module 4 the roundabout and intersection operations how efficiently does a roundabout perform?...
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Module 4
The Roundabout and Intersection Operations
How efficiently does a roundabout perform?
Roundabouts in the United States
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
The Goal of Operational Analysis
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Roundabouts in the United States Module 4 — Roundabout Intersection Operations
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Intersection Operations Analysis
Data Collection
Traffic Volumes
ca p a c i ty G eom etr y
CONTROL
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Turning Movements
Land Use Planning
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
What Are the Goals of Intersection Design?
STOP
STOP
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Delay of Traffic at an Intersection
Control Delay
Geometric Delay
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Signalized Intersection Control
In a signalized system, some cars must come to a complete stop
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Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Systems that promote smooth flow of traffic are generally preferred
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Complex Systems Control Flow Through Signalized Corridors
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Photo: Peter Koonce
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
And signals will always cause some traffic to stop.
2:00 AM
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Roundabouts Are Self-regulating.
2:00 AM
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Roundabouts Operate Using a Gap-acceptance Process.
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Roundabouts Often Have Less Delay Than Signals
Based on MUTCD Warrant 3 (2000 ed.)/Warrant 11 (1988 ed.)
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600 700 800 900 1000 1100 1200 1300 1400 1500Total Major Street Volume (veh/h)
Avera
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Signal (10% left turns)
(50% left turns)
Roundabout (10% left turns)
(50% left turns)
MUTCD Signal Warrant Volume Threshold
SIGNAL
ROUNDABOUT
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
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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 don’t have a traffic signal you have to maintain.”
The Salt Lake Tribune, December 26, 2002
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Reducing Delay, Increasing Free Flow
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Geometric Control: Right-in, Right-out
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
A Roundabout Operates Much the Same Way
Roundabouts in the United States Module 4 — Roundabout Intersection Operations
Roundabouts Can Also Be Incorporated into Diamond Interchanges.
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