S-2.1, r. 9 - Regulation respecting concrete pumps and distribution masts
14. A guard-rail shall
(1) be comprised of an upper rail and a mid-rail placed at mid-height and solidly fixed to the inside of the posts;
(2) be made of metal;
(3) withstand a concentrated horizontal force of 900 N applied to any point of the upper rail; and
(4) withstand a concentrated vertical force of 450 N applied to any point of the upper rail.