Subway network expansion and transit equity: A case study of Gwangju metropolitan area, South Korea

Public transit systems enable metropolitan areas to develop and be sustained by providing mobility to people. At the same time, they can function as tools to alleviate the social and spatial exclusion of deprived groups or communities. Recently, equity has become a crucial element in transportation planning, yet it has not received sufficient attention. This study examined transit equity and the changes in it resulting from a major expansion of the transit network in a metropolitan area. Three stages of transit service provision were defined based on the actual network expansion plans. Transit equity at the global level was measured using the concept of the Gini index. The resultant Gini indices indicated that transit equality has improved and will continue to improve with the provision of additional subway lines. This was followed by a statistical analysis to determine which groups or areas were more likely to benefit from the expansion. When only a linear subway line was added to the bus network, transit dependent groups did not appear to benefit from the increased transit supply. However, with the addition of another circular subway line, females and young people were found to have a significant and positive association with the increased transit supply, indicating a vertically fairer distribution of resources.