This paper concentrates on the ”real-time” accessibility
in different areas by analyzing the real-time data that are
collected by GPS devices. Our research can be traced to
Real Time Rome Project, which was once exhibited at the
10th International Architecture Exhibition of Venice Biennale
during 2006 [4]. The project was conducted by MIT Senseable
City Lab in corporation with Telecom Italia, ATAC [13] and
other organizations. It was the first time that a large urban area
was covered using a variety of sensing systems, including the
mobile phones and GPS devices in the buses and taxis [12],
[1]. In particular, ATAC, the public transportation authority
in Rome, provided the spato-temporal bus traces which were
collected by the GPS devices located on the buses and sent to
an ATAC server instantaneously. This paper aims at analyzing
this latter dataset to provide a full understanding of dynamic
performance of the public transport network.