Underground pedestrian systems development in cities: Influencing factors and implications

Underground Pedestrian System (UPS) has been developed around the world especially within the central areas of mega cities during the past century. UPS development has occurred for various reasons. Factors from both natural and built environments have contributed to UPS developments in major cities around the world. In cities with severe weather conditions such as Toronto (Canada), a cold Winter City and Oklahoma City (United States), a windy city, UPS have provided a climate-controlled environment for social, entertainment, retail and commercial activities. In dense urban settings such as Tokyo, Japan and Shanghai, China, UPS provide opportunities for much more comprehensive and intensive usage of urban spaces, by accommodating multiple urban functions that is comparable to that which occurs at street level. This research selected 19 UPS cities as cases studies to explore the prevalence of the four influencing factors namely climate, subway construction, land usage and the economic environment. The research revealed the degree of prevalence of these four aspects for UPS cities and determined the differentiating factors of the natural and built environments that resulted in the establishment of UPS. Further analysis based on SPSS statistical tests examined the differences between developing and advanced economies in relation to the prevalence of these factors. The research findings indicated that there are statistically significant differences that help to explain the existence of UPS in developing and advanced economies according to economics, the presence of subway systems and city scale. These differences highlight the different stages of urban development of the studied cities, typified by differences in urban spatial structure that are apparent when comparing cities in developing and advanced economies.