Single-post, temporary sign support with sandbag ballast

Oregon DOT has a single-post temporary sign support (TSS) for the installation of signs less than 9 sq. ft. The state allows the placement of ballast in the form of sandbags on the legs of the TSS. Each bag shall be limited to 25 pounds, but there is no limit on the number of bags placed on the legs.
The web site below provides the state’s Standard Drawings (drawing TM821)
The design for the TSS comes from the 2002 AASHTO Roadside Design Guide, Chapter 9, Figure 9.36.