the employer shall ensure at a construction site of building or other construction work that -
(a) runway or ramps provided for use by building workers is not less than four hundred and thirty millimeters in width and is constructed of not less than twenty-five millimeter thick planking or any other material of adequate strength to withstand the required load supported substantially in relation to the span and braced of such runway or ramp and design and construction of such runway or ramp is in accordance with the relevant national standards;
(b) every runway or ramp provided for use of building workers located more than three metres above the floor or ground is on open sides provided with a guard rail of adequate strength and height of not less than one thousand millimeters.