Short loads cost more $$$ per yard than full loads. It costs the same for the ready mix company to ship 3 cu yds as it does to haul 10 cu yds, hence the $$$/yd difference. Another thing to consider is the unloading time on the job. We allowed 5 minutes/yd to unload, after that it added 1$/minute to the bill (stand by time). There were freight zones, distance between job and plant, that influence $$$ also.