Geoscience Reference
In-Depth Information
1 Introduction
Each city lives in motion. Households and
firms create and abandon connections
between them in different roles as economic actors. Some are seemingly random in
appearance, others are predictable. Networks of these connections follow surprising
orders of their distribution in space and time. Flows of different kinds, as a result of
self-organization in city, emerge and die in a rhythm, which we, rather too poeti-
cally, give the name urban heartbeats. Time and space merge within and create a
spatial-temporal phenomenon crucially important in understanding how cities live.
Movements of people, things, or mere information employ many researchers
over generations. Basic aim of their efforts is a functionally better organized city.
Public transportation system may serves us as a useful model of spatial interaction,
multidimensional complex web of links varying in intensity and regularity over
various frequencies, probably most importantly a daily 24-h long.
One of the prominent types of cyclically organized spatial interactions in the city
is commuting between places of housing and places of work. Separation of different
functions has been symptomatic over the whole 20th Century urban planning. The
notion of order and effective organization of daily life in the city was considered
progressive in compare to experienced chaotic mixture of unplanned organic cities.
Bratislava is for decades the biggest and the fastest growing city in Slovakia. We
assume it has the potential to witness such changes.
Without wanting to go in broad discussion concerning positive and negative
sides of modernist urban planning we will remain only concerned with most rel-
evant consequences for urban daily rhythm. Modernist urban plan separating
housing from work and services is responsible for creating demand for transpor-
tation, increasing and decreasing mostly in synchronicity with daily and weekly
economic cycles.
Limiting our attention further it
'
s not really technical details behind commuting
behavior modeling, subject of vast economic and technical literature. Cyclical self-
organization of spatial interaction networks according to our intentions shall be
considered a regularly repeating natural experiment worth attention of researchers.
Each daily cycle in urban life is itself a model of human interaction born and
maturing up to morning peak hour, then easing over midday and once again
growing before daily peak is reached in the late afternoon. Additionally to changing
intensities we also expect asymmetry in speed of variation, probably not inde-
pendent from further qualities and scale.
The public transport network obviously changes over daily and longer cycles.
Connection between different parts of a city is more frequent, possibly also faster in
different hours depending on modes of transportation operating. Weekend and
nighttime rides can be signi
cantly more dif
cult, at least requiring more advanced
planning for minimizing waiting times.
Besides common observations like these, we try to ask a very simple question,
whether topological aspects of complex network of public transportation also sig-
ni
cantly change and what kind of change it is. More precisely, we are interested in
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