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We
have performed roundabout operational analyses and
feasibility studies for critical intersections
throughout Illinois, Wisconsin, Indiana, and Kentucky.
We utilize RODEL software, the empirically-based
software developed by roundabout expert Barry Crown.
RODEL uses the British method and empirical equations
derived from extensive research. It provides roundabout
capacity, delay, and queuing, for various roundabout geometries.
Paramics microsimulation traffic
modeling software can provide many benefits when
analyzing and designing roundabouts. Paramics simulates
driver behavior on a model of the street network. It
uses gap acceptance theory to determine how a roundabout
will operate. Because Paramics analyzes roundabouts
differently than RODEL, it can be used as a check of the
lane configurations RODEL produces. It is very useful in
modeling closely spaced roundabouts because it can
account for the interaction between them. Paramics is
also excellent for public involvement activities to show
local officials and stakeholders how vehicles will flow
around a proposed roundabout, and to give them a sense
of the roundabout’s footprint and how it will relate to
its surroundings. We feel our experience with modeling
complex and closely spaced roundabouts is unsurpassed,
particularly along highly congested corridors with
multiple three-lane entry approaches.
Paramics operation
modeling helps illustrate roundabout operations to the
public.
ush 41 ramp terminal
intersections study - Green bay, wi
 As
members of a project team, we investigated 52
intersections at 15 interchanges along the USH 41
corridor from Oshkosh to Green Bay, Wisconsin. This
corridor carries up to 90,000 cars per day in some
locations. The study evaluated the feasibility of using
roundabouts as an alternative intersection control at
ramp terminals and adjacent intersections. The study
included collection of field data, functional conceptual
layouts, RODEL operational performance evaluation, and
an alternatives evaluation. The report included
illustrations of design concepts, identification of
property and cost impacts, expected operational
performance, and a decision flowchart.
To aid in
the selection of intersections for conversion to
roundabouts, a set of criteria was developed and applied
to each of the locations. This criteria summarized the
factors necessary for consideration and streamlined the
evaluation.
sth 28 corridor study - sheboygan,
wi - wisdot northeast region
  We
led a study of the STH 28 corridor at the I-43
interchange in Sheboygan, Wisconsin. This is a
four-lane, urban arterial feeding central Sheboygan.
Four very tightly spaced signalized intersections
currently control traffic operations for the corridor.
The corridor is experiencing rapid traffic growth with
nearby vacant land ready for development including the
addition of a Super Walmart southeast of the
interchange. WisDOT is concerned about the long-term
capacity of the signalized system. At
the request of WisDOT, we investigated the feasibility of converting the
intersections to high-capacity roundabouts.
Paramics modeling
of signal versus roundabout control.
 A
detailed preliminary design of five roundabout
configurations was
developed to quantify the impacts of the proposed
project. We used Paramics software to model both the
signalized and roundabout alternatives as individual
systems. For the roundabout alternative, RODEL was used
to calibrate the Paramics model. The two models were
then compared to determine which alternative had
superior traffic capacity. A comprehensive report was
prepared to summarize the comparison of a signalized-
versus roundabout-controlled corridor.
STH 28 Corridor -
preliminary roundabout design.
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