Urban Heartbeats (Daily Cycle of Public Transport Intensity) - Geoinformatics for Intelligent Transportation - page 199

Zemanov et al. [ 32 ] found that the network of cortical area displays clustered

synchronization behavior and the dynamical clusters closely coincide with the
topological community structures observed in the anatomical network.
A useful study was elaborated by Wu et al. [ 33 ] and it can be used not only in
medicine, but also in public transport analyses. The main objective of this study was
to reveal an overlapping community structure of the structural brain network in
individuals. They demonstrated that 90 brain regions were organized into 5 over-
lapping communities associated with several well-known brain systems. The
overlapped nodes were mainly attributed to brain regions with higher node degrees
and nodal ef

á

flow of information through the
structural brain network. Similar overlapped nodes exist in communities of public
transport network. These nodes (stops) represent the most important places of the
public transport network.
There could be also found some parallels between brain network and trans-
portation network research in the recent paper of Crossley et al. [ 34 ] which
examines community structure of the human brain. They revealed modi

ciency and played a pivotal role in the fl

cations in
network structure of dynamic brain network through changes in communities.

2 A Representative Day in Bratislava

We have made first analysis of Bratislava public transport network in our previous

paper [ 35 ]. Since much information remains hidden in a static network represen-
tation, we decided to further elaborate research on the role of time. Data analyzed in
this paper are more detailed in respect of temporal dimension. Thus, the analysis is
based on the dynamics throughout the day. In our assumption, the nature of public
transport changes during day, along with changing demand of its users. This is
where our research potentially connects with economic literature.
We obtain detailed time schedules of public network in Bratislava used for
iTransit Android client by Apptives. Reference date for the schedule is July 09,
2013, but it consists of alternative daily schedules for ordinary workday, weekend
day, and school vacations workday. We proceed by pooling these different
schedules into a representative day not existing in reality, but useful as an analytical
generalization.
The network under study consists of 584 stations represented as 1,379 station
nodes according to their geographical position and total of 94 routes. Because each
station node is operated only in one direction, we used directed graph as repre-
sentation of network. By connecting stations with all routes regardless of vehicle
type, we got 1,536 links served by public network. Only some links are operated
throughout the whole day. During 24 h cycle we record 463,125 one station rides.
For a better comparison, we have split the 24-h day into equal-length samples.
Ranges of individual intervals are shown in Table 1 .