How traffic patterns keep speed limits updated

Imagery and data provide a solid foundation for our model of real-world speed limits. However, speed limits are constantly changing, which makes them challenging to update. Things like construction, community input and long-term traffic conditions may temporarily or permanently change the speed limit.

To tackle this problem, Google Maps analyzes traffic trends to understand if there could be a speed limit change. For example, if our trends show cars are consistently traveling below the speed limit, it might be an indication that the speed limit has decreased. This can happen if a new school is built or if a local government determines that a road is a high-risk area for accidents.

If we suspect the speed limit in an area has been updated, we cross-reference the change with multiple sources — like official data from local governments and refreshed Street View imagery — to confirm or deny the change. In areas where we don’t have recent Street View imagery available, we request images of the specific stretch from third-party partners that already gather roadway information to do things like improve delivery routes and road safety. If the partner has photos available, we use a combination of AI and help from our operations team to identify the sign in the images, extract the new speed limit information, and update Google Maps.

How our speed limit data is powering future driving technologies

This information is also useful for automakers building cars with assisted driving or fully automated driving features. For many of these features to work, cars need to know the speed limit just like a human would. Being able to do this accurately and precisely is becoming an ever-pressing issue for automakers — especially as more policies regulate assisted-driving features.

For example, the EU’s General Safety Regulations (GSR) require that new vehicles registered after July 2024 have an intelligent speed assistance (ISA) feature that displays the legal speed limit at all times and warns drivers if they go over it. To meet the requirements, vehicles must deliver accurate speed limits for at least 90% of any drive.

Cars’ built-in cameras and sensors can help car manufacturers capture some of the required speed limits. But there are similar challenges that make speed limit signs hard to detect like inclement weather, physical barriers and poor sign placement. So while vehicle sensors are a critical component — and will even help keep Maps updated for everyone — our data plays a big part in completing the picture for automakers. In fact, the ISA feature in Volvo’s EX30 just passed the EU’s GSR certification by using our speed limit data. This means that the EX30 can reliably display the legal speed limit, even when there aren’t clear signs on the road.

Speed limits play a big part in keeping roads safe for drivers, cyclists and pedestrians alike. And we’ll continue to invest in our technology so that automakers can build highly-accurate assisted driving features, and drivers can feel confident on roads anywhere in the world.