bolt or pin hole 22 extends between and is open at the side faces 12 multiple lateral horizontal holes 24 also extend between and are open at the side faces 12 each lateral hole 24 is located between a respective crossarm end 10 and the medial bolt hole 22 vertical holes 29 can be provided at suitable locations in the crossarm 6 for example at spaced locations for mounting electrical insulators 25 a b hangers etc the crossarm 6 includes radiussed upper and lower edges 21 a b each brace 8 includes inner and outer ends 26 28 the brace inner ends 26 are 9 mounted on the utility pole 4 by a brace pole mounting bolt 29 the brace outer ends 28 are mounted on the crossarm 6 by brace crossarm mounting bolts 30 extending through brace outer ends 28 and respective lateral bolt holes 24 fig6 is a schematic diagram showing a system for practicing a method of manufacturing structural members such as the crossarm 6 and the crossarm assembly 2 the method includes the steps of providing a source 32 of plastic pellets without limitation of the generality of useful plastic base materials for the crossarm 2 polypropylene homopolymer base material e g nt 418 t001 8000 with 20 to 30 chopped glass fibers has been found to be particularly suitable for use in the manufacture of the crossarm 6 additives for the manufacturing process include pigment 34 a uv inhibitors 34 b and antioxidant additives 34 c a foaming agent source 34 d is also provided and introduces a suitable endothermic foaming or blowing agent such.