He completed his PhD at the University of California, Berkeley, in 1999, and has since been working in transportation consulting, research and teaching in South Africa. His research interests include travel behavior modeling, land use/transport interaction, planning for public transport, and the social and economic impacts of access and mobility. Recent work include analysis of access and mobility patterns in Gauteng townships; modelling of transport captivity in Johannesburg using stated preference data; assessing the poverty impacts of the Rea Vaya Bus Rapid Transit system; and using personal GPS devices to help understand walking behavior in poor communities.