This is the HO Scale Single-Track Truss Bridge - Kit - 20 x 3-1/4 x 5'' from Walthers.
Found on railroads large and small, truss bridges are the most common type used by railroads. Installed anywhere a longer span is needed, truss bridges like this model are used above streams, rivers, other rail lines and roads where clearance is required below the structure. With its realistic trusses, chords and bridge shoes, it adds authenticity to your right of way. Safety sign and graffiti decals let you add the finishing touch. Because these structures have been in use since the late 1800s, this bridge will look right on any steam-era pike, yet its tall enough to clear modern double-stacks and auto racks.