Reverse Transition

Used to construct reverse curves between previously drawn elements with an optional tangent length between the two curves. This tool also has the ability to loop the back and or ahead curves.

You can access this tool from the following:

Workflow

1. Click Reverse Transition. The Reverse Transition dialog displays. Any of the inputs can be locked in the dialog at any time. Locking some values may limit or otherwise affect the other values.
2. Select the element to construct the first or ?back? curve from. data point, example, left-click to accept.
3. Select the offset distance from the first element. This can be selected graphically with the mouse or keyed in.

   • Striking the END key will unlock the locked value.

4. Select the second element to construct the reverse transition to. Data point to accept.
5. Select the offset distance from the second element. This can be selected graphically with the mouse or keyed in.
6. Select the Transition information. This information resides in three possible inputs:

   • Linear Transition Length

   • Linear Transition Angle

   • Length

7. Using the left or right arrow keys to toggle between the fields, type in the desired value and press enter to accept.

   

   

   

8. Using the left or right arrow keys toggle to the Back Radius prompt. Define the Back Radius. This can be selected graphically with the mouse or keyed in.

   

9. Select the Ahead Radius or the Radius Ratio information. Using the left or right arrow keys to toggle between the fields, type in the desired value and strike the Enter key to accept.

   

   

   • The Radius Ratio is a direct comparison of the back and ahead radius. For example, if the back radius is set to 100? and the ratio is set to a 1:2, then the ahead radius results in a value of 200?.

10. Data point to select the starting point of the reverse transition.

    

11. Depending on the offsets chosen, select the truncation method. Choose from the following options:

    • None

    • Back

    • Ahead

    • Both

    

    This will truncate or trim the elements used for the construction of the arc. This option is available only when the offset value(s) are set to zero.

12. Optionally for complex loop geometry, if one or both radii are locked, a looping option becomes available.

    

    Looping can be set to the following options:

    • None

    • Back (illustrated above)

    • Ahead

    • Both

Dialog Customization

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

Manipulators

Manipulators are available for:

• Back and Ahead Offsets

• Back Radius

• Ahead Radius

• Length

• Transition Length

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

Properties

Reverse Transition rule data is also accessible in the properties.

Custom Tools

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

• Reverse Curve by Angle - Creates a reverse curve where the two radii are equal and user specifies a deflection angle measured from the first select element, Offsets locked at zero

• Reverse Curve by Radii Ratio - Creates a reverse curve where the second curve radius is a ratio of the first curve radius. Offsets locked at zero

• Reverse Curve by Tangent - Creates a reverse curve where the two radii are equal and you may specify a tangent length between the curves, Offsets locked at zero

• Line at Angle - Creates a simple linear element at a deflection angle measured from the first picked element, Offsets locked at zero