Used to construct an arc between two previously place elements.

You can access this tool from the following:

Arc between Elements constructs an arc between two previously placed elements. This tool has the ability to optionally apply a back and/or forward transition and/or taper between the elements and the constructed arc.

Workflow

1. Select the element to construct the line from. Data point, example, left-click to accept.

   

2. Set the offset distance from the first element. This can be selected graphically with the mouse or keyed in.

   

3. Select the second element to which the arc will extend. Data point to accept.

4. Set the offset distance from the second element. This can be selected graphically with the mouse or keyed in.

5. Another option is to Populate the Back Taper information. This information can reside in three formats:

   • Length - Ratio (Shown Below)

   • Length - Offset

   • Ratio - Offset

   Using the left or right arrow keys to toggle between the fields, type in the desired value and strike the Enter key to accept.

   
   
   Note: If the Back Taper option is set to None in the dialog, you will not be prompted for this information.

6. Another option is to Populate the Ahead Taper information. This information can reside in three formats:

   • Length - Ratio (Shown Below)

   • Length - Offset

   • Ratio - Offset

   Using the left or right arrow keys to toggle between the fields, type in the desired value and strike the Enter key to accept.

   Note: If the Ahead Taper option is set to None in the dialog, you will not be prompted for this information.

7. Another option is to populate the Back Transition information. This information can reside in eight possible format combinations:

   • Spiral - Length (Shown Below)

   • Spiral - A-Value

   • Spiral - Deflection

   • Spiral - Delta R

   • Spiral - RL

   • Curve - Length

   • Curve - Deflection

   • Curve - Delta R

   Using the left or right arrow keys to toggle between the fields, type in the desired value and strike the Enter key to accept.

   Note: If the Back Transition option is set to None in the dialog, you will not be prompted for this information.

   Spiral Definitions:

   • Length = Length of spiral

   • A value = Square root of RL

   • RL = Radius multiplied by the length

   • Deflection = The deflection at the spiral PI (sometimes called spiral angle in the United States)

   • Delta R = The offset from where the simple curve would be without a spiral to the curve with a spiral (called throw or offset in the United States)

8. Optional, populate the Ahead Transition information. This information can reside in eight possible format combinations:

   • Spiral - Length (Shown Below)

   • Spiral - A-Value

   • Spiral - Deflection

   • Spiral - Delta R

   • Spiral - RL

   • Curve - Length

   • Curve - Deflection

   • Curve - Delta R

   Using the left or right arrow keys to toggle between the fields, type in the desired value and strike the Enter key to accept.

   Note: If the Ahead Transition option is set to None in the dialog, you will not be prompted for this information.
9. Select the radius of the arc. This may be chosen graphically or keyed in directly.

10. Select the truncation method. Choose from the following:

    • None

    • Back

    • Ahead

    • Both

    This will truncate or trim the elements used for the construction of the arc.

Use of ALT Key

During the operation of the command, hold down ALT key to switch between alternate solutions. For this command, there are two functions for the key:

• When picking base elements, pressing ALT allows you to pick components of complex elements instead of the complex itself.

• When placing the arc, pressing ALT switches between minor arc and major arc (loop solution).

Curve Transitions

The curve construction made from this tool can include a transition between the selected reference element and the curve. The transition options available are:

• None - No transition (only the central simple curve is constructed)

• Spiral - A Spiral (curve construction is created)

Values that can be used to create the spiral are listed here.

• Double Spiral - Use this tool to create two spirals; the first of which transitions in same hand as a reference element starting at the reference element radius and transitioning to infinity. The second spiral transition from infinity to the radius of the new curve and is opposite hand. Although this curved reference element is the most common use case, a double spiral can be used anywhere that is needed.

• Curve - Constructs a 2 center curve (the transition curve is defined by radius and length)

• Arc Ratio - Constructs a 2 center curve (the transition length is defined by a ratio of the central curve)

Dialog Customization

Right-click on the dialog to customize the dialog for specific tasks or user preferences.

Manipulators

Manipulators are available for:

• Offsets

• Back Taper

• Ahead Taper

• Back Transition

• Ahead Transition

• Radius

• Drag handles to dynamically adjust the optional offset distances from both arcs

Properties

Arc between Elements rule data is also shown in the properties on the Element Information dialog.

Custom Tools

These pre-customized versions provide a simplified prompt sequence for many common construction tools. Right-click on the Arc between Elements icon then choose Show/Hide Arc from Element Tools to access the following options:

• Simple Arc - Creates a radius arc without spirals or tapers at both ends, Offsets locked at zero

• Spiral-Arc-Spiral - Creates a radius arc with spiral transitions but no tapers at both endsl, Offsets locked at zero

• Taper Arc Taper - Creates a radius arc with tapers but no transitions at both ends, Offsets locked at zero

• 3 Center Arc - Creates a radius arc with radius transitions at both ends, result is a three centered curve, Offsets locked at zero

• 2 Center Arc - Creates a radius arc with radius transitions at one end, result is a two centered curve, Offsets locked at zero