Module%204%20%20The%20Roundabout%20and%20Intersection%20Operations

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Module 4 The Roundabout and Intersection
Operations
Roundabouts in the United States

• How efficiently does a roundabout perform?

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The Goal of Operational Analysis
OR
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Intersection Operations Analysis
PHOTOGRAPHY SOURCE Staff
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What Are the Goals of Intersection Design?
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Delay of Traffic at an Intersection
Geometric Delay
Control Delay
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Signalized Intersection Control
PHOTOGRAPHY SOURCE KAI Staff
In a signalized system, some cars must come to a
complete stop
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Systems that promote smooth flow of traffic are
generally preferred
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Complex Systems Control Flow Through Signalized
Corridors
PHOTOGRAPHY SOURCE KAI Staff
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And signals will always cause some traffic to
stop.
200 AM
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Roundabouts Are Self-regulating.
200 AM
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Roundabouts Operate Using a Gap-acceptance
Process.
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Roundabouts Often Have Less Delay Than Signals
SIGNAL
ROUNDABOUT
Based on MUTCD Warrant 3 (2000 ed.)/Warrant 11
(1988 ed.)
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The Yield-controlled Intersection

Salt Lake City transportation official Tim Harpst
likes the fact that traffic keeps flowing through
roundabouts without a lot of stopping and
starting. They are not air-pollution causing.
And you dont have a traffic signal you have to
maintain. The Salt Lake Tribune, December 26,
2002
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Reducing Delay, Increasing Free Flow
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Geometric Control Right-in, Right-out

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A Roundabout Operates Much the Same Way

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Roundabouts Can Also Be Incorporated into Diamond
Interchanges.
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Roundabout Intersection Operations