I'd be pleasantly surprised if they went ahead with the widening right away. Service patterns aren't going to require 2 tracks for some time, so I'd expect the single-trackage on a twin-track bridge to be the reality for a few years now. At least until double tracking progress along the rest of the line requires it...
Again though, I'd love to be surprised!
The various powerpoints from community consultations seemed to imply that the widened ramp is within the existing contract and work plan. I would be surprised if they don't get that grading done once the first track is in service and the existing track is removed. I agree that there wont be need for the second track for a while, but if nothing else, finishing the grading stands in the way of getting on with the linear park, so I would expect it should be done quickly. And, that way we have the original contractor finishing the work without demobilising and then having to remobilise later.
As far as completing on time, it does look like it may be a tight race. The orange tarping in those latest photos implies that concrete is still being poured. I wonder how long that will take to complete that work down the entire length of the guideway. And, I wonder whether the contractor is eager to do other finishing up tasks once trains are running on the guideway.... that will slow down the work for things like completing the sound wall installation, and whatever tie-ins etc are needed between the two guideway lanes.
As far as actually laying the track, it's not uncommon for derailments to require the replacement of similar lengths of track. The railroads manage that in hours or days rather than weeks. So once there is completed rail on the guideway itself, laying down the ends can be done in a flash, thermite welds and all.
I wonder if the contractor has blown by their performance incentives already. If not, I would predict that we will see day-and-night work to get to the finish line on time. It's not the last minute..... yet.