If you need additional linetype for a drawing you can follow the steps below
Type in LINETYPE in the commandline of your AutoCAD Civil3d
Click on the load button at the top
Then click on the file button at the left top.
Once you have got this far you now need to navigate your way to C:\ProgramData\CSS\Stringer 20??\ADITCAD folder shortcut/aditcad and find a file name Stringer.LIN which has all different line types in there for you, select it and click Open.
When you go back to the previous screen you need to select a linetype from the list and then Select Control A on the keyboard (this will highlight all linetypes in there) then click OK and all the linetypes will have been added into the drawing.