ABSTRACT
Opinions on urban transit network vary the geometric shape, rights of way, tunnel efficiency, and operation strategies, which influence the future scale of urban growth. Major cities cannot function well without tunnels. Studying historical urban transit tunnel operations has revealed a critical topic that has not yet been discussed: how could a through-running tunnel and a regional unified network (RUN) increase both tunnel and transit network efficiency? The article focuses on the comparison of through-running vs. dead-end tunnel operations within the central business district (CBD) and elements of transit network design in the tunnel environment. First, the definition, measures, and decision-making trade-offs are well-interpreted. Second, the time-distance measure shows two independent concepts of static and dynamic transport units on a common variable, allowing tunnel and network designers to precisely define the minimal headway of leading and following trains. The reduced headway decreases the deadhead non-revenue operating time to further increase tunnel efficiency and fleet utilization. Comparative regional rail case studies are presented. Third, schematic station design on platform expansion, track reengineering, and network realignment at the underperforming New York Pennsylvania Station are comprehensively studied. These serial breakdowns enable the establishment of through-running tunnel operation. It is now critical to pay systematic attention to the planning, design, and operation of the interrelation between tunnel efficiency and network throughputs.
