As I write this, CN work crews are commissioning the new controlled location at Waterdown West, which connects the west end of track 4 back to the mainline. This will allow half-hourly service to Hamilton using only a single track between Bayview and Burlington West, keeping GO trains separate from CN's busy mainline.
I posted some preliminary photos in
this Twitter thread, and will post some higher-quality ones once I dump my SD cards off my good camera. Since I'm out here already, I may as well stick around for another few hours till sunrise to get some photos by daylight.