This chapter examines megaproject design and planning in two “shrinking cities”- Philadelphia, PA and Detroit, MI- concludes that megaproject "metastasis", or repeated expansions into surrounding urban fabrics, is promoting the reduction of downtown into a series of self-contained enclaves. While political coalitions are constructing megaprojects, or large public works and/or single buildings, in cities around the world, in the United States, single-building megaprojects motivated by “growth coalitions” of public and private development actors have proliferated in downtowns since 1990.
The urban design impacts of these megaprojects on the surrounding urban fabric have been little studied. Data on the institutional history, physical expansion, and relationship of the megaprojects to the urban fabric is combined with a qualitative analysis of megaproject theory and its application to the American condition, as well as to the political economy of development in American shrinking cities. The chapter concludes that megaprojects such as convention centers and casinos tend to expand inexorably once they are introduced into the American downtown. This metastasis results in the destruction of existing older buildings and street networks, the consolidation of street blocks into ever-larger superblocks, and the eventual physical restructuring of downtowns into enclaves of older fabric amidst clusters of megaproject superblocks.
Applying Jane Jacobs' theory of "moral hybrids” between “commerce and politics" to megaproject metastasis, the chapter argues that while megaprojects may be inevitable in American downtowns, they should be sited away from active, small-scale urban fabrics to reduce the negative impacts of future metastases. The chapter takes a design-oriented perspective on a phenomenon that is almost always understood from a political economy perspective alone. Megaprojects are significant physical entities, and I clarify their physical impacts on the urban fabric while indicating urban design policy directions to reduce these impacts in future.