Before we Start Autodesk Infra Works
1, we transfer the files to Infra Works, we need the following files in 3D model / 3D points / Coordinated Imagery files.
Open AuotDesk Civil 3D
2, Select the Track Alignment Centre Lines (Must be in 3D Poly Line)
3, in Civil 3D we will generate 3D points line for Railway Alignment and Use the command Mapexport to save the file in SDF Format.

Open AuotDesk Navis Works
4, from Navisworks Export the Embankment Elements to FBX Format.

Go to Google Earth
Import Google Earth Image in to Autocad and Save as Raster Image
Save all the above files in to selected folder. If you any other files like Bridges, Roads all export to SDF or FBX format.
Goto Infra Works
A, Select the Google Earth Raster Image and Configure
B, Select the Track centre Line SDF File and Configure
3, Select the Bridge 3D Object file and Configure