  Mobility of economically underprivileged residents in China has seldom been
well profiled due to privacy issue and the characteristics of Chinese over
poverty. In this paper, we identify and characterize underprivileged residents
in Beijing using ubiquitous public transport smartcard transactions in 2008 and
2010, respectively. We regard these frequent bus/metro riders (FRs) in China,
especially in Beijing, as economically underprivileged residents. Our argument
is tested against (1) the household travel survey in 2010, (2) a small-scale
survey in 2012, as well as (3) our interviews with local residents in Beijing.
Cardholders' job and residence locations are identified using Smart Card Data
(SCD) in 2008 and 2010. Our analysis is restricted to cardholders that use the
same cards in both years. We then classify all identified FRs into 20 groups by
residence changes (change, no change), workplace changes (change, no change,
finding a job, losing a job, and all-time employed) during 2008-2010 and
housing place in 2010 (within the fourth ring road or not). The underprivileged
degree of each FR is then evaluated using the 2014 SCD. To the best of our
knowledge, this is one of the first studies for understanding long- or mid-term
urban dynamics using immediate "big data", and also for profiling
underprivileged residents in Beijing in a fine-scale.
