Module 4 The Roundabout and Intersection Operations How efficiently does a roundabout perform? Roundabouts in the United States

Module 4 — Roundabout Intersection Operations The Goal of Operational Analysis OR PHOTOGRAPHY SOURCE: WSDOT—Brian Walsh

Roundabouts in the United States Module 4 — Roundabout Intersection Operations Intersection Operations Analysis Data Collection Traffic Volumes PHOTOGRAPHY SOURCE: Staff Turning Movements Land Use Planning

Roundabouts in the United States Module 4 — Roundabout Intersection Operations What Are the Goals of Intersection Design?

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 PHOTOGRAPHY SOURCE: KAI Staff

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 PHOTOGRAPHY SOURCE: KAI Staff 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.) SIGNAL ROUNDABOUT

Roundabouts in the United States Module 4 — Roundabout Intersection Operations PHOTOGRAPHY SOURCE: Lee Rodegerdts 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. PHOTOGRAPHY SOURCE: Lee Rodegerdts

Roundabouts in the United States Module 4 — Roundabout Intersection Operations Roundabout Intersection Operations PHOTOGRAPHY SOURCE: Lee Rodegerdts PHOTOGRAPHY SOURCE: Paul Ryus