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Temporal variations in daily traffic flow profiles on urban access-controlled roadways
xiii, 283 leaves : illustrations ; 28 cm.
The proper evaluation of transportation improvements requires
the estimation of daily traffic flow profiles. This research
investigated the temporal variations of daily traffic flow
profiles on urban access-controlled roadways. A daily
traffic flow profile modeling procedure was developed.
Hourly traffic flow data and study site characteristics were
obtained for 42 locations in Texas. This information was
gathered for as many years as possible between 1969 and 1995
and daily traffic flow profiles were calculated. The study
site characteristics of interest included: annual average
daily traffic (AADT) per lane, county population, roadway
orientation, and location. Daily traffic flow profiles on
urban access-controlled roadways typically have four
intervals. The consistent definition of these intervals
allows their attributes to be modeled. Twelve straight-line
approximations of each daily traffic flow profile were
completed. The best-fit approximation approach defined peak
period attributes with the hours that had volumes within 25
percent of their most appropriate peak-hour volume.
Transitions between the peak and off-peak periods were one or
two hours wide. The defining attributes of the straight-line
approximations were modeled. AADT per lane was the focus of
these models. Peak-period durations were modeled with
respect to AADT per lane, and the morning peak-period start
hour and evening peak-period end hour were based on peak-
period duration. Interval magnitudes were related to
interval duration or the database average. A seven-step
procedure was developed that combined the model results for
an estimation of daily traffic flow profiles. The validity
of the profile attribute models was tested. It was found
that the majority of the models estimated their straight-line
approximation counterparts relatively well. Most of the
average interval durations and magnitudes were not
significantly different than those originally approximated.
The results of the proposed approach were compared to those
of the current profile approximation methodology and the
calculated daily traffic flow profiles at 15 validation study
sites. The current approach approximated daily traffic flow
profiles more accurately than the proposed approach. The
gross nature of the straight-line process within the proposed
approach overwhelms the advantages it offers and the
estimation abilities of the individual profile attribute
Issued also on microfiche from University Microfilms Inc.
Includes bibliographical references: pages 147-149.