How To: Modify the length of two connected polylines
Instructions provided describe how to edit two line features in the same feature class or shapefile, at the same time, that share a common end point.
For example, segment A is 100 ft long, and segment B is 100 ft long. The end node of A is coincident with the start node of B. To extend A to 10 ft longer without overlapping B, follow the procedure below to make A 110 ft and B 90 ft.
Before following the steps below, have two polyline features in the same feature class or shapefile that have a node that is coincident.
In ArcMap, View > Toolbars, turn the Editor and Topology toolbars on.
On the Topology toolbar, click the Map Topology icon.
In the Map Topology dialog box, select the polyline layer. Keep the default tolerance and click OK.
On the Editor toolbar, click the Editor drop-down and select Start Editing.
On the Editor toolbar, set the task to Modify Feature and the target to the polyline feature class or shapefile.
On the Editor toolbar, click the Edit tool. Click on one of the two line features to select it. Make a note where the segments approximately meet.
Click a blank space on the map with the Edit tool to deselect the line.
On the Topology toolbar, click the Topology Edit tool.
While holding down the 'N' key, draw a box around the commonly placed node between the two lines. Only the node should select in a pink color. Let go of the 'N' key.
While holding down the 'S' key, click and drag the selected node. The node can be moved by dragging it. If the X,Y destination is known, right-click > Move To, and enter the X,Y values.
On the Editor toolbar, click Save Edits and Stop Editing.