**Lateral barriers** are safety elements on roads that help protect vehicles and their occupants in the event of an accident. There are different types of lateral barriers, each with specific characteristics:

- **Displaceable lateral barriers**: These barriers are designed to move or give way under the impact of a vehicle, thus reducing the force of the crash and minimizing damage to both the vehicle and its occupants.

- **Semi-rigid lateral barriers**: These barriers combine rigid and flexible elements, providing a structure that can absorb part of the impact while maintaining its shape to redirect the vehicle back onto the road.

On the other hand, the term **"inaccessible lateral barriers"** does not refer to any recognized type of barrier in the context of road safety. There is no type of barrier with this designation, making this option incorrect or non-existent in the context of lateral barriers.