The Norsborg Metro Depot - Case Study of a Modern Urban Development in Stockholm

"Construction of large facilities underground in urban areas has many advantages. In order to show the advantages, a case study of the Norsborg metro depot in Stockholm Sweden has been made. The Norsborg metro depot will be the largest and most modern underground metro depot in northern Europe. The depot has been built in hard rock in an urban area with small impact on the environment and local residents. The paper describes how it is possible to build underground facilities in a cost efficient way and take care of the challenges regarding working environment that comes with locating a permanent working place underground. INTRODUCTION The Stockholm area is one of the five fastest growing regions in Europe and home to more than a fifth of Sweden's population on just two percent of Sweden's surface. The population is growing rapidly, with about 35,000 people per year and is expected to reach 2.6 million in 2030. In order to meet the development and enable continued growth, housing projects and expansion of infrastructure need to keep the same pace; this is an easy conclusion to make but much more difficult to realize in practice. The main challenge is to accomplish development in a sustainable and efficient manner, minimizing the use of resources and land. By constructing facilities underground more urban space will be made available for development and/or for greening of city centers. Considering sustainability factors such as land value in decision making for placing of structures or facilities, underground locations could become a first choice alternative. During 2015 and 2016, several major underground infrastructure projects in the city of Stockholm will start, including a 14 km sewage tunnel and an 18 km by-pass highway tunnel. Furthermore the Stockholm metro system is currently undergoing the largest expansion since the 1970’s, a 19 kilometers extension of the metro system including new trains and new stations is planned. During 2013 - 2015 Skanska Sweden took part in the construction of a new metro depot placed underground in the southern part of Stockholm; the Norsborg metro depot. This is a top modern urban underground facility that in 2017 will serve as depot for 17 new metro trains. The project was selected for “Outstanding Project of The Year” at the ITA Tunneling Awards 2015."