane and the traffic ahead showed as red and slow for a mile...

when i GOT to that section, there was a sponsored bike ride and I guess all the mobile phones in all the bike riders pockets showed the road as clogged and slow....

so that DOES make sense....

but on the way to or from work regularly, I get to a place where it often shows as a traffic blockage in red.. and there is no blockage. At all.

[DanceswithUnix]

I think the speed boundaries used for how red a road is painted aren't right. Bits of motorway with a 50mph speed restriction will paint as congested when they are flowing just fine.

I suggest you use Waze rather than Google maps. Google owns Waze and there is some sharing of data, but the Waze app still just does the job better for car navigation. Just remember that when the app starts asking you questions that tapping the screen in a car with the engine on is a crime in the UK, the prompt will time out fast enough.

Waze does occasionally put me onto the M25 when it is lit up worryingly red, but it seems to be able to tell that the traffic is still moving for the one junction that I need. I have also learnt to trust that if Waze says get off the motorway, there is probably a big shunt up ahead and I do want to be on the backroads.

[DanceswithUnix]

when i GOT to that section, there was a sponsored bike ride and I guess all the mobile phones in all the bike riders pockets showed the road as clogged and slow....

I find my phone can tell when I am cycling, though in stop start town traffic it can think I am walking instead. If the cyclists hold up motorists though, then even just a bit of delay would show up for those motorists.

Edit: That is taken from when I used to get the Google cards for "how much exercise I did in the last month."

[MaddAussie]

Another vote for Waze for me, I'm currently in Bedford doing my Cloud MCSE, on the way up here it had me jump off off the M25 for 1 junction, instead using the Heathrow perimeter road as it obviously knew that section of road was faster/ less congested. When I go to Le Mans each year Waze data is updated by the ACO (Le Mans organisers) so Waze is the best way to get around the Jams and road closures.

[Zak33]

What if, and it's something that has just occured.....

what if there's a bus stop and the bus has 40 Googlemap phones on it?

[Zak33]

ooooooooooooooooohhhhhhhhhhhhh hang on....

where I get the problem is a RAIL WAY TUNNEL... what if a train stops on the top of it?

[Zak33]

i checked the map on stopped buses today... didn't show red.

What's the time delay, any idea?

[scaryjim]

What if, and it's something that has just occured.....

what if there's a bus stop and the bus has 40 Googlemap phones on it?

If the phones are reporting their speed back to Google, as the quote earlier says, then the algorithms can probably detect a stop-start journey like a bus route fairly easily, as the phones will vary from stopped to 20+mph on a regular basis (and of course, if they send speed and position the algorithm can identify that they're stopped at/near a bus stop). In fact, I'd go so far as to say they probably track historic speeds and progress and only indicate heavy traffic when a certain volume of reports are at a certain percentage of the typical average speeds for that route.

As to trains stopping, again over time they can track those phones and easily identify that they're on a train rather than a road, so they shouldn't contribute to the algorithm.

OTOH, I suspect you have hit on the true cause - or possibly two causes. First, the obvious one - a lot of phones are going to lose GPS signal in the tunnel, so you'll have a black-spot where Google don't know what the traffic is really like. When my GPS signal drops on the biking apps I use, the phone slowly ticks down to reporting 0mph, and when it gets signal again it takes a few seconds to get back up to real speed. So if the same thing happens with the reporting back to Google, they're going to think everyone slows down when they enter the tunnel and speeds up again when they leave.

The other thing I've noticed when I'm biking is that skyline obstructions - particularly trees, but sometimes tunnels as well - can reduce the reported speed from GPS tracking. I'll drop a couple of MPH under trees despite knowing I haven't slowed down. So that could also contribute to google thinking there's heavier traffic under the tunnel.

[DanceswithUnix]

Busses and trains also have wifi, and Google are good at detecting MAC addresses.

[Butcher]

I suggest you use Waze rather than Google maps. Google owns Waze and there is some sharing of data, but the Waze app still just does the job better for car navigation. Just remember that when the app starts asking you questions that tapping the screen in a car with the engine on is a crime in the UK, the prompt will time out fast enough.

It's only a crime if you're holding the phone; if it's in a holder you are fine (driving without due care and attention notwithstanding).

[Smudger]

It's only a crime if you're holding the phone; if it's in a holder you are fine (driving without due care and attention notwithstanding).

I believe the laws were tightened up in March so that touching it in any way during your journey is an offence:

http://www.chroniclelive.co.uk/news/...iving-12707634

Particularly:

I use my mobile phone as a satnav system, it sits in a cradle with the destination programmed in before I set off. For most of the journey I have the screen turned off. Is it OK to then unlock your phone using finger print scanner to bring satnav back up after the screen has been locked?

If the mobile phone is held in a cradle then it must not be touched throughout that journey. The moment you touch or handle your mobile phone as part of your journey, then in effect an offence is being committed.

[Saracen]

I believe the laws were tightened up in March so that touching it in any way during your journey is an offence ....

I think the ambiguity comes from the word "use".

A mobile phone is legal to use while driving provided you don't touch it during the journey. So, following a SatNav route is okay, but setting up or amending it by touching the phone is not. Answering or making a call is legal providing it is entirely hands-free, but touching buttons to do so is illegal. In either case, SatNav or calls, or any other use of phone or internet device for that matter, doing anything with it dfuring a journey that isn't hands free is illegal. Doing it other than hands free while stopped in traffic, or at red lights, etc, is still illegal.

If you need to use hands, pull over, park and engine off.

The above relates specifically too the new-ish phone legislation, but on top of that, and Butcher referred to it, there is still offences of not being in proper control, due care and attention, etc, that apply to all drivers at all times while driving. So if you are distracted, not in proper control or not paying "due care and attention" there is a potential for an offence. Anything meeting those standards, be it adjusting a radio, eating a ssandwich, picking your nose, applying make up, etc, could qualify.

Perhaps the biggest difference, though, is that the latter require you to not be paying attention or be in proper control, whichnare more subjective, subject to dispute and harder to prove. But the mobile phone offences, if you get caught doing it, it's open and shut, and a LOT of police cars have onboard vidro cameras these days.


Personally, I still prefer stand-alone SatNav. It's neither a phone nor an internet device, and so isn't covered by the more draconian (and justified) mobile phone rules. I do still have to be aware of proper control, due care and attention, etc, and am glad I can reprogram routes, waypounts, etc, by voice control, as it avoids argument .... though technically, even that could constitute sufficient distraction to meet due care and attention, as could answering a phone call hands-free IF you are sufficiently distracted.

As always - IANAL and this isnt advice.

[Smudger]

Does Google Maps do alternative Routes? I know on my TomTom, if there's a traffic incident, I can touch the screen to choose an alternative, but on a phone, it wouldn't be possible. Not sure if you could do it by voice?

- There is an alternative route. Do you want to choose it?
- Yes
- I'm sorry, I didn't understand your response.
- Yes
- I'm sorry, I didn't understand your response.
- @$£*ing YES!"!!!
- OK, changing endpoint to Scotch Corner Dogging Layby. No further changes allowed.