William Johnston is regional director of WSP | Parsons Brinckerhoff, Structures, Africa. With 14 years' experience as a professional engineer in South Africa, Nigeria, Kenya and the UK, he has covered a varied range of projects, from a prestigious high-rise office block in central London, to the emergency rehabilitation of a township school in KwaZulu Natal; from extensions to Gauteng's largest sewage works, to the development of Africa's first "green" city in Pretoria.