From network description to network performance: Preface to the special issue 'Urban Network Externalities'

In recent years, network analysis has been widely used to understand urban and regional organizational patterns and their spatial effects. A single city benefits from the scale economy of 'networking' in the inter-city synergy relationship. Some cities or regions also suffer from the loss of resources or elements due to more convenient connections to other cities. The traditional urban endogenous growth theory emphasizing agglomeration economy is no longer suitable to explain the urban and regional organization shaped by 'spaces of flow' alone. The externality of urban network has become another important factor affecting urban growth and regional integration. At present, the existing research (especially in China) is relatively scarce, and most of the studies focus on the spatial pattern and process of the network, and the effects (externalities) of network connections are relatively ignored, i.e., how the urban network externalities interact with the agglomeration economy, which types of cities will benefit or suffer from urban network externalities, and what are the conditions for generating urban network externalities. The above need to be discussed urgently. In order to call on academia to shift more attention on network research to the scientific exploration of 'what' and 'how' regarding the effects of urban and regional development and its optimization, this special issue has selected 15 related papers which carry out the systematic theoretical discussion and empirical research aiming at the 'urban network externalities'. They outline the research agenda on Chinese experience of urban network externalities, and use this as a starting point to promote the deepening of urban network research from pattern description to network performance.