Electrification of the Great Western railway between London and south Wales in the UK required the design and installation of 13 000 individual foundations for overhead line equipment along 650 km of live railway tracks. A key design requirement was to provide a simple method of allocating large volumes of foundations while providing a robust design for the wide range of ground conditions, topographies and loading regimes. This paper summarises the key geotechnical design considerations and the basis of design that was used. It then discusses the practicalities and experiences of the various construction techniques that were adopted, focusing on sections of the route where shallow rock was present.