Highways provide the arteries of modern society. The interaction of road, rail and other transport infrastructure with the ground is unusually intimate, and thus needs to be well-understood to provide economic and reliable infrastructure for society. Challenges include not only the design of new infrastructure (often on problematic ground), but increasingly the management and maintenance of aging assets in the face of issues such as climate change. This book is the written record of the first International Conference on Transportation Geotechnics held under the auspices of the International Society of Soil Mechanics and Geotechnical Engineering, held in Nottingham, UK, in 2008. It comprises about 100 papers from a global selection of researchers and practitioners on: – Slope instability, stabilisation, and asset management; – Construction on soft ground; – Interaction with structures and geogrid reinforced soil; – Effect of climate change and vegetation; – Highways, pavements and subgrade; – Railway geotechnics; – Soil improvement; – Characterisation and recycling of geomaterials. A further part of this collection contains papers on unbound aggregate materials as used in pavement construction and drainage. They formed the ‘Unbound Aggregates in Roads (UNBAR7)’ theme of the conference which followed on from the previous symposia of that title, also held in Nottingham, UK, most recently in 2004. The volume will be of interest to professionals and academics in geotechnical, highway, railway and general civil engineering.