Impartial tests show that the MB-12 meter box stands up easier under heavier loads than they would normally be subjected. Compressive Tests: Boxes withstood traffic of 45,000 pounds. Tested on a universal Tinius-Olsen testing machine by Law Engineering and Testing Company, Geotechnical and materials Engineers, PO Box 13215, 1412 Plasters Ave., NE, Atlanta, Georgia 30324.