A field experiment in Yokohama (Japan) revealed that a macroscopic fundamental
diagram (MFD) linking space-mean flow , density and speed exists on a large urban area.
Despite these and other recent findings for the existence of well defined MFDs for urban
areas, these MFDs should not be universally expected. In this thesis, the properties of
a well defined MFD are investigated and it is found out that the spatial distribution of
density/occupancy in the network is one of the key components that affect the scatter
of an MFD and its shape. An analytical derivation of the spatial distribution that
considers correlation between adjacent links has also been proposed. The scatter of
an MFD in terms of errors in probability density function of spatial occupancy and
errors of individual links' fundamental diagram (FD) have also been investigated and
an analytical estimation of the errors is provided. Using real data from detectors for
an urban arterial and a freeway network we validate the proposed derivations and we
show that an MFD is not well defined in freeway networks as hysteresis effects are
present. The hysteresis phenomenon in network is investigated at different levels of the
network and it is found out that the heterogeneity of the network and the hysteresis
in the individual detectors should account for this phenomenon. The datasets in this
paper consist of flow and occupancy measures from 500 fixed sensors in the Yokohama
downtown area and 600 loop detectors in the Twin Cities Metropolitan Area Freeway
network (Minnesota, USA).
University of Minnesota Master of Science thesis. September 2009. Major: Civil Engineering. Advisor: Nikolas Geroliminis. 1 computer file (PDF); viii, 61 pages.
Investigating the Properties and Existence of a Macroscopic Fundamental Diagram for Arterial and Freeway Traffic Systems.
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