Other factors include Vibration and loads from traffic. Position of water table. Time which the excavation remains open. They are placed vertically and support the soil at the sides. Walings Cross-section ftom 175 x 50 mm to 225 x 75 mm.
Longitudinal members running the length of the trench, they support poling boards.
Struts Usually square timbers, either 100 x 100 mm or 150 x 150 mm in size. Spaced approximately at 1.8 m centres to allow for adequate working between. Used to support the walings. Sheeting Common size is 175 x 50 mm. Consists of horizontal boards abutting one another to provide a continuous barrier, for excavation in loose soils.