Last I'd heard the bridge and track were still "active" but only in the sense that it's the museum's link to the outside world.
Judging from the pic it looks as though the stored cars are new exhibits donated to the museum.
The red carding of the bridge may be due to the major flooding that hit the museum a few years back and damaged everything in the collection so with other locomotives and rolling stock being a higher priority(to keep money coming in)getting the museum's outside link repaired may need to wait until they have something to go in or out.
Just an observation: it appears to be a pony girder span, rather than a through truss.