As you have already noticed, beside so many cool features, Civil 3D can also publish objects to Google Earth so we can now visualize how our corridor, alignment, parcel, etc. look on the ground. All you need to do is to install Google Earth Extension for AutoCAD Civil 3D. AutoCAD Civil 3D 2009 version comes with extensions while for previous versions could be downloaded from this site: http://labs.autodesk.com/utilities/google_earth_extension_beta/
But, that is an old news. What I am about to do here is to provide a workaround for displaying lines to be legible on the Google Earth image. For some reason all lines published to Google Earth’s KML file are shown with 4.0 widths. Back in Civil 3D 2009 you made sure all lines are 0.0 width. To illustrate…. you wanted your image to look like the one called “After” but you got is “Before”.
That setting is part of the Style Setting of Google Earth. If you publish your object in Google Earth on the left side of the screen you should see the file name you just published (Places). Right-click on it and choose Properties. Then you will see Style, Color tab where yo u should be able to set Width from 4.0 to whatever you wish. But this will only take care of the line you selected or multiple objects you selected.
There is another workaround to achieve your ultimate goal of having “Before” image look like “After” image. Again, it seems that Google Earth default is still 0.0 only if the lines are coming in default line weight. So by changing all layers from 0.00 (or other widths) to default in Layer manager within AutoCAD Civil 3D and then using File>Publish to Google Earth or PUBLISHKML command to publish this can be achieved. By the way, make sure you don’t use “Elevation relative to sea level” in the Publish AutoCAD DWG to Google Earth dialog if you want to be able to see your objects….like I didn’t.