도시철도 노선개편 실행방안 -5, 9호선 직결을 중심으로- = Network Reshuffle for Seoul Metro -Focusing on Direct Link between Line 5 and 9-

다국어 초록 (Multilingual Abstract)

Like most global metropolitan cities, Seoul also faces challenges of oil price and global climate changes. Thus, in the field of transportation, Seoul Metropolitan Government (SMG) has to take a measure to reduce car use and to encourage transit use. Rationalizing metro system is a good candidate for accomplishing this. SMG has fairly good infrastructure of urban railway compared to international competing cities. However, its utilization is not at satisfactory level. Metro stations with the same size of catchment area and similar development intensity do not attract the same number of passengers. On the other hand, several segments of Seoul Metro lines suffered from severe congestion in peak hour every day. This discrepancy is due to a network problem such as irrational line alignment and inconvenient transfer. In 2003, Seoul Development Institute(SDI) proposed a solution to sort out the problem, so called the network reshuffle of Seoul metro. The network reshuffle is characterized by physical connection between different two metro lines and provision of a new direct service across them. It is true that so far, various negative issues with regard to implementing the network reshuffle have been raised from experts in the field of urban railways. This study aims at verifying that the network reshuffle for Seoul metro can be implemented practically. Among several candidate plans of network reshuffle, the direct connection of line 5 and 9 was chosen as a pilot study. Residents in Kangdong area of Seoul, who the pilot study directly affects, are suffering from discrepancy between their trip destinations and metro line`s alignment. While line 5 covering Kandong area is heading for the old center of Seoul, most commuters has their office in Kangnam in the west of Kangdong. Fortunately, a new metro line(line 9) is under construction, which will connect Kandong and Kangnam areas. However, even after provision of line 9 service, commuters from Kangdong to Kangnam will have to go through transfers more than twice. In this context, direct connection of the two lines is essential for enhancing transit utility and reducing car-using commuters. The network reshuffle connecting line 5 and 9 can change the situation that most people in Kangdong area turn down metro as their commuting mode. Three alternatives were established to carry out economic feasibility study for the pilot study. All alternatives include a two-way link connecting line 5 and 9 at Olympic park station. The first alternative assumes that a one-way tunnel is constructed, which links Sangil(or Kildong) to Olympic park. The second alternative installs a short siding at Kangdong station to accommodate newly added trains running from Sangil to Olympic park. The third alternative is the same as the second alternative except it includes a connection to Machon as well. It turned out that the benefit to cost ratio (B/C) exceeded the critical value of 1 for each alternative. The second alternative with the largest value of B/C was chosen to be optimal. There are several technical issues for implementing the optimal alternative. The construction issues arise because it is very hard to make a branch from an metro line operated in an underground tunnel. Construction methods such as diamond wire saw or underpinning make it possible to do that. There are also operational issues of whether newly added trains can be accommodated properly without changes in operation of an existing line. It was found from a fine-tuned train schedule that trains across the two different lines can be operated with 5 minute headway. Besides the above technical issues, there are also institutional or other considerations for implementing the optimal alternative. Master plan of line 9 should be revised, which requires consensus of several parties such as citizen, officials, and experts. In addition, an agency of line 9 operation would indemnify the agency in charge of operation of the existing line 5 for the loss of its revenue. The project can be funded by public finance(PF) or private public partnership(PPP). While PPP is preferred to expedite the construction process, PF has an advantage when stressing a single operation across both metro lines. In conclusion, this study verified that implementing the network reshuffle proposal is both economically and technically feasible. It is strongly suggested that SMG accept the network reshuffle proposal as a future plan for Seoul metro.