This is the 50' 1930's Highway Overpass in HO Scale by Rix Products.
These vintage highway overpass kits model concrete bridges built in the 1930s and 1940s, which are still used today. All parts are molded in realistic concrete color. Each overpass section is a scale 50' long and 25' wide. Modular design and interlocking parts make it easy to build longer overpasses.