Automated systems and methods of manufacturing truss elements for use in modular construction units can include stations, or steps, for forming angled webs, upright webs, and truss chords for use in the truss elements, transferring such angled webs, upright webs, and truss chords onto an assembly jig in a configuration corresponding to the truss element being manufactured, rigidly interconnecting, via nail plates, the angled webs, the upright webs, and the truss chords to form a finished truss element, and unloading the finished truss element from the assembly jig.