Use of NRA and CESMM3 Methods in Civil Engineering Measurement - Assignment Example

Differences between the NRA method of measurement and CESMM3 Civil Engineering Measurement E (Earthworks) In CESMM3, all measurements are in cubic meters and the activities include; I. Excavation II. Dredging III. Filling IV. Compaction V. Disposal and VI. Landscaping. Activities excluded are excavation for; I. Ground excavation II. Diaphragm walls and ground anchorages III. Pipes and sewers, manholes, trenches and ditches, pipe headings, thrust boring and pipe jacking and jointing IV. Piles V. Foundations for traffic signs VI. Foundations for fences and gates VII. Tunnels, shafts, headings and other subterranean cavities. The types of excavation available are dredging, cuttings, foundations and general. Their depths also vary depending on ground material. For; I. Top soils, the depth should not be more than 0.25m. II. Firm ground to range between 0.5-1.0m. III. Any surface initially exposing hard material, a depth of 1-2m (CESSM3, 1991 p.34). NRA works on an assumption that one cubic meter of excavated material equals one cubic meter of compacted material. The measurement is done for; I. The topsoil 5A II. Cutting and other excavation III. Surcharge removal IV. Structural foundations V. Foundations for corrugated structures that are buried. The required depth is; I. 0-3 meters and II. 0-6 meters or more in steps of three (National Roads Authority 2000 p.92). 2. Class F: In-situ concrete All measurements are in cubic meters for CESMMA3 and NRA. According to CESMM3, measurements for in-situ concrete exclude; I. Capping of boreholes II. Diaphragm walls III. Excavation ancillaries IV. Granolithic and other applied finishes V. Drainage and pipework VI. Piles VII. Roads, pavings and kerbs VIII. Tunnel and shaft linings IX. Foundations for fences and gates. The concrete has different design mix. Various thicknesses are indicated in the placing of concrete. For blinding, a thickness of not greater than 150mm is allowed. The footings, bases and the like, a thickness of 150-300mm. for suspended slabs, it varies between 300-500mm and walls not to exceed 500mm (CESSM3, 1991 p.40). According to NRA, in situ concrete is measured in cubic meters without deductions for: I. The holes, ducts, pockets, sockets, mortices and the like should not exceed a volume of 0.15 cubic meters each. II. Individual chamfers, splays, rebates, recesses, drips, grooves and the like of 1000mm or less in girth must be of concrete. III. For concrete of patterned profile, indentions of 100mm or less in girth in measurement over the indentions created in concrete IV. Reinforcement V. Components cast of a maximum 0.15 cubic meters in volume. 3. Class G: Concrete Ancillaries The measurements for CESMMA3 and NRA are in square meters. CESMMA3 measurements in this class include; I. Formwork for in situ concrete II. Reinforcement for in situ concrete III. Joints in in situ concrete IV. Post-tensioned prestressing V. Accessories for in situ concrete. It excludes: I. Reinforcement in diaphragm walls II. Pre-tensioned prestressing III. Formwork and reinforcement in precast concrete IV. Formwork and reinforcement ancillary to drainage and pipework V. Formwork and reinforcement in piles VI. Formwork and reinforcement for concrete roads and pavings VII. Formwork for tunnel and shaft linings VIII. Formwork for foundation for fences and gates. Formwork is classified according to the type of finish, that is, rough, fair, stated finish and stated surface features. The formworks also vary on plane, curves, voids, and constant cross-section concrete (CESSM3, 1991 p.42). Formwork for NRA can be patterned profile formwork measured in square meters. 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. 4. Class I: Pipework- pipes CESMMA3 measurements include; I. Provision, laying and jointing of pipes II. Excavating and backfilling pipes trenches. And excludes; III. Work included in classes J, K, L and Y. IV. Piped building services. 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). 5. Class J: Pipework- Fittings and Valves CESMMA3 measurements covers; I. Fittings and valves for pipework And excludes II. Work included in classes I,K,L and Y III. Piped building services. This is included in class Z. The types of pipes covered are; clay pipes, concrete, iron or steel, polyvinyl chloride, glass reinforced plastic and high and medium density polyethylene. Nominal bore classes are; I. Those that do not exceed 200mm II. Between 200-300mm III. Between 300-600mm IV. Between 600-900mm V. Between 900-1200mm VI. Between 1200-1500mm VII. Between 1500-1800mm VIII. And those that exceed 1800mm. It covers valves and penstocks. The valves covered are gate, non-return, butterfly, air and pressure reducing valves (CESSM3, 1991 p.50). 6. Class K: Pipework- Manholes and Pipework ancillaries CESMM3 measurements under this class include manholes and other chambers, ducts, culverts, crossings and reinstatement and other ancillaries. It excludes; I. Work included in classes I,J,L and Y II. Ducted building services. Material used for manholes could be bricks, in situ concrete and precast concrete or with backdrops for all. This also covers other stated chambers (CESSM3, 1991 p.52). 7. Class L: Pipework- Supports and Protection, Ancillaries to laying and Excavation According to CESMMA3, activities includes are; I. Extras to excavation and back filling of trenches for pipework, ducts and metal covers, manholes and other chambers, headings, thrust boring and pipe jacking II. Pipe laying in headings and by thrust boring and pipe jacking III. Provision of supports and protection to pipework, ducts and metal covers And excludes; IV. Work included in Classes I,J,K and Y V. Insulation to building services (CESSM3, 1991 p.56). 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; I. Internal faces of chambers II. External faces of headwalls III. Intersections of center lines at pipe junctions IV. Center of gully gratings V. Termination position in the contract and VI. Point of change of stage depth. The depth of the drains is vertical measurement between the invert and; I. When it is below the existing ground level II. It is at or above existing ground level. 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. 8. Class A: 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 inserted under general directions in the Bill of Quantities. It highlights accommodation for the contractor and the engineer. For contractors accommodation, everything required by the contractor are included. For the engineer, what is included are; rent and lease, heating, sanitation, power, lighting and water, disposal waste and the like. Dismantling of temporary accommodation is also included. Activities realized are; receiving items back from the engineer, disconnections, disposal of materials, reinstatement of sites and the like. All units of measurement in this section are items (National Roads Authority 2000 p.33). Vehicle for the engineer is measured in vehicle week and inclusive of equipment, taxes, comprehensive insurance, depreciation and the like. Communication for the engineer is measured as an item and provided until completion of works (National Roads Authority 2000 p.36). 9. Class W: Waterproofing Areas covered in CESSM3 are damp proofing, tanking and roofing excluding water proofed joints, damp proof courses of bricks, blocks and masonry and surface finishes and linings for simple structures. For the inclusions, further division is made for asphalt, sheet metal, water proofing sheeting and coating and rendering both for ordinary and water proof cement mortar and tiles (CESSM3 1991 p.92). NRA puts emphasis on waterproofing Anchorage Boreholes. Unit of measurement is linear meters. The items are in accordance to general directions in the Bill of Quantities and include pre-grouting, re-drilling and for water under high pressure as well as providing water tightness of the borehole (National Roads Authority 2000 p.120). Reference List Institution of Civil Engineers, CESMM3, Civil Engineering Standard Method of Measurement, 3rd Ed. 1991, Thomas Telford. London. National Roads Authority, 2000. Method of Measurements for Road Works. Manual of Contract Documents for Road Works. Vol. 3, Section 1. Read More