Guide for Roundabouts (2023) / Chapter Skim
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Pages 91-100
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6-1 Contents 6-2 6.1 Policy and Legal Considerations 6-2 6.2 Typical ICE Steps 6-3 6.3 Connection to Project Development Process 6-4 6.4 Project Considerations 6-4 6.4.1 Users and Their Needs 6-4 6.4.2 Size and Space Requirements 6-6 6.5 Evaluation of Alternatives 6-6 6.6 Interim and Ultimate Configurations 6-7 6.7 ICE Example 6-7 6.7.1 ICE Step 1 6-8 6.7.2 ICE Step 2 6-10 6.7.3 Summary 6-10 6.8 References This chapter provides a general overview of ICE activities and the relationship to roundabout planning and design. ICE describes an evaluation framework that helps practitioners select a preferred intersection control type (e.g., stop, yield, signal)
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6-2 Guide for Roundabouts 6.1 Policy and Legal Considerations ICE describes an evaluation framework or process that may or may not be associated with an explicit agency policy. Some agencies have implemented policies that establish applicability and legal underpinnings for the process.
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Intersection Control Evaluation 6-3 6.3 Connection to Project Development Process The common ICE steps are compatible with early project planning levels to support state, regional, subarea, or local network planning. Chapter 3: A Performance-Based Planning and Design Approach defines the general stages of the project development process: planning, alternatives identification and evaluation, preliminary design, final design, construction, and maintenance.
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6-4 Guide for Roundabouts 6.4 Project Considerations ICE is based on establishing and objectively screening intersection alternatives that could meet a project's needs. An agency can customize the evaluation process for a given location based on the following: • Project development stage.
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Intersection Control Evaluation 6-5 Intersection footprint, including intersection approach configuration (e.g., raised medians, splitter island presence, driveway access points, turn restrictions) , is a primary ICE consideration.
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6-6 Guide for Roundabouts Such constraints will be dictated by the project site and type. Reconstructing intersections and retrofitting an existing circular intersection may present more constraints than new construction.
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Intersection Control Evaluation 6-7 6.7 ICE Example This section provides an ICE example, from a Step 1 intersection screening assessment that validates roundabout feasibility through a Step 2 detailed analysis to refine and customize the recommended roundabout alternative to site conditions. The study location (Intersection 1)
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6-8 Guide for Roundabouts • Alternative 2a: Roundabout at Intersection 1, roundabout at Intersection 2. • Alternative 2b: Five-leg roundabout consolidating the two intersections.
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Intersection Control Evaluation 6-9 (a)
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6-10 Guide for Roundabouts conflicts (Exhibit 6.4c)
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