With urban and economic restructuring, facilitating urban regeneration for rundown post- industrial cities has become a central urban planning policy objective in Western cities since the late twentieth century, leaving some centres in prolonged social and economic decline. This chapter explores one example of planning policies seeking to regenerate an urban centre. Our focus is Newcastle, approximately 160km (100 miles) north of Sydney, Australia. Newcastle has a long history as an industrial city, dominated by manufacturing and coal-mining in the surrounding Hunter Valley. The port of Newcastle remains the world's largest coal export port. In 1999, BHP closed the Newcastle Steel Mill, triggering industrial restructuring and catalysing significant urban transformation. Despite a flurry of planning activity, regeneration of the central business district (CBD), waterfront and brownfield industrial sites has been slow. The most recent round of planning for the Newcastle CBD saw the release of the Newcastle Urban Renewal Strategy in 2012 ( 2012 NURS ) (DPI, 2012) and its revision in 2014 ( 2014 NURS ) (DPE, 2014). Arriving two years after the original, the 2014 NURS presents a significantly different urban future, premised on ceasing the heavy rail services into Newcastle CBD, to be replaced by light rail (among other developments). We explore these strategies aided by the Actor Network Theory (ANT) concept of translation. Planning documents convene social actors and define the relationship between material and non-material (physical) actors (Rydin, 2013) creating new meanings that build from both the social and physical characteristics of places (Bylund, 2013). They work as intermediaries and mediators that circulate to create and maintain urban change networks (Rydin, 2013). In adopting an ANT framework, our approach is 'strategic and illustrative, rather than comprehensive' (Jacobs et al., 2007: 609). The decision to truncate the heavy rail line disrupted the 2012 NURS , which sought 'to recommend an integrated package of initiatives aimed at developing a solid basis for the long term successful renewal of the city centre' (DPI, 2012: xvi). In exploring the central role of rail infrastructure in Newcastle planning, we adopt a socio-technical perspective that recognizes plans and transport systems as combinations of technologies, institutional arrangements, market processes, legislative frameworks, human agents and non-human actants. We trace the way planning in Newcastle has centred on the extent to which alternative socio-technical networks - different rail systems - can become stable, resist challenge and seek to define the future city. The first section of this chapter reviews ANT as a theoretical approach to planning and, drawing on this approach, the second section explores the planning process in Newcastle, focusing on the proposed replacement of the existing heavy rail system with a new light rail system.