Abstract

Repeated excavations of buried utilities cause road congestion and maintenance conflicts. Besides, the interference of buried utilities in limited underground spaces does not meet the requirement of sustainable urban underground development. Multi-purpose utility tunnels (MUTs) integrate all utilities together in one tunnel and can be accessed by humans. MUTs reduce the excavation needs and costs and avoid the traffic congestion caused by excavations. MUTs also provide easy access for inspection and maintenance of all types of utilities inside the tunnel. MUTs have been in existence since the 19th century. MUTs in Europe and Japan were developed rapidly especially during the period 1961 to 2000. However, the development of new tunnels in recent years is limited and lacks long-term planning. MUT projects in North America are mainly in university campuses. On the other hand, China is making a big progress in MUT planning and construction because the Chinese government is taking MUT construction as an important urban infrastructure development. Focusing on China, the experience of MUT planning, construction and management in China can be very useful for other countries to examine the potential of MUTs as a sustainable option for future municipal asset rehabilitation projects. MUT planning is a key factor of urban underground space planning, which is an important part of urban planning. Previous research focused on MUT technologies; however, few researches focused on MUT planning. Location selection for MUTs is an important phase for MUT planning and it is complicated because it depends on several criteria, such as traffic volume and the density of the utilities. This research provides a general method for MUT location selection at different urban scales (e.g. street, district, borough) using Geographic Information System (GIS) spatial analysis. Multi-criteria decision making (MCDM) is used in this research to select potential MUT locations. The weights of the criteria are calculated using the Analytic Hierarchy Process (AHP) method. Several cases studies are used to demonstrate the feasibility of the proposed method. The specific objectives of the research are: (1) Review the history and recent development of MUTs in the world; (2) Carry out a cost analysis based on the project information to find out the relationship between cost and MUT cross section dimension, etc.; (3) Provide a general method for MUT location selection based on GIS spatial analysis.
The conclusions of this research are as follows: (1) The experience of MUT planning and construction in Asia especially in China provides an alternative method for underground utilities, and is very useful for other countries to examine the feasibility of applying MUTs for future municipal asset rehabilitation projects. (2) Based on the AHP results, among the eight criteria used in the questionnaire, the most important criteria for MUT location selection are Annual Average Daily Traffic, utility density, expected number of excavations and future underground development projects. (3) The general method to select potential MUT locations using GIS spatial analysis is feasible.