This topic describes the behavior of certain features when a drawing is worked with in AutoCAD Civil 3D 2015 and in prior versions of AutoCAD Civil 3D. It also describes the behavior of subassemblies in relation to different versions of Autodesk Subassembly Composer or different versions of AutoCAD Civil 3D.
The new assembly frequency settings available in the Frequency To Apply Assemblies dialog box will not be retained if the drawing is opened in a prior version of AutoCAD Civil 3D. When the corridor is rebuilt in a prior version, stations will no longer be applied adjacent to the start and end of offset targets, along offset target curves, or along baseline curves (using the By Curvature setting).
If you save the drawing in a prior version of AutoCAD Civil 3D without any changes and reopen it in AutoCAD Civil 3D 2015, the assembly frequency settings are restored to their previous settings.
The new Section setting available on the Profile tab of the Projection Style dialog box will not be retained if the drawing is opened in a prior version of AutoCAD Civil 3D.
If you save the drawing in a prior version of AutoCAD Civil 3D without any changes and reopen it in AutoCAD Civil 3D 2015, the projected solids are restored to their previous settings. If you edit the alignment or the projected solids in a prior version of AutoCAD Civil 3D and save the drawing, the profile views are updated when the drawing is reopened in AutoCAD Civil 3D 2015. If you edit the projection style in a prior version of AutoCAD Civil 3D to display AutoCAD solids as markers and then reopen the drawing in AutoCAD Civil 3D 2015, the projected solids are displayed as markers and the projection style is set to display the solids as markers.
Free vertical curves that are created with the new Free Vertical Curve (Circular) and Free Vertical Curve (Parabolic) commands and which use a pass-through point as their constraint type will not be displayed if the drawing is opened in a prior version of AutoCAD Civil 3D. These curves must be converted to use a different constraint type such as length or K value if you intend to use the drawing in prior versions. To streamline the conversion, you can use the new Convert Free Curve (Through Point) command which is located in the Profile Layout Tools toolbar.
Horizontal change notification symbols are saved in the drawing but will not be displayed if the drawing is opened in a prior version of AutoCAD Civil 3D.
Opening a prior-version drawing in AutoCAD Civil 3D 2015, and then editing the properties of a subassembly that was created in Autodesk Subassembly Composer (a PKT file), will result in the subassembly not being found when you re-open the drawing in a prior version of the application (even if you do not save the drawing in AutoCAD Civil 3D 2015). This occurs because some modifications are made to the custom subassembly files when the subassembly properties are modified in AutoCAD Civil 3D 2015.
Therefore, before using AutoCAD Civil 3D 2015 to work with existing drawings that contain custom subassemblies, it is strongly recommended that you create a backup of the C:\ProgramData\Autodesk\C3D <version>\enu\Imported Tools\<PKT name> folders. These backups can be used if you want to work with the drawing in a prior version of the application.
After editing the subassembly properties in AutoCAD Civil 3D 2015, and before re-opening the drawing in the prior version of the application, use the backups to overwrite the contents of the C:\ProgramData\Autodesk\C3D <version>\enu\Imported Tools\<PKT name> folders. This process will need to be repeated each time you want to work with the drawing in a prior version of the application after editing the subassembly properties in AutoCAD Civil 3D 2015.
If you do not have backups of the C:\ProgramData\Autodesk\C3D <version>\enu\Imported Tools\<PKT name> folders that you can use when you want to work with the drawing in a prior version of the application, you can use the following process to restore the subassembly: