Beyond rail: Amenity driven high-density development for polycentric cities

Introduction The ‘century of the city’ is marked by a fundamentally new set of environmental and urbanization trends that make the bundling of urban development and sustainability an imperative (Seto et al., 2010). This is especially the case for sprawling, auto-dependent polycentric cities that have seen rapid growth in the last few decades. Local governments in such places are striving to achieve the agglomeration benefits of increased density, such as greater efficiency and walkability, without incurring the negative effects of agglomeration (e.g. pollution, congestion and longer travel times). In polycentric cities where rapid suburban growth has been the standard for decades, high-density compact urban form is only achieved through municipal intervention in the form of public-private partnerships, development associated with new municipal infrastructure projects, or direct and indirect developer incentives. While uncertainties remain about the degree to which compact urban form is the silver bullet for all urban ailments, strong planning interventions to facilitate density garner widespread support (Ewing & Hamidi, 2015). In short, a critical aspiration of twenty-first-century polycentric cities is to increase high-density, mixed-use development, but the strategies for achieving such aims are limited in the face of ingrained greenfield, sprawl-oriented development paradigms (see also Bjelland & Noyes, Chapter 3 in this volume).