If the intersection definition is out-of-date, 
is displayed next to the intersection in the Prospector tree. This indicates that the corridor regions in the intersection need to be updated. You can update corridor regions in an intersection manually, or you can specify that the intersection object update corridor regions automatically.
When you update corridor regions in an intersection, any manual edits that were made to the regions or targets within the intersection corridor are lost.
To automatically update the corridor regions in an intersection
- In Toolspace, on the Prospector tab, expand the Intersections collection. Right-click the intersection. Click Update Regions Automatically . Note: When you toggle this option on, if Autodesk Civil 3D detects that changes have been made to the intersection that require the corridor regions to be updated, then the update occurs immediately when you toggle the option on.
To manually update the corridor regions in an intersection
- In Toolspace, on the Prospector tab, expand the Intersections collection. Right-click the intersection. Click .
When the Update Regions and Rebuild Corridor command is invoked, the corridor region stations in the intersection are updated in order to stay in synchronization with the intersection area geometry. The corridor properties are updated to reflect these new region station values.