Abstract: Public transport unions are key actors in transport policy in Australian cities. Historically, dramatic industrial disputes made this role highly visible. This paper uses a case study of union power in public transport in Melbourne since the mid 1990s to show that union power remains a significant, though now largely hidden, obstacle to modernisation of the design and delivery of public transport in Australian cities. In Melbourne, public transport unions have a history of considerable power and influence. Since 1992, union power in public transport operations and policy might appear to have declined under the influence of neo-liberal reforms. However, union activity was responsible for a significant proportion of the train cancellations that brought the rail system to near-collapse in January 2009. Through reporting of interviews with key protagonists and analysis of available public documents, this paper provides evidence that union power remains a strong influence on the operations of Melbourne’s public transport system and, in light of current power dynamics, provides an additional impediment to necessary reform of public transport service design and delivery.