1、TextEstimating is determining how to construct the specified work in the most economical manner and wihin the time allowed by the conract1.The format of all esimates should be as possible.A work breakdown structure should be esablished for this purpose.An alternate mathod to detaied task-by-task est
2、imate preparation,especially in the early stages of project development when details are not available,is parametric esimating.Direct costs are those costs that can be aributed to a single task of construction work.Indirect costs are those costs that cannot be attributed to a single task of construc
3、tion work2.1.IntroducionOne of the most consequential elements that govern the success of a construction company is the ability to prepare fully detailed and accurate estimates for the cost of performing work.In many companies the estimator is one of the most highly paid positions.For a typical faci
4、lity,cost estimates can be divided into a series of different types throughout the projects development and life(Fig.24-1).The types of estimates are:TextFig24-1Esimate accuracy versus percenage of engineering completeText1.1Estimating for conceptual planning.An esimate at this stage in a projects d
5、evelopment is,by necessiy,based on only very general parameters of facility size,anticipated quality of construction,and use of the facility3.Such a conceptual estimate should be prepared with considerable input from the projec owner.The owner should approve the scope document that serves as the est
6、imate as the scope identifies the baseline from which the estimae is derived.The accuracy expected is in the order of plus or minus 15 to 25%.These esimates are prepared for early budgets to determine project feasibility and to develop project financing.1.2Estimaes for feasibility.Using preliminary
7、design information and after project scope is completely defined,a broad budget feasibily estimae can be prepared.Major items of equipment can be priced and their costs input into the esimate.The local labor market should be checked for qualified craftsmen.With the better scope definition,the accura
8、cy expected is in the order of plus or minus 10 to15%.1.3Esimates during engineering and design.Based on schematic level design documents,major quantities can be quantified(ton of steel)and types of construction(steel vs.concrete)identified.An estimate with an accuracy of plus or minus 5 to 10%can b
9、e prepared at this point in project design.Text1.4Estimates for construction.These are iemized cost computaions based on a complete set of contract documents.Construction estimates can be prepared using historical average costs or by creating crews and considering their production.The method employe
10、d depends on the type of work.Building work contractors seem to make greater use of historical daa whereas heavy/highway contractors typically estimate using crew production.In either case the expected accuracy is plus or minus 5%.1.5Esimates for change orders.These are generally performed on the pr
11、oject site in response to an owner-directed change in project scope.To provide a consistent set of elements that are applicable to bidding,budgeting,and for change order preparation,uniform methods must be employed in the asssembly of the estimate.Therefore,this chapter describes methods,procedures,
12、and formats for the preparation of construcion cost estimates.All expected costs should be included in the cost estimate.An engineers estimate should be developed as accurately as possible,in as much detail as can be assumed,and should be based on the best information available4.Text2.Estimating Met
13、hodologyWhenever adequate design information is known,detailed estimating methods are to be employed.When details cannot be reasonably assumed,historical unit prices can be used.The methodologies and procedures described here are applicable whether the cost estimate is prepared manually or by using
14、computer estimating software systems.These are detabase-driven estimaing software systems for all Construction Specifications Institute（CSI）Master Format divisions that are universally acdcepted and supported on a national level.When analyzing construction tasks in an estimate,the estimator should i
15、dentify those tasks that account for the major portion of the project costs.These tasks can be identified by applying the 80/20 rule,which states that approximaely 80%of the project cost is contained in 20%of the tasks5.Because these significant tasks account for most of the project cost,they should
16、 receive prime emphasis and effort in both esimate preparaion and review.formatn.（出版物的）版式；自（数据安排的）形式；电视节目的总安排（或计划）vt.使格式化；安排的格局；设计的版面vi.设计一个版式parametricadj.参（变）数的，参（变）量的conceptualadj.观念的，概念的anticipatevt.预感；预见；预料；先于行动；vi.过早地提出；过早地考虑（或说、做）一件事；（在口头或用文字）预言；预测feasibilityn.可行性；可能性；现实性facilityn.设备；容易；能力；灵巧
17、schematicadj.纲要的；示意的；严谨的；有章法的；n.图表，（尤指）电路原理图craftsmann.工匠（名词复数：craftsman）；手艺人；技术；技艺methodologyn.（从事某一活动的）一套方法；方法学；方法论manuallyadv.用手地，手工地universallyadv.普遍地；一般地；人人；处处New Words and PhrasesNotes（1）Estimating is determining how to construct the specified work in the most economical manner and wihin the t
18、ime allowed by the conract.预算是确定怎样以一个最经济的方式完成一个指定的工程并且在合同所容许的时间内完成。（2）Direct costs are those costs that can be aributed to a single task of construction work.Indirect costs are those costs that cannot be attributed to a single task of construction work.直接成本是那些可以归结到建筑工作的某一单项任务上的花费。间接成本是那些不能归结到建筑工作的某一
19、单项任务上的花费。（3）Estimating for conceptual planning.An esimate at this stage in a projects development is,by necessiy,based on only very general parameters of facility size,anticipated quality of construction,and use of the facility.在一个工程进展中处于这一阶段的预算（毫无疑问是必需的）仅有基于非常一般的参数来进行的，如设施尺寸、预计的建筑质量以及设施的用途。Notes（4）
20、An engineers estimate should be developed as accurately as possible,in as much detail as can be assumed,and should be based on the best information available.应进行一项由工程师完成的精度尽可能高的预算，此项预算中应采用尽可能多的详细资料并根据现有最理想的数据完成。（5）When analyzing construction tasks in an estimate,the estimator should identify those t
21、asks that account for the major portion of the project costs.These tasks can be identified by applying the 80/20 rule,which states that approximaely 80%of the project cost is contained in 20%of the tasks.在预算工作中分析施工任务时，预算师应鉴别出那些在项目成本中占优主要份额的任务。这些任务可以通过采用80/20方法得到鉴别，此方法认为项目成本中大约80%的金额包含在其中20%的项目中。1.预算
22、师必须彻底了解工作的范围以及项目环境。为了做到这点，预算师必须复查设计图表、设计说明和其他相关的内容。详细的复查可以帮助预算师了解工程顺序和周期。预算师非常有必要到工程现场进行考察，这可以使他将实际场地的情况与设计参数和细节结合起来。2.工程量核算是成本预算的重要组成部分，必须尽量精确，而且应该建立在所以可用的工程和设计资料的基础上。3.工程量应统一使用标准计量单位，并与设计使用相同的单位制（英制或公制）。为各项任务给出的工程量的详细程度取决于设计的详细程度。4.基于详细设计的预算编制时需要将人力、材料、建筑设备、后勤以及转包等直接成本分别考虑。可采用的间接成本也应加入到项目总成本中。其他影响
23、定价的因素，如成本的增加、建设的不可预见费以及收益等，也要加入到建设成本中以确定项目总成本。5.生产率是指为完成工作所需做功与时间的关系。它可以是每小时立方米、每班吨（同时给出每班时间长度）或者每小时掘进尺。Exercises（Translate the following Chinese into English,or English into Chinese）6.This is particularly importanton projects with difficult site conditions,major maintenance and repair projects,alte
24、raion/addition projects,and environmental projects.The construction sequence must be developed as as soon as possible and should be used to provide a checklist of construction requirements throughout the cost estimaing process.7.According to the American Association fo Cost Engineers,cost engineerin
25、g is defined as that area of engineering practice where engineering judgment and experience are utilized in the application of scientific principles and techniques to the problem of cost estimaion,cost control and profitablility.8.The required levels of accuracy of construcion cost estimates vary at
26、 different stages of project development,ranging from ball park figures in the early stage to fairly reliable figures for budget control before construction.9.Developing the money plan involves the functions of cost estimating,budgeting,cash flow,cost control,and construction project profitability.10.The engineers estimae is based on the completed plans and specifications when they are ready for the owner to solicit bids from construction contractor.Exercises（Translate the following Chinese into English,or English into Chinese）
