Shoring should keep pace with the excavation. When earthmoving machinery is in use, whether any length of trench can stay unsupported should be decided by risk assessment. The SWMS system of work should keep workers out of unprotected parts of the excavation and stop them working beyond the shoring while it is being installed progressively. The basic types are hydraulic metal shoring and timber shoring; metal shoring, commonly hydraulic jacks with steel struts, walls and sheeting, has largely replaced timber because it spreads pressure evenly and adapts to different depths and widths. Common types include ground anchors, prefabricated concrete panels, timber systems such as soldier sets, steel trench sheeting, steel sheet piling and hydraulic systems.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.