When driving through a **tunnel**, it is important to maintain a **minimum distance of 100 meters** from the vehicle in front. This distance is crucial to ensure safety, as tunnels are enclosed spaces where conditions can be more challenging, such as reduced visibility and lack of space for emergency maneuvers.

- **Safety distance**: Maintaining at least 100 meters allows enough time to react to any unforeseen events, such as sudden braking by the vehicle in front.

- **Exception for heavy vehicles**: Vehicles that can carry more than 3,500 kilos must maintain an even greater distance of **150 meters**, due to their greater weight and the additional distance they need to stop.

These measures are part of the **preventive driving** rules, which aim to minimize risks and avoid accidents in situations where visibility and space are limited, such as in tunnels.