1、Unit16Types of Cost EstimatesTextConstruction cost estimates may be viewed from different perspectives because of different institutional requirements.In spite of many types of cost estimates used at different stages of a project，cost estimates can be best classified into three major categories acco
2、rding to their functions.A construction cost estimate serves one of the three basic functions：design，bid and control.For establishing the financing of a project，either a design estimate or a bid estimate is used.Design estimatesIn the planning and design stages of a project，various design estimates
3、reflect the progress of the design.At the very early stage，inventments eastimate is usually made before the facility is designed，and therefore must rely on the cost data of similar facilities built in the past.A preliminary estimate or conceptual estimate is based on the conceptual design of the fac
4、ility at the state when the basic technologies for the design are known.The detailed estimate or definitive estimate is made when the scope of work is clearly defined and the detailed design in progress，so that the essential features of the facility are identifiable.The engineers estimate is based o
5、n the completed plans and specifications when they are ready for the owner to solicit bids from construction contractors.In preparing these estimates，the design professional will include expected amounts for contractorsoverheads and profits.TextThe costs associated with a facility may be decomposed
6、into a hierarchy of levels that are appropriate for the purpose of cost estimation.The level of detail indecomposing the facility into tasks depends on the type of cost estimate to be prepared.For conceptual estimates，for example，the level of detail in defining tasks is quite coarse；for detailed est
7、imates，the level of detail can be quite fine.For new example，consider the cost estimates for a proposed bridge across a river.A screening estimate is made for each of the potential alternatives，such as a tied arch bridge or a cantilever truss bridge.As the bridge type is selected，suppose that e.g.th
8、e technology is chosen to be a tied arch bridge instead of some new bridge form，a preliminary estimate is made on the basis of the layout of the selected bridge form on the basis of the preliminary or conceptual design.When the detailed design has progressed to a point when the essential details are
9、 known，a detailed estimate is made on the basis of the well defined scope of the project.When the detailed plans and specifications are completed，an engineers estimate can be made on the basis of items and quantities of work.TextBid estimatesThe contractors bid estimates often reflect the desire of
10、the contractor to secure the job as well as the estimating tools at its disposal.Some contractors have well established cost estimating procedures while others do not.Since only the lowest bidder will be the winner of the contract in most bidding contests，any effort devoted to cost estimating is a l
11、oss to the contractor who is not a successful bidder.Consequently，the contractor may put in the least amount of possible effort for making a cost estimate if it believes that its chance of success is not high.If a general contractor intends to use subcontractors in the construction of a facility，it
12、may solicit price quotations for various tasks to be subcontracted to specialty subcontractors.Thus，the general subcontractor will shift the burden of cost estimating to subcontractors.If all or part of the construction is to be undertaken by the general contractor，a bid estimate may be prepared on
13、the basis of the quantity takeoffs from the plans provided by the owner or on the basis of the construction procedures devised by the contractor for implementing the project.TextFor example，the cost of a footing of a certain type and size may be found in commercial publications on cost data which ca
14、n be used to facilitate cost estimates from quantity takeoffs.However，the contractor may want to assess the actual cost of construction by considering the actual construction procedures to be used and the associated costs if the project is deemed to be different from typical designs.Hence，items such
15、 as labor，material and equipment needed to perform various tasks may be used as parameters for the cost estimates.Control estimatesBoth the owner and the contractor must adopt some base line for cost control during the construction.For the owner，a budget estimate must be adopted early enough for pla
16、nning long term financing of the facility.Consequently，the detailed estimate is often used as the budget estimate since it is sufficient definitive to reflect the project scope and is available long before the engineers estimate.As the work progresses，the budgeted cost must be revised periodically t
17、o reflect the estimated cost to completion.A revised estimated cost is necessary either because of change orders initiated by the owner or due to unexpected cost overruns or savings.TextFor the contractor，the bid estimate is usually regarded as the budget estimate，which will be Used for control purp
18、oses as well as for planning construction financing.The budgeted cost should also be updated periodically to reflect the estimated cost to completion as well as to insure adequate liquidity for the completion of the project.quotation n.报价单，估价单take of n.估计量budget estimate 概算budgeted cost 预算成本conceptu
19、al adj.概念的identifiable adj.可以确定的solicit vt.恳求hierarchy n.层次，层级tied arch bridge 系杆拱桥cantilever truss bridge 悬臂桁架桥subcontractor n.转包商，次承包商base line 底线budget control 预算控制，预算管理revise vt.修订，校订，修正，修改initiate vi.开始，发动，创始overrun n.超支building project 建筑工程bill of quantifies 数量明细表，工程量清单allocations of cost 工程费用
20、分摊estimated cost 预算价值（费用），估算成本cash flow（公司、政府等的）现金流转break down 毁掉，停顿，倒塌，中止，分解be appropriate for 对适合at ones disposal 随某人自由处理，由某人随意支配New Words and PhrasesNotes（1）As the bridge type is selected，suppose that e.g.the technology is chosen to be a tied archBridge instead of some new bridge form，a prelimina
21、ry estimate is made on the basis of the layout of the selected bridge form on the basis of the preliminary or conceptual design.一旦桥梁类型确定后，假定选定了系杆拱桥而不是其他新型桥梁，应以所选定桥型的设计图纸的初步设计或概念设计来进行设计概算。（2）If all or part of the construction is to be undertaken by the general contractor，a bid estimate may be prepare
22、d on the basis of the quantity takeoffs from the plans provided by the owner or on the basis of the construction procedures devised by the contractor for implementing the project.如果总承包商承担全部或部分建造工作，投标报价将根据业主所提供的图纸或根据执行合同的承包商设计的施工程序来确定。（3）However，the contractor may want to assess the actual cost of co
23、nstruction by considering the actual construction procedures to be used and the associated costs if the project is deemed to be different from typical designs.但是，如果认为项目不同于典型的设计，承包商的实际建筑成本应结合实际的施工程序及其相关的费用来评定。Notes（4）Consequently，the detailed estimate is often used as the budget estimate since it is
24、sufficient definitive to reflect the project scope and is available long before the engineers estimate.由于施工图预算足以明确反映施工范围，并且早在施工预算之前就可以采用，因而，施工图预算经常用做概算。（5）For the contractor，the bid estimate is usually regarded as the budget estimate，which will be Used for control purposes as well as for planning co
25、nstruction financing.对于承包商，投标报价通常被视为预算费用，它将用做费用控制基准以及制订工程筹资计划的依据。1.对业主来说，一项建筑设施的成本包括初始投资和随后的运行与养护费用。2.设计者和施工管理者应当非常明确的重要一点是，施工建设费用是成本中最主要的一项费用，但是其他费用也不可忽视。3.在高密度建筑的市区建设一个项目，取得土地的费用是一项主要的成本，而对核电站等这样的大型项目建设，融资成本可能与项目的建造成本基本持平。4.站在业主方的角度看，为了分析项目全寿命周期的成本，对每个建设方案的运行和维护成本进行估计是同样重要的。5.成本估算是项目管理中最重要的环节之一。它在
26、项目建设的不同阶段为项目的成本建立了一条基准线。6.A cost estimate at a given stage of project development represents a prediction provided by the cost engineer or estimator on the basis of available data.7.cost engineering is defined as that area of engineering practice where engineering judgment and experience are utilize
27、d in the application of scientific principles and techniques to the problem of cost estimation,cost control and profitability.Exercises（Translate the following Chinese into English,or English into Chinese）8.In most construction budgets,there is an allowance for contingencies or unexpected costs occu
28、rring during construction.This contingency amount may be included within each cost item or be included in a single category of construction contingency.9.Construction cost constitutes only a fraction,though a substantial fraction,of the total project cost.However,it is the part of the cost under the
29、 control of the construction project manager.10.The required levels of accuracy of construction cost estimates vary at different stages of project development,ranging from ball park figures in the early stage to fairly reliable figures for budget control prior to construction.Exercises（Translate the following Chinese into English,or English into Chinese）
