This study aims to find out the effects of a suburban railway investment on population change. Based on this quest, we hypothesize that reliable and fast rail transit service, which connects main destinations in an urban region has a significant role in population increase nearby its stations. In this vein, we use IZBAN Suburban rail as fast rail transit service in Izmir urban region as case study. Accordingly, population changes between 2013 and 2018 in the neighborhoods, where there is direct access to IZBAN stations, are examined in relation to other neighborhoods by Analysis of Covariance (ANCOVA) statistical models. Two model groups are devised in the study. Basic Models examine the impact of IZBAN Neighborhoods considering Izmir sub-regions, i.e., North, Metropolitan Area and South Sub-Region, while Expanded Models estimate interaction variables to account for spatial variation in population changes. We find significant relative increase in the populations of non-metropolitan neighbourhoods served by IZBAN stations. There is high variation between different sub-regions and IZBAN sections. Population increase is higher in the Northern and Southern sub-regions, which leads us to reach IZBAN-induced decentralization in the metropolitan area. Although, IZBAN exemplify an incipient transit-oriented development in Turkey, it falls short of its counterparts in the world. Strategic planning decisions are needed to support transit-oriented development around IZBAN stations.