Two beams, usually referred to as B-1 and B-2, run in an east-west direction and support the roof beams and panels. A third, more massive member, the "Mammoth Beam", spans the largest distance across the roof from east to west and assists in supporting the roof beams and panels. The roof of the shelter consists of 1 metre (3 ft 3 in) diameter steel pipes laid horizontally north to south, and steel panels that rest at an angle, also in the north-south direction.