To Insert RailMainTrackSiding Subassembly into an Assembly 

1. Click "Home" tab
2. Open "Tool Palettes" that you want to copy the subassemblies into. You may open an existing tool palette or create a new one.
3. Right-Click "Tool Palettes" title bar and Select "Import Subassemblies" from the context menu.
4. In the "Import Subassemblies" dialog box, click the browse button in "Source File:", and browse to the location of RailMainTrackAndSiding.pkt file and select it.
5. Clear the check box of "Link Directly to .PKT Files"
6. In the "Import To" section, select "Tool Palette", and then select the desired tool palette in the drop-down list.
7. Optionally select the "Catalog Library/My Imported Tools" check box to add the subassemblies to the My Imported Tools catalog in the Content Browser. 
8. Click OK.
9. Open "Tool Palettes" that RailMainTrackSiding Subassembly has been imported.
10. In the Tool Palettes window, find and click the RailMainTrackSiding subassembly.
11. Click on the assembly. The RailMainTrackSiding Subassembly is inserted onto the assembly.
12. Click the inserted RailMainTrackSiding subassembly, Right-Click and select "Subassembly Properties..." on Context Menus.
13. In the Properties dialog box, change the Information, Parameters and Codes.

For more information, refer to: The Subassemblies section of the Autodesk Civil 3D Help.

Installation:

1. Download SetupRailSubassembly1.msi from Autodesk App Store.
2. Double-Click SetupRailSubassembly1.msi file to install RailMainTrackAndSiding.pkt in a location you specified.

Uninstallation:

To uninstall this plug-in, click Control Panel > Programs > Programs and Features (Windows 10/11) and uninstall as you would any other application from your system.