You can specify a new assembly to use in an existing corridor region. When a corridor region assembly is changed, targets are maintained if: 
- The new assembly has the same subassembly types as the original assembly. 
 
- The left and right sides of the new assembly are identical to the original assembly. 
 
 To change a corridor region assembly by dragging an assembly from a Tool Palette or catalog into the into Section Editor 
- In Toolspace, on the Prospector tab, expand the Corridors collection. Select the corridor. Right-click. Click Corridor Section Editor. 
 
- On the Section Editor Ribbon
Station Selection panel, select a station that is in the region you want to change. In the Select a Station list, 
 indicates that a station is associated with a region. 
  
- In a Tool Palette or catalog, select an assembly. Click and drag the assembly onto the assembly in the Section Editor. 
A preview of the assembly is displayed in Section Editor. In Prospector, 
 appears next to the preview assembly. 
 Note: If the new assembly uses the same subassembly types as the original assembly, then the targets are maintained. 
  
- To modify targets, click Section Editor tab
Preview panel

Edit Preview Targets.  
- In the Target Mapping dialog box, set the surface, offset, and elevation targets in the corresponding Object Name fields. 
 
- Click OK to close the Target Mapping dialog box. 
 
- Click Section Editor tab
Preview panel
Apply. Note: Cancel discards the preview assembly. 
 The corridor is rebuilt using the new assembly in the specified region. 
  
 
To change a corridor region assembly using the Section Editor ribbon
- In Toolspace, on the Prospector tab, expand the Corridors collection. Select the corridor. Right-click. Click Corridor Section Editor. 
 
- On the Section Editor Ribbon
Station Selection panel, select a station that is in the region you want to change. In the Select a Station list, 
 indicates that a station is associated with a region. 
  
- Click Section Editor tab
Corridor Edit Tools panel
Change Assembly.  
- In the Change Assembly dialog box, either select an assembly from the list, or click 
 to pick an assembly from model space. A preview of the selected assembly is displayed in the Change Assembly dialog box. 
 Note: If the new assembly uses the same subassembly types as the original assembly, then the targets are maintained. 
  
- Click OK. 
The corridor is rebuilt using the new assembly in the specified region. 
  
 
To change a corridor region assembly by selecting an assembly from Prospector
- In Toolspace, on the Prospector tab, expand the Corridors collection. Select the corridor. Right-click. Click Corridor Section Editor. 
 
- On the Section Editor Ribbon
Station Selection panel, select a station that is in the region you want to change. In the Select a Station list, 
 indicates that a station is associated with a region. 
  
-  In Toolspace, on the Prospector tab, expand the Assemblies collection. Select the assembly. Right-click. Click Preview in Section Editor. 
A preview of the assembly is displayed in Section Editor. In Prospector, 
 appears next to the preview assembly. 
 Note: If the new assembly uses the same subassembly types as the original assembly, then the targets are maintained. 
  
- To modify targets, click Section Editor tab
Preview panel

Edit Preview Targets.  
- In the Target Mapping dialog box, set the surface, offset, and elevation targets in the corresponding Object Name fields. 
 
- Click OK to close the Target Mapping dialog box. 
 
- Click Section Editor tab
Preview panel
Apply. Note: Cancel discards the preview assembly. 
 The corridor is rebuilt using the new assembly in the specified region.