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Corey Johnson-Bentley

Intersection Design with Roadway Designer

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Objectives

Preliminary Design Surfaces

Radius Return Creation

Defining Point Controls/Secondary

Alignments

Final Design Surface Creation

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Starting InRoads/Geopak

• Start InRoads or Geopak

• Load the files for this Lesson

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Preliminary Design

• Two Corridors have been created

– CL-278 (Main Roadway)– Reloc-2 278 (Side Road)

• CL-278 has Style Constraint for Widening

• Reloc-2 278 has Point Control for Right Turn Lane widening

• Both Corridors have Superelevation Defined

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Create Surfaces

• Analyze the PreliminaryCorridors

• Create PreliminaryDesign Surfaces

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Multi-Center Curve Command• Creates both Horizontal and

Vertical Curves based on two alignments

• One, Two or Three Center Curves can be created

• Vertical Curves are created that match the instantaneous longitudinal grade at PVC and PVT

• Vertical Geometry Options– Vertical Distance– Gradient– Surface (Useful when the cross

slope varies ie. Superelevation)

• Always Review the Results and make adjustments if necessary

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Create Radius Geometry

• Create Radius returns for NW and SW Quadrant of Intersection

• Review the Results with the Geometry and Profile Commands

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Point Controls and Secondary Alignments

• Used to Modify the Behavior of Template Points

• Overrides Existing Point Constraints

• Priority can be used to resolve conflicting point controls

• Secondary Alignments control the direction of cross section processing

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Modeling the Side Road

• Assign Radius ReturnAlignments as Point Controls

• Increase the template drop interval at PC

• Generate Design Surface for Reloc-2 278– Enable Add Transverse

Features

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Modeling the Main Line

• Assign Radius Return Alignments as Point Controls for the main line

• Increase the template drop interval

• Add/Edit template drop for intersection

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Create the Finished Surface

• Create One Surface from Multiple Corridors

• Review the Results

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Other Techniques for Intersections

• Targeting Design Surface Features

• Parent/Child Components

• End Condition Exceptions

• Other Possible tools to consider– Corridor Clipping– Target Aliasing

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Skewed Intersections• Change the active

corridor

• Use Parent/Child Components and End Condition Exceptions for another intersection

• Create Surface for Side Roads

• Use transverse feature from Side Road surface as a point control for the main line

• Process and generate one surface from all three corridors

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Summary and Review

You are now able to…

Before continuing let’sreinforce what

you have learned!