This is the HO Scale Pennsylvania Railroad Standard Coal Trestle - LASERkit(R) Kit from American Model Builders.
The Pennsylvania issued drawing #59146 in 1907 (and revised it in 1911) for a standard coal unloading trestle. The usual length of the light-duty design was 75', but could be extended if needed. Bents were used to form storage bins below the tracks so hoppers could be quickly unloaded by gravity.
This kit features 100% laser-cut components to speed assembly and eliminate the need for jigs -- all the hard work has been done by the laser! Timbers are pre-notched to simplify assembly of bents, stringers and bracing. Laser-scribed boards are provided for the bins beneath the trestle and walkways, which also include delicate handrails. Micro-Engineering Code 70 rail is provided, along with a combination gauge to keep rail and ties properly spaced.