Chapter 12: Drainage of pavements

Drainage is recognised as being important for both the functional and structural condition of a pavement. Nevertheless, comprehensive guidance on its design, and especially its maintenance, is not easy to find.

Figure 12.1, which originated in the early 1950s (TRRL, 1952), illustrates that there are several issues relating to the drainage of a pavement. They are considerably broader than just the rain that falls on the surface, which, if not removed efficiently, may lead rapidly to a serious reduction in safety due to standing water. Surface water is managed by a range of features, from permitting overrun onto a hardened shoulder, as shown on the left-hand side of the figure, to the provision of channels and gullies leading the water to some form of piped system adjacent to or underneath the pavement or to adjacent ditches.