Bruce,

This line may well be one of the Train Simulator routes.
It is certainly scenic enough. It was not the the primary
Orient Express route, which went between Paris and
Salzburg (and then Vienna, etc.), by a different route.
Howver, the "nostalgia" Orient Express probably did run
on this more scenic route.

No, there is not a tunnel immediately to the right of the
bridge, the next tunnel is somewhat around a curve, perhaps
half a mile away.

I have been on this line on cab rides several times. While
this is a great line to view from the engine, the Trisana
Bridge itself is rather mundane from that angle.

I do have photos from the other side of the bridge, which
shows the line curving at the end of the bridge, but I
don't have any of these scanned at the moment.

-- Ernest