Background information
20 years of Google Maps: much more than just a digital map
by Jan Johannsen
Simulating a traffic jam on Google Maps: not impossible...
10.2.2020
In Berlin, an artist has created a virtual traffic jam on Google Maps by walking along a street with 99 mobile phones. Will we manage to reproduce this Google Maps Hack in Zurich or is the video a fake?
The video went viral: some guy pulling a squeaky red trolley behind him. The cart is filled to the brim with smartphones. The artist's name is Simon Weckert. His trusty cart by his side, he walks right along a Berlin street. Then his Google Maps location flashes on-screen. The road is empty and the map section green – until the section suddenly turns orange and finally red.
With his GPS truck, Weckert managed to get Google Maps to show a traffic jam even though the road was almost car-free. But is the video real? Can it be? Is Google Maps so easy to influence?
There's really only one thing left to do: my colleague Dominik Bärlocher and I are doing some tests.
What we know from the video
We quickly realised that you can't just stand on a street with a few cell phones and hope for a Google Maps traffic jam. So we analysed the video in more detail. The following points have come to our attention:
No public transport
If a few phones on a street could already create a Google traffic jam, then every bus or tram stop would display them. The average trolley bus can fit over 114 people. That's more than the 99 mobile phones that Weckert had in his little cart.
Our research showed that neither of the two locations chosen by Weckert – Schillingbrücke and Ebertbrücke in Berlin – contained public transport.
Google most likely removes bus routes from its calculations. A bus route doesn't change and almost all public transport timetables are stored in Google Maps. We can therefore assume that Google applies a different tolerance limit for traffic jams on bus routes than on roads without public transport.
Navigation Mode
The video shows that Weckert had all phones in navigation mode. He entered a destination and followed a car route. Google is definitely actively processing location data.
However: Google Maps also transfers data when the app isn't active. As long as Google Maps has permission to query your location data, Google can and will record your movements. You can view this in your Google Maps Timeline.
In theory, it should be possible to fake a traffic jam using only phones with Google Maps and location data enabled.
Traffic jam length: map sectors
In this video screenshot, you can see that roads always turn red in sections, i.e. sectors. Weckert's jam first affects about half the bridge, later the whole, then a shorter section again. One glance at Maps tells us that the bridge is about 70 meters long. With 99 phones, this results in an average distance of about 70cm
Since Google knows that there is one car lane per direction on the bridge and that there are two sidewalks, Google assumes that the 99 smartphone owners will walk one behind the other. They can't fit next to each other.
This raises a point. Your Google location will always be «accurate to 20 meters». This is a great explanation for why the jam moves so accurately: Google's high-accuracy mode. With it, your location is more accurate than when using GPS. With this setting enabled, Google knows that there are too many people on the bridge, and will therefore display a traffic jam.
The experiment
After our research, we know: it should be possible to simulate a traffic jam with the right amount of smartphones. Provided two basic factors are observed:
- You're not on a public transport route.
- Your phone's location data activated.
Time for our experiment.
As we don't really have 99 mobile phones lying around the editors' office, a major organisational exercise is called for. One chain mail, one Doodle, many labels and lists later, we've borrowed 47 mobile phones from our colleagues. First and foremost, we ask those who entrusted us with their phones to activate Google Location Services. We use every device, whether Android or iOS.
On top of these 47 mobile phones with SIM cards, we throw in seven mobile phones without SIM cards that we have lying around. That adds up to 54 smartphones.
We keep our own phones close at hand so that we can track what's happening. In order to see the traffic jam on Google Maps, we entered the corresponding route and then switched to navigation mode.
56 phones, all working as one. This is less than in the Berlin video, but still enough to make us believe in the traffic jam.
We chose three specific road sections that we wanted to virtually congest.
First route: Giessereistrasse, 8005 Zurich
Giessereistrasse, located right in front of the digitec shop, seems suitable to us due to the following factors:
- No public transport.
- Little car traffic.
- The narrow, small street.
Some of the digitec employees who gave us their phones were sitting in the building across the street. That's why we only had 43 phones at first. As we still had some time until we got the rest, we tried to create a traffic jam with only these 43 mobile phones. But it shows: we can't get a traffic jam. Even after walking back and forth for more than five minutes, Google Maps doesn't display anything out of the ordinary.
We're worried. Is it going to work? Is the viral video a fake or do we have too few mobile phones even for this small street?
We picked up the remaining phones. The rest of the employees show up and we chat for a short while at the corner in front of the digitec-Café. Suddenly we notice: At Förrlibuckstrasse crossing, we had already unintentionally created a traffic jam. The display was red, although only a few cars were passing by.
Back at Förrlibuckstrasse, our first test track, the result quickly becomes clear: after a few minutes, Google Maps displayed a yellow, then a red traffic jam. We reproduced this several times. Therefore, 56 mobile phones are enough to fake a traffic jam on a small road. We can even shift the traffic jam in the direction of Puls 5, as the crossing Giessereistrasse/Technoparkstrasse contains a sector border. We assumed that Google has a different congestion tolerance limit there – just like further along the road.
The sectors probably run from congestion point to congestion point. This could be a crossroads, a bend or the middle of a bridge. However, only Google itself can provide a conclusive list including an explanation of the sectors.
Second route: Förrlibuckstrasse, 8005 Zurich
Förrlibuckstrasse is a bit bigger. We chose it because it has:
- A lot of cars on it.
- No public transport.
- Few pedestrians.
- Wide roads.
We already found out that we can virtually dam the crossing Förrlibuckstrasse/Duttweilerstrasse. Although there are some traffic lights, 56 phones are too many GPS signals for Google to guarantee smooth traffic flow. So logically: a traffic jam must follow.
Now we wanted to know what the rest of the street would look like. We are in the middle of the road between Duttweilerstrasse and the parking garage P-West.. And after several minutes of trying and waiting: we can't jam the section.
We suspect that the parking garage, which is right next to the road, is the reason. Google Maps must have learned that there are many cars driving around slowly all day. Due to Google's measurement inaccuracy, the «Parking Garage» field overlaps with the street. That's why Google Maps knows that many cars turn slowly on the road. This puts the limit higher and explains why we can't manage to fake a jam.
This again confirms our assumption: each Google Maps street type has its own traffic jam limit. Larger roads need more cars, but smaller roads get congested from just a few phones. In addition, there are other factors, such as the parking garage, but also recurring rush hours, which Google knows and will take into account.
Third route: Pfingstweidstrasse, 8005 Zurich
As the main traffic axis of Zurich, Pfingstweidstrasse has it all:
- Public transport.
- Countless cars.
- Pedestrians.
Pfingstweidstrasse would have been the final boss for our experiment. As a motorway feeder road, it's constantly busy and tram stops for line four dot the right side of the road.
After we already failed at Förrlibuckstrasse, we didn't expect to be able to create a traffic jam here anymore. For the sake of completeness, we still stood on a traffic island in the middle of Pfingstweidstrasse and waited. Nothing happened.
Too many factors telling Google that there couldn't be a jam.
In addition, hundreds of cars were passing us. The 56 GPS signals were probably regarded as an anomaly by Google and deducted. If hundreds of other signals are advancing at high speeds, there can't be a traffic jam.
Our Conclusions
With 56 mobile phones, it's possible to congest a small street if enough factors apply. On larger roads, this becomes difficult or impossible. We also learned a lot about Google Maps.
These are the most relevant points:
- Many factors are included in estimating a traffic jam.
- Google is powerful and clever.
- Maps detects anomalies quickly.
- The jam indicator is fast.
- But we don't really know anything.
The traffic jam indicator on Google Maps is a goliath. As a mere human, you can hardly keep up. And just because a traffic jam could be produced here today doesn't mean that it will still work tomorrow. Google is constantly working on the App.
When Google was confronted with Weckert's art project, here's what they told tech magazine 9to5Google:
Whether via car or cart or camel, we love seeing creative uses of Google Maps as it helps us make Maps work better over time.
Simply put: Google is constantly working to improve data quality. It's conceivable that Weckert's and our hack only worked because not many people would come up with such an idea.
Google's jam function is powerful. If you see a traffic jam in the app, you'll avoid the route and take a detour. However: how many people really use Google Maps when driving? Many cars have built-in navigation systems or expensive navigation devices such as those from TomTom. Then there are motorists who know their route and drive around without a navigation system.
However, Google Maps is becoming increasingly popular, especially in large cities, as this is where the traffic situation is most up-to-date. That's why this hack is so powerful. But even though it's all very cool: don’t try this at home, and be careful around roads!
Testing devices and gadgets is my thing. Some experiments lead to interesting insights, others to demolished phones. I’m hooked on series and can’t imagine life without Netflix. In summer, you’ll find me soaking up the sun by the lake or at a music festival.
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