Examples of benefits of underground urban public transportation systems

Abstract As the world's population has increased, particularly in urban centers, cities have turned increasingly frequently to underground transportation systems to help solve problems of traffic congestion, noise and air pollution, and densely built-up urban areas. This report briefly considers the issues involved in planning an urban underground traneportation system, and then presents examples of such systems now in operation in ten different countries. These countries have used a wide variety of approaches and methods in making decisions regarding the planning and construction of underground transportation systems. Also include is an appendix describing cost-benefit studies concerning proposed transportation tunnels in the United Kingdom.