I presume you are referring to tracks running longitudinally on two levels, not simply tracks on a bridge crossing over tracks at ground level.
Many years ago, some of the industrial tracks in Brooklyn ran at ground level underneath the (then) BMT elevated rapid transit tracks.
During (or shortly before) the same era, there were literally miles of streetcar tracks in the roadways under the (then) IRT elevated structures in Da Bronx. The Broadway swing bridge had two levels of track, streetcars in the roadway at ground level and rapid transit above.
(The Broadway bridge is still two level, but the only tracks are on the upper level. The lower level is used only by motor vehicles and pedestrians.)
I'm sure there were places where the through tracks were raised, and the industrial leads were tucked underneath them.
Chuck (modeling Central Japan in September, 1964)
That is exactly what I mean. I plan to have a double track mainline raised above a single track industrial lead that will run along the same path for a good two feet or so.
Thanks for the hints - I'll go see if I can hunt down some images!
Here is an example of something somewhat like that in Benicia, CA.
Example 1
There is also a location where they cross closer to a right angle.
Example 2
"No soup for you!" - Yev Kassem (from Seinfeld)
Although they're long gone now, there used to be numerous streetcar lines and industrial sidings along the Mississippi River waterfront in Saint Louis, and passenger trains entering or leaving Union Station ran on an elevated line on a long deck girder bridge to avoid the periodic floods.
If you could find rail maps from the early 1900's through 1960 or so, these lines should appear on them.