How Google Recognizes Traffic Jams on Maps
Berlin-based artist Simon Weckert recently “hacked” Google Maps, filling a red car of 99 iPhones with Google Maps installed and dragging it around town to trick the service into thinking there was a traffic jam and there wasn’t.
It’s a clever trick, but it raises questions about how Google Maps tracks and responds to the data it collects under normal driving conditions. If you can fool Google Maps with a pile of old iPhones and a shopping cart, can you always be sure the app is accurate? Based on what we know about the Google Map algorithm and the company’s reaction to the traffic congestion in Weckert, it seems so, for the most part.
How traffic jams are displayed on Google Maps
Google Maps is constantly updated based on anonymously tracked user data , traffic sensors and satellite data to ensure the app displays the most accurate traffic conditions.
If you’ve ever used Google Maps, you’ve probably seen streets in green, orange, or red. Green roads indicate normal traffic, while orange and red roads indicate deceleration. Slowdowns occur when users in Navigation Mode are currently driving slower than normal on that stretch of road and are automatically applied by Google. However, once other divers using Google Maps can pass through the area at normal speed, Google will remove the deceleration status for that area, even if other users are still moving more slowly.
It’s unclear how many slower-than-normal users need Google Maps to register this as slow traffic, but according to 9to5Google’s report on Weckert’s traffic jam experiment , it only took one car passing by at normal speed to clear the traffic jam. … the status is brought about by its versatile iPhones. However, it seems like Google Maps is ignoring when many users are idle. Weckert’s van had to move for Google Maps to see the traffic jam, although nearly 100 phones were in navigation mode and did not move. How long a car must be idle before being ignored is unclear; obviously Google Maps will notice if multiple users stop on the highway and report it as slowing down, but if a group of people are parked in the garage and just accidentally turn on navigation mode, you probably won’t see any traffic jams listed in the area.
Interestingly, not all cars are treated the same. Google Maps can distinguish between cars, motorcycles and other vehicles (at least in certain countries and regions). So, even though a cheeky scooter might wade through a traffic jam, Google Maps can – in some cases – recognize that a smaller vehicle’s movement does not necessarily mean normal driving conditions have resumed.
Accidents, construction and other road traffic accidents
Google Maps also updates traffic reports based on user input, in addition to passive anonymous location and traffic tracking, to keep conditions up to date.
Accidents, construction zones, speed traps and other warnings can be reported on Google Maps, and the more users report the warning, the faster it appears on the map for others and potentially helps them avoid slowing down and find better routes when needed. We’ve previously covered how to do this on Android and iOS, but here’s how to report traffic incidents and slowdowns in Google Maps if you’re not familiar:
- While in Google Maps navigation mode, tap the “+” icon (the third icon at the bottom of the right-hand menu).
- Tap the icon for the type of incident you want to report. Follow the instructions on the screen to complete the submission.
- The app will start adding the report to the map, although you have a short countdown window to cancel the report if you want to cancel.
Calculation of routes and estimated time of arrival
Google compares the speed of its users with information about the speed limit to calculate an approximate time of arrival . Basically, it depends on how fast you are actually going, how fast you have to go depending on the speed limits, how fast other drivers are traveling and how they adjust, and how far you have a route to determine your estimated time of arrival.
Google Maps will also compare user-reported conditions and other traffic data that is tracked against your route and current speed, and adjust your arrival time if they notice any slowdown or other incidents along your route. Once the app determines the severity and duration of the slowdown, it will alert users whose routes are affected and suggest alternative directions if they end up faster.
However, Google Maps’ suggestions for re-routing are not always ideal. The algorithm can only respond to the most recent data and make assumptions – it certainly cannot predict the future – so rerouting will not always be faster (or necessary). However, you can be reasonably confident that the application is providing you with the latest information.