It is not measured to construction joints, holes, ducts, sockets, mortices and the like that do not exceed 0.15 cubic meters in volume. The edge of blinding concrete should be less or equal to 75mm. An inclination angle of less than 15° to horizontal plane is required.
The pipes are measured in linear meters and made of clay, concrete, iron, steel, polyvinyl and glass reinforced plastic. The depth of excavation depends on the nominal pipe diameter and type of material for the pipe (CESSM3, 1991 p.48).
NRA dwells puts a lot of emphasis on drainage and service ducts include drains, sewers, piped culverts and service ducts. It does not include filter drains, narrow filter drains and fin drains. The unit of measurement is linear meters. The measurement done from the center line between;
For depth inverts that do not exceed 2m, average depth of invert to be stated the nearest 25mm. If the depths to invert exceed 2m but less than 4m and in steps of 2m, again the average depth must be stated to the nearest 25mm.
From the CESSM3 point of view, unit of measurement for executed works is in sum form apart from scenarios where there is a specified unit of measurement. The divisions included are; contractual, specified requirements, method related charges, provisional sum and the rest. Contractual requirements are classified into performance bond, insurance of works and third party insurance. Specified requirements refer to accommodation, services, equipment, attendance for engineers’ staff and the like. The method-related charges focus on accommodation, services, temporary works, supervision and labour and plant. Provisional sums are measured in terms of day work and include; labour, materials, plant and their respective percentage adjustment. Method-related charges are inserted by the tenderer in the Bill of Quantities (CESSM3, 1991 p.16).
NRA classifies this section under preliminaries and