Use this dialog box to specify details for the approach roads that are connected to the roundabout.
This dialog box is the second in a series of four dialog boxes that step you through creating a roundabout.
Approach Road Alignments Selected
The number of approach road alignments that are currently selected for creating this roundabout is displayed at the top of this dialog box.
- Previous\Next
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Use these buttons to scroll through and specify parameters for each of the approach roads included in this roundabout. If you want to apply the same parameters to all of the approach roads in the roundabout, use the Apply To All button. If you want to apply different parameters for the approach roads, do not use the Apply To All button.
The approach road alignments are named using a naming convention that identifies the direction of the base alignment that was selected; for example, an “East to west approach” road contains “EW” in the approach road alignment name (Approach_EW_).
- Apply to All
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Clicking this button applies the parameters that are currently specified on this dialog box to all of the approach roads included in this roundabout.
Predefined Parameters To Import
You can select a set of parameters from the dropdown list. As soon as you select a set of parameters, the Approach Road Parameters are updated with the selected values. If desired, you can change the value of any parameter.
To add a new set of parameters to the list, click 
. The Preset - Add dialog box is displayed.
Enter a preset name for the new set of parameters, and then enter the values for all parameters. If you want to edit existing sets of predefined parameters, select the preset that you want to edit from the list of presets and click 
. To erase an existing set of predefined parameters, select the preset that you want to erase from the list of presets and click 
.
Default Connecting Radius
This radius is used in cases where the existing alignment does not run through the center of a roundabout. In this case, an arc with that radius is inserted in a way that the central alignment runs directly to the center of the roundabout. If the radius you chose does not fit the geometry, then the smallest radius possible is used to satisfy the standard.
Approach Road Parameters
These parameters specify the geometry of the approach roads in the roundabout.
Hovering the cursor over these controls displays a conceptual illustration of the component or geometry specified by that control on the right side of this dialog box.
- Exit Road Width
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When the US_Imperial roundabout standard is selected, the exit road width is measured from the pavement marking.
When the French (SETRA) standard is selected, the exit road width is the width of the diverging taper at the beginning of the exit radius.
- Exit Radius
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This parameter specifies the radius at the point where the left approach edge connects to the roundabout.
- Exit Connecting Radius
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When the French (SETRA) roundabout drawing standard is selected, this parameter specifies the radius at the beginning of the approach. With this arc, the left approach edge is connected to the existing road.
- Diverging Taper Tip Width
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When the French (SETRA) roundabout drawing standard is selected, this parameter specifies the width of the diverging taper at the end of the exit connecting radius.
- Exit Flare Length
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Specifies the length of the flare at the exit.
- Exit Flare Type
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When the US_Imperial roundabout drawing standard is selected, this parameter specifies the flare type used at the exit. You can choose arc or line flare type.
- Road Width At Departure
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When the US_Imperial roundabout drawing standard is selected, this parameter specifies the width of the diverging taper at the beginning of the flare.
When the French (SETRA) roundabout drawing standard is selected, this parameter specifies the width of the diverging taper at the end of the exit connecting radius.
- Entry Road Width
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Specifies the entry road width, measured from the pavement marking.
- Entry Radius
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Specifies the radius at the point where the right approach edge connects to the roundabout.
- Entry Flare Length
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Specifies the length of flare at entry.
- Entry Flare Type
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Specifies the type of flare used at the entry. You can choose arc or line flare type.
- Road Width At Approach
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Specifies the width of the merging taper at the beginning of the flare.
Alignment Style
Specifies the alignment style from the list of styles available in the drawing.
Alignment Layer
Specifies the alignment layer from the list of layers available in the drawing.
Alignment Name Prefix
Displays the name of the alignment used to specify the central approach road. This name is used as a prefix for the alignments that are generated by the roundabout creation. For the right edge alignment, the suffix “_EDGE_RIGHT” will be added to the alignment name. For the left edge alignment, the suffix “_EDGE_LEFT” will be added to this name.
Alignment Label Set
Specifies the alignment label set from the list of label sets available in the drawing.