There has been some engineering work over in the siding, which formerly lead you in to the Locomotive works.It is now adjacent to the Roundhouse College.
I could see a couple of trailers stacked together, but no 99709.... identification numbers.
All I saw was written in black marker pen on the edges 'Siemens 12505' & 'Siemens 12506'
Is it possible to attain the identities of these two vehicles from this?
Sorry for the late reply, I don't think it'll be possible to identify these without getting up-close and examining them. Did you manage to get a clear photo of them?
Suspect these might be similar to the trailers visible at North Pole depot - i.e. used for moving components around the depot site internally rather than the trailers listed on here that are used as part of general track maintenance.
...alternatively could they be new translator wagons?