Whether or not HOA funds are authorized to be used for the mowing of grass in the median of a state highway with respect to the planned unit development that you live in would be set forth in the recorded covenants, conditions and restrictions and/or the approved rules and regulations of the community that you reside in.As such you need to carefully read these documents. If not so stated, then the funds cannot be used for such a purpose. Personally, the use of the HOA funds for the purpose that you have written about seems to be a waste of good money to me.