When I got Train Simulator 2014, I got bored of it very quickly. So I searched for addons, and I literally spent a few days trying to search the internet for good addons for RailWorks 4. 
So to save other people from hopelessly searching like I did, here's all the ones that I found and thought are worth downloading.
Also I have converted all the *.7z files into (legacy) *.zip files, so they can be opened without using 7-zip.

Tested on this RailWorks 4 torrent:  /torrent/8417659/

To install any of these, simply extract and move to your RailWorks root folder.
These files have been all been scanned using Eset smart security 5.

As always, please seed! and happy driving :-)