Extend or trim a polyline feature

The Extend or Trim tool extends or trims polyline features to an existing feature boundary. You can edit selected line features or use the tool without a selection and edit features to an inferred boundary. This tool is available in the Modify Features pane.

The following video demonstrates running the tool from the Tools gallery with the tool set to Extend or Trim and to require a selection.

• Video length: 1:00
• This video was created with ArcGIS Pro 3.2.

When you use this tool, consider the following:

• Trimming a selected feature automatically trims the shorter segment. To trim the longer segment, trim without a selection. To edit features without a selection, check the Allow Extend or Trim without a selection check box.
• Extending or trimming a z-aware feature preserves the angular pitch of a modified segment and assigns an interpolated or extrapolated z-value to the new vertex.
• If the selected feature is COGO enabled, you can preserve or update COGO attribute values.

To extend or trim a polyline feature, complete the following steps:

1. Add your data and configure settings for editing.

   Confirm that the feature layer you are editing is editable, the coordinate system assigned to the active map is suitable for the type of edits you're performing, and snapping is configured to help you work efficiently and accurately.

2. On the ribbon, click the Edit tab and click Modify in the Features group.

   Tip:

   To open the Modify Features pane and run the tool in a single step, click the Tools gallery drop-down arrow on the ribbon Edit tab and click Extend or Trim in the Reshape section.

   Running this tool from the Tools gallery uses the tool method and settings last used since the application was opened. If the tool is run for the first time, the default tool method is used. Tool settings such as allowing the tool to run without a selection are saved with the project.

   The Modify Features pane appears.

3. Click Extend or Trim .

   To find the tool, expand Reshape, or type Trim in the Search text box.

   The Select tool automatically runs.

4. Select the polyline features you are extending or trimming.

   To refine the selection in the pane's selection tree, right-click a feature and click Unselect or Only Select This .

5. If the map contains COGO-enabled feature layers, check the Recalculate COGO attributes check box to update COGO values as described in the following table:

   Straight lines	Circular arcs
   Direction is preserved. Distance is recalculated.	Direction is recalculated. Radius is preserved. ArcLength is recalculated.

   Uncheck this setting to preserve existing COGO attribute values.

6. Choose one of the following tool methods:
   • Extend or Trim —Extend or trim polyline features to a shared feature boundary in a single operation. This is the default tool method.
   • Extend —Only extend polyline features.
   • Trim —Only trim polyline features.
7. Hover over the boundary line to which you are extending or trimming the selected features and click the boundary feature when the gray line preview shows the correct edits.

   • Solid line previews extend the feature.
   • Dashed line previews trim the feature.

   Note:

   To extend or trim features without selecting them, check the Allow Extend or Trim without a selection check box at the bottom of the tool pane.

   When this setting is checked, hover over the line feature you are editing and click the preview to extend or trim the feature. If the selected feature is a multipart feature, only the clicked line is edited.

   If the selected feature is a multipart feature, all parts are edited.

8. On the ribbon Edit tab, click Save in the Manage Edits group.