Lecture 1 Quantity Surveying and Specification PDF

‫حساب الكميات والمواصفات‬ Quantity Surveying and specification Lecture 1 1 Abdelrahman Aqel Abueladas Surveying & Geomatics Engineering Department ...

‫حساب الكميات والمواصفات‬ Quantity Surveying and specification Lecture 1 1 Abdelrahman Aqel Abueladas Surveying & Geomatics Engineering Department  Quantity Surveying and specification What is Engineering Project Definition of Quantity Survey ًً‫انًسح انك‬ Importance of Quantity Survey Required Data for the Preparation of an Estimate or Quantity Survey Types of Estimates and Quantity Survey 2 Dr. Abdelrahman Abueladas  Introduction Engineering Projects: All start with map of the site where the future structure or utility will be. The LAND value has to be estimated as a part of the project, especially when expropriated , and when this requires computation of area. The CONTRACT is signed between the owner of the project and the design company. Specialists design the structure (utility), producing large variety of design; the design process costs money. Another contract is signed between owner of the project and building company. The design drawings are transferred to the field by surveyors and marked so building contractor knows where and what must be built. The constructor executes the construction works over some period of time and receives payment according the signed contract. Dr. Abdelrahman Abueladas 3  Introduction Dr. Abdelrahman Abueladas 4 Earth works: Cut and Fill Excavations and embankment. Borrow pits and waste. Earth works are involved in: All engineering projects. Mining. Land development. Precise computation of volume is very important because: a) High cost of earthworks. b) Errors in estimation lead to conflicts, litigation, and often failure of the project.\ Dr. Abdelrahman Abueladas 5 Earth works: are computed and volumes of cut and fill (excavation and embankment) using: a) Direct survey measurement in the field before and after excavation and /or embankment, e.g. mining. b) Photogrammetry: comparing digital elevation models from overlapping aerial photographs before and after the project. c) Profiles and cross sections. d) Contour maps and engineering drawings. Dr. Abdelrahman Abueladas 6 Dr. Abdelrahman Abueladas 7 Definition of Quantity Survey : Quantity survey is defined as a schedule of quantities of all the items of work in a building. Quantity surveying is a term or process used in the construction industry to take measurements of civil works, prepare specifications, and estimate the cost of works either for each trade/item of work or for the whole project. The term “surveying” means to inspect, study, review, investigate, asses, and hence “to measure”. Therefore the term “quantity surveying” means “quantity measuring” as applied to civil engineering projects. 8 Dr. Abdelrahman Abueladas  Estimating Estimating: is the technique of calculating the various quantities and the expected Expenditure to be incurred on a particular work or a project. Estimation: is the scientific way of working out the approximate cost of an engineering project before execution of the work. It is totally different from calculation of the exact cost after completion of the project. 9 Dr. Abdelrahman Abueladas To prepare an estimate, you have to answer two basic questions: 1–How much work is to be done? 2–What will it cost to do this work? The process of measuring work is called taking off. Quantity take-offs (QTO) are a detailed measurement of materials and labor needed to complete a construction project. They are developed by an estimator during the preconstruction phase. These measurements are used to format a bid on the scope of construction. The taking off is processed and priced in a number of different ways, depending upon : a) The type of construction. b) The contract involved. 10 Dr. Abdelrahman Abueladas  Estimation requires a thorough knowledge of: 1- The construction procedures. 2- Cost of materials & labor. 3- The skill, experience. 4- Sound engineering judgment. An estimate of the cost of a construction job is the probable cost of that job as computed from plans and specifications 11 Dr. Abdelrahman Abueladas  Notes Quantity surveyors plays crucial role during the project implementation either with the consultant or with the contractor For a good estimate , the actual cost of the proposed work after completion should not differ by more than 5 to 10% from its approximate cost estimate, providing there are no unusual, unforeseen circumstances. 12 Dr. Abdelrahman Abueladas What are the tasks covered in quantity surveying? 1. Preparation of Specifications. 2. Taking measurements of civil works. 3. Preparation of approximate (preliminary) cost estimate at the very early stage of the project. 4. Preparation of detail cost estimate at different stages (taking as built measurements and preparing payment certificates or approval of payment certificates prepared by taking measurements) 5. Valuation of property 13 Dr. Abdelrahman Abueladas What are the major factors influencing on estimate accuracy? 1-Quality and amount of project information (design, costs, etc..) available for preparing the estimate; 2-Time allocated to prepare the estimate; 3- Proficiency/experience of the estimator and the estimating team; 4- Methods, tools and techniques used in preparing the estimate. 14 Dr. Abdelrahman Abueladas What are the essential qualities of a good estimator? To prepare a good estimate, the estimator must 1- Have good knowledge regarding the important rules of quantity surveying and select a good method for estimation 2- Must thoroughly understand the drawings of the structure and have experience in dealing with details of construction work 3- Have ability to collect, classify and evaluate data relating to estimation 4- Must also be clearly informed about the specifications (showing nature and classes of works, materials and machinery), because the rates - at which various types of works can be executed- depend upon its specification 15 Dr. Abdelrahman Abueladas What are the essential qualities of a good estimator? To prepare a good estimate, the estimator must 5-Have ability to visualize all the steps during the process of construction 6-Before preparing the estimate, the estimator should visit the site and make a study of conditions, there. 16 Dr. Abdelrahman Abueladas  ‫‪‬مراحم حساب انكميات‬ ‫أ) إعذاد انقٍاساخ و انحساتاخ انهُذسٍح نألعًال عهى يزحهتٍٍ ‪:‬‬ ‫انمرحهة األونى ‪ :‬يٍ انًخططاخ انتصًًٍٍح‬ ‫انمرحهة انثانية ‪ :‬يٍ يىقع انعًم‬ ‫ب) إعذاد جذاول انكًٍاخ ووضع انتكهفح انتقذٌزٌح‬ ‫ج) إعذاد و يزاجعح انًستخهصاخ انًانٍح‬ ‫‪‬انمراحم انرئيسية في انمشاريع انهنذسية‬ ‫ يزحهح اإلعذاد‬ ‫ يزحهح تزسٍح انعطاء و انتُفٍذ و اإلشزاف‬ ‫ يزحهح استالو و تشغٍم انًشزوع وصٍاَته‬ ‫‪17‬‬ ‫‪Dr. Abdelrahman Abueladas‬‬  ‫‪‬وثائق انعطاء‬ ‫ انًخططاخ انتصًًٍٍح‬ ‫ جذاول انكًٍاخ‬ ‫ انًىاصفاخ انفٍُح‬ ‫ انشزوط انعايح و انخاصح‬ ‫ انًستُذاخ و انًالحق انقاَىٍَح‬ ‫‪‬أطراف انمشروع انهنذسي‬ ‫ انًانك أو انًًىل و هى صاحة انعًم‬ ‫ االستشاري (انًكتة انهُذسً انًصًى و انًشزف)‬ ‫ انًقاول‬ ‫‪18‬‬ ‫‪Dr. Abdelrahman Abueladas‬‬  ‫‪‬أعمال إنشاء انمثاني‬ ‫ أعًال انحفز وانزدو ‪Landfill work‬‬ ‫ أعًال انخزساَح‬ ‫ أعًال انثُاء‬ ‫ أعًال انقصارج‬ ‫ أعًال انثالط وانزخاو‬ ‫ أعًال انذهاٌ‬ ‫ أعًال انخشة و األتىاب‬ ‫ أعًال انشثاتٍك واألنًٍُىو‬ ‫ أعًال انكهزتاء‬ ‫ األعًال انصحٍح و انًٍكاٍَكٍح‬ ‫‪19‬‬ ‫‪Dr. Abdelrahman Abueladas‬‬  ‫وحذات انقياس انهنذسية انمستخذمة في حساب انكميات‬ Units of Measurements (lump-sum) : ‫ انمقطىعية‬ A single payment made at a particular time, as opposed to a number of smaller payments or installments. (R.M) :‫ انمتر انطىني‬ Works consists linear measurements involve length like fencing, hand rail, etc., are expressed in running meters (RM) ) No. (: ‫ انعذد‬ Single units work like doors, windows, trusses‫ و‬etc., is expressed in numbers. 20 Dr. Abdelrahman Abueladas  ‫وحذات انقياس انهنذسية انمستخذمة في حساب انكميات‬ Units of Measurements Area = Length ×Width : (m2) ‫ انمتر انمرتع‬ Works consist a real surface measurements involve area like plastering, white washing, partitions of specified thickness etc., and are expressed in square meters (m2). (m3) ‫ انمتر انمكعة‬ Volume = Length ×Width ×(Height or Thickness) = Area of cross-section ×Length Works consist cubic contents which involve volume like earth work, cement concrete, Masonry etc.. are expressed in Cubic meters (m3). 21 Dr. Abdelrahman Abueladas  ‫وحذات انقياس انهنذسية انمستخذمة في حساب انكميات‬ Units of Measurements. (Kg-ton) ‫ انىزن‬ Works consist weight contents which involve weights like reinforcing steel, cement, etc.. are expressed in kg. (Day-Hour ) ‫ انيىمية أو انساعة‬ 22 Dr. Abdelrahman Abueladas  Degrees of accuracy in Measurement Areas measure to the nearest 0.01 squared meter Steel work areas measure to the nearest 0.001 m2 Volume measure to the nearest 0.01 m3 Wood work volume measure to the nearest 0.001 m3 Weights measure to the nearest 1 kg 23 Dr. Abdelrahman Abueladas