Private financiers of Line 9 also used the conservative ridership estimates to cut costs wherever they can. Line 9 was already proving more expensive to construct than its predecessors for its inclusion of express service with extra tracks and rail equipment, and acquisition of the most expensive land in Seoul, according to Donga Weekly.18 The underestimated ridership predictions gave the financiers green light to reduce its rolling stock size from the original 186 cars (31 6-car trains) to 144 cars (36 4-car trains). As the other eight Seoul Metro lines operated 8-car trains, Line 9 began by running exclusively 4-car trains.