Introduction

Abstract

This introduction provides a brief review of the history of highway sub-drainage before setting out the aims and organisation of the book of which it forms the first chapter. It gives an overview of the subjects to be covered in the following chapters, introduces the key topics including definitions of subgrade and pavement layers, their classification from a drainage point-of-view together with a brief coverage of the principle of effective stress, suction, leaching and water movement due to evaporation and frost-heave. It outlines the way in which pavements and the hydrological environment interact before introducing the reader to the varieties of climate in which highways and pavements have to operate – a task that is likely to become more onerous in the light of climate change effects.