Particular unloading with roof tiles
In the event that the roadway slopes down towards the valley, the unloading will be carried out by arranging roof tiles. At the discharge point, the soil is protected from localized erosion by using Reno mattresses.
See the photo gallery of a road drain

In this photo gallery, the rainwater drainage channel is made with vibrated concrete roof tiles of
the type published here and drains the water into a collecting sump.