The Development of Underground Space as a Way to Optimize Urban Territory: a Case Study of the City of Kazan, Russia

Unlimited perimeter sprawl of a city at a certain stage leads to the emergence of social, economic, and environmental problems, which negatively affect the quality of the urban environment. Such a way of extensive urban development can be prevented by turning to the "compact city" concept, based on the most efficient use of internal territorial resources. One of the approaches to optimize processes in the city and stop its territorial extension is the development of urban underground space. This work examines the development of the underground space of the city of Kazan (European Russia), represented by transport infrastructure, as a way to optimize urban areas.