Underground transport: An overview

Transport systems play an essential role in urban, economic and social development. Utilising underground space for transport is a continuing trend across the globe during past decades. Underground transport systems have been chosen by cities as potential solutions for solving urbanisation problems such as traffic congestion, land shortage, and noise and air pollution. This paper provides an overview of five main forms of underground transport: underground railway systems, underground car parks, urban underground roads and expressways, underground freight transport systems and underground pedestrian systems. In each case the overview explores their origins, development, advantages and challenges, as well as other research foci. The paper then discusses key policy challenges for underground transport systems and provides recommendations for future research.