The **lateral barriers** serve the function of **indicating the edge of the platform**. This is important so that drivers can clearly identify the boundaries of the road and thus avoid leaving the roadway. Although lateral barriers are not directly mentioned in the provided texts, we can relate their function to the need to maintain an **adequate lateral separation** between vehicles and other elements of the road, as described in the second text. This separation is crucial for safety, especially in adverse conditions such as rain or fog. Therefore, lateral barriers help guide drivers and keep them within the safe limits of the road.