The sign "Vehicles with a permissible total mass over 3.5 tons" indicates that vehicles exceeding a total weight of 3.5 tons are either prohibited from entering a certain area or subject to specific regulations. This sign is often used in urban areas or near certain sections of roads where heavy traffic may pose safety risks, such as increased wear on the road or excessive noise.

In general, this sign is meant to protect smaller vehicles, pedestrians, and cyclists by restricting access to heavier commercial vehicles, which are usually trucks or large vans. If you encounter this sign, you must ensure that your vehicle meets the weight requirement or avoid that route if you are driving a heavier vehicle.

Always pay attention to any additional signs or signals in the area, as they might provide further information about restrictions, such as specific times of day when the restriction applies or alternate routes for heavy vehicles.