What indicates that a driver should not exceed a speed of 30 kph?

The round blue sign with a white number 30 is a standard traffic sign that clearly indicates a maximum speed limit of 30 kilometers per hour. This type of sign is specifically designed to inform drivers of the legal speed they must adhere to within that area. Speed limit signs communicate important rules for road safety, ensuring that drivers can adjust their speed appropriately to mitigate risks and enhance safety for themselves and others sharing the roadway.

In this context, a round blue sign specifically conveys a mandatory speed limit in a easily recognizable format, making it crucial for drivers to understand and follow for compliance with traffic regulations.