An autonomous taxi service has been proposed as a sustainable urban transport system for current and future cities. A critical review was conducted to examine whether the proposed technology can alleviate the negative side effects of urban transportation. The study investigated issues related to environmental impact, social sustainability and required infrastructure. A methodology was proposed to estimate the levels of demand and define the system performance requirements for an autonomous taxi to serve Addenbrooke's, which is a medical and research campus at the University of Cambridge UK. The size of the fleet, the capacity of the on-board battery and a charging infrastructure were suggested. Implications for the electricity supply network were also explored. A financial analysis showed that such a system is financial viable.