I also have the following signs, derail, close clearance, rural 45 degree crossbuck, etc. Photos available upon request:-)
I believe the white rectangular sign with black dots is also for wedge plows. They have a blade between the rails that is to be lifted before crossings, or they tear out the crossing planks. I recommend the following videos that show wedge plows in action and the blade being raised and lowered:
Greg Scholl Video Productions: "Plow Extras" and "Snow Plow with CN F7's" Both feature branchlines that no longer exist in Southern Ontario.
http://www.gregschollvideo.com/snowplow-dvds.html
Rail Innovations: Branchlines in Transition. It might be "Towers and Branchlines" Not sure as the link does work.
http://web.archive.org/web/200712270217 ... m/main.htm This video also features a plow extra on the now abandoned branchine from Orangeville to Owen Sound.
These are some of my favorite railfan videos and are highly recommended.