  The study of human mobility patterns is of both theoretical and practical
values in many aspects. For long-distance travels, a few research endeavors
have shown that the displacements of human travels follow the power-law
distribution. However, controversies remain in the issue of the scaling law of
human mobility in intra-urban areas. In this work we focus on the mobility
pattern of taxi passengers by examining five datasets of the three
metropolitans of New York, Dalian and Nanjing. Through statistical analysis, we
find that the lognormal distribution with a power-law tail can best approximate
both the displacement and the duration time of taxi trips, as well as the
vacant time of taxicabs, in all the examined cities. The universality of
scaling law of human mobility is subsequently discussed, in accordance with the
data analytics.
