The distribution pattern of the mixed-use indexes is similar to that of the density rates. However, the station areas with a higher mixed-use index are located in the sub-central areas rather than in the CBD area (see Fig. 2b). This means that the station areas in the sub-central area have origin as well as destination functions. The distribution pattern of the mixed-use indexes is better matched with that of the subway riders than of the density rates (see Fig. 2d).