This paper investigates the formation of employment sub-centers from a new perspective of heterogeneity in agglomeration economies. Using highly granular commercial and residential land-use data (2001-2011) in Chicago, we measure how the locations of jobs, population, quality-of-life amenities, and transportation networks shape specific and heterogenous sub-centers. First, the results suggest that the CBD as it was traditionally defined is no longer the primary source of agglomeration externalities for the new economic sectors; sub-centers with sectorspecific positive agglomeration externalities have stronger correlations with new commercial establishments. Secondly, residents appear to give the highest weight to quality-of-life amenities in choosing where to live. Both trends imply dis-incentives for CBD agglomeration. These findings connect the heterogeneous production theories with land use planning and urban design, through new empirical insights into how urban sub-centers grow. Furthermore, we put forward a method for forecasting of future sub-center growth through measuring changes in the probability of commercial development, and discuss its practical implications for planning and design in Chicago.

The polycentric idea has recently been reinvigorated in many rapidly urbanising countries, but the paucity of reliable and disaggregated data has so far made it almost impossible to understand the policy feedback there. This paper capitalises on official statistical data, novel online data, and proprietary digital data, and builds a dynamic spatial equilibrium model for understanding the past lessons and future options for developing new urban sub-centres. Following the post-2010 situation of a negative sign of monocentric bid-rent curve and physical polycentric growth, we assemble, corroborate, and validate multi-source data sets within the model to explore possible polycentric development scenarios . The data analysis and model tests show that over time, the balance between jobs and housing provision appears to have been lost, and it is insufficient job opportunities in the planned sub-centres rather than any lack of housing development that has led to the loss of this balance. Localised circumstances have also played a role in this overarching pattern of evolution. The insights are cogent for current decision making regarding polycentric planning and growth, especially in developing countries.

This article first provides a critical scoping review of empirical literature on the relationship between urban structure and travel in China. The review finds that residential suburbanization alone increases travel, polycentric development has mixed effects, and jobs–housing balance reduces travel. Second, this article compares the empirical findings of the urban structure–travel relationships in China with those observed in other countries, and it identifies contextual factors that can explain the differing relationships in China. We suggest that future research improve data and methodology and broaden the research scope to investigate the complex mechanisms that affect the urban structure–travel relationship in China.

No abstract