This bridge supports railroad tracks without ballast. The wooden ties rest on steel channels supported on the floor beams, which in turn are supported by the vertical hangers.
The abutments were cleanly mortared with extruded joints and built with three steps. The lowest step is under the bottom chord and may be used for jacking up the truss. The second step supports the truss and the tracks run across the top.
The bridge appears to be in good condition. It crosses over a little stream that may be a branch of Rio Armeria. It seems like a rather light structure to carry heavy trains, but that's what makes truss bridges so effective.
Mexico's Bridges: Puente Rojo del Ferrocarril (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.