Thanks Keith K
So it looks like it is a 2 track bridge with a center rail to center rail width of 4" ( so probably 6" wide opening).
It also suggests an elevation of 5 3/4 " from base of bridge to bottom of track.
So you need to trestle.
Height to track bottom of 6 1/2 " is the killer.
(Overall height of opening between bottom of track and bridge superstructure).
Oh well...question answered.
Thanks.