This document discusses excavation work, including different types, measurement methods, and depth classifications. It explains that excavation involves removing topsoil and soil to specific depths according to an engineer's plans. Depth is classified into categories to account for increased difficulty and safety risks. Measurement of excavation works involves determining the area and depth of cut according to clauses, including distinguishing between normal soil and rock. Temporary supports like planking and sheeting may be needed to stabilize excavations depending on soil conditions.