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1、工程管理专业英语专业9.1第一段Construction planning is a fundamental and challenging activity in the management and execution of construction projects. It involves the choice of technology, the definition of work tasks, the estimation of the required resources and durations for individual tasks, and the identific
2、ation of any interactions among the different work tasks. A good construction plan is the basis for developing the budget and the schedule for work. Developing the construction plan is a critical task in the management of construction, even if the plan is not written or otherwise formally recorded.
3、In addition to these technical aspects of construction planning, it may also be necessary to make organizational decisions about the relationships between project participants and even which organizations to include in a project. For example, the extent which sub-construction will be used on a proje
4、ct is often determined during construction planning. 在施工项目的管理和执行中，施工计划是一项基本的并且具有挑战性的活动。它涉及到技术的选择，工作任务的定义、每一个任务所需资源和维持时间的估算，以及不同 工作任务之间相互作用的识别等工作。一个好的施工计划是制定工作计划和工作进度的基础。确定施工计划是管理当中的一项重要工作，即使这个施工计划不是书面的或其他正式记录的形式。除了施工计划技术层面的问题之外，项目组织关于项目参与方之间的沟通和联系所作出的有管决策也是十分重要的。例如，分包商在一个项目中所承担的范围通常是在施工计划期间决定的。 四 In
5、 developing a construction plan, it is common to adopt a primary emphasis on either cost control or on schedule control as illustrated in Fig. 9-1. Some projects are primarily divided into expense categories with associated costs. In these cases, construction planning is cost or expense oriented. Wi
6、thin the categories of expenditure, a distinction is made between costs incurred directly in the performance of an activity and indirectly for the accomplishment of the project. For example, borrowing expenses for project financing and Project Management for Construction: Construction Planning overh
7、ead items are commonly treated as indirect costs. For other projects, scheduling of work activities over time is critical and is emphasized in the planning process. In this case, the planner insures that the proper precenes among activities are maintained and that efficient scheduling of the availab
8、le resources prevails. Traditional scheduling procedures emphasize the maintenance of task precedences (resulting in critical path scheduling procedures) or efficient use of resources over time (resulting in job shop scheduling procedures). Finally, most complex projects require consideration of bot
9、h cost and scheduling over time, so that planning, monitoring and record keeping mustconsider both dimensions. In these cases, the integration of schedule and budget information is a major concern. In this chapter, we shall consider the functional requirements for construction planning such as techn
10、ology choice, work breakdown, and budgeting. Construction planning is not an activity which is restricted to the period after the award of a contract for construction. It should be an essential activity during the facility design. Also, if problems arise during construction, re-planning is required
11、在制定一项施工计划时，通常在成本控制或进度控制中采用如图9-1所示的主要的重点。一些项目被主要地分为费用类别以及相关成本。在这些情况下，施工计划是成本或费用导向的。在划分支出类别时，我们将对执行一项活动所发生的直接成本和整个项目完成所需的间接成本予以特殊的对待。例如，为 项目融资而产生的借款费用和日常开支项目通常被认为是间接成本。对其他项目来说，制定工作活动随时间的进度是重要的，而且在计划过程中被强调。在这种情况下，施工计划人员遇到的是确保维持各项工作适当的前导关系，保证对各项资源得到有效安排。传统的进度程序强调保持任务前导关系或资源随时间的有效利用。最后，大部分复杂的项目要求同时考虑成本和进
12、度，所以计划、监控和记录必须考虑这两个尺度。在这些情况下，进度和预算信息的综合是一个重要的关注。 9.4第四段Forgetting a necessary precedence relationship can be more insidious. For example, suppose that installation of dry wall should be done prior to floor finishing. Ignoring this precedence relationship may result in both activities being scheduled
13、 at the same time. Corrections on the spot may result in increased costs or problems of quality in the completed project. Unfortunately, there are few ways in which precedence omissions can be found other than with checks by knowledgeable managers or by comparison to comparable projects. One other p
14、ossible but little used mechanism for checking precedences is to conduct a physical or computer based simulation of the construction process and observe any problems. 忘记一个必要的先导关系会有隐伏的危害。例如，设想预制墙的安装应当在地板完成之前进行。忽视这个先导关系会导致这两项活动同时被安排。对这一点的更改会导致成本增加或已完成项目的质量问题。遗憾的是，除了依靠有经验的项目经理进行核对和通过与类似项目进行比较之外，还几乎没有能够
15、发现工作之间先后顺序关系遗漏的有效方法。一种理论上可行但很少使用的核对先导关系的是对施工过程进行计算化的模拟，并从中观察和发现问题。 第五段Finally, it is important to realize that different types of precedence relationships can be defined and that each has different implications for the schedule of activities: Some activities have a necessary technical or physical re
16、lationship that cannot be superseded. For example, concrete pours cannot proceed before formwork and reinforcement are in place. Some activities have a necessary precedence relationship over a continuous space rather than as discrete work task relationships. For example, formwork may be placed in th
17、e first part of an excavation trench even as the excavation equipment continues to work further along in the trench. Formwork placement cannot proceed further than the excavation, but the two activities can be started and stopped independently within this constraint. Some precedence relationships ar
18、e not technically necessary but are imposed due to implicit decisions within the construction plan. For example, two activities may require the same piece of equipment so a precedence relationship might be defined between the two to insure that they are not scheduled for the same time period. Which
19、activity is scheduled first is arbitrary. As a second example, reversing the sequence of two activities may be technically possible but more expensive. In this case, the precedence relationship is not physically necessary but only applied to reduce costs as perceived at the time of scheduling. 最后，还应
20、当认识到，虽然我们定义了不同类型的先导关系，但每一种先导关系对于进度计划而言却有着不同的含义： l 某些活动之间有一个必要的技术上的或物理上的关系是不能被取代的。例如，混凝土的浇筑不能在模板和钢筋安装完成之前进行。 l 某些工作之间的顺序关系是根据工作空间而非工艺流程来确定的。例如，可以在开挖沟槽的第一部分先安装模板，即使开挖装备继续沿着这条沟槽工作。支设模板虽然不能先于沟槽开挖进行，但两项工作可以在不同的施工段上独立进行。 虽然某些先导关系不是技术上必须的，但是是由于施工计划中的隐含的决策。例如，两项工作可能要使用同一台机械设备，这样就必须确定它们之间的先导关系，以便这两项工作不会安排在同一
21、时间段内施工。先安排哪一项工作是任意的。再举个例子，颠倒两个工作的顺序可能在技术上是可行的，但会有较高的成本。在这种情况下，先导关系不是技术上必须的，而是在制定进度计划时被认为仅仅适用于降低成本。 六 In revising schedules as work proceeds, it is important to realize that different types of precedence relationships have quite different implications for the flexibility and cost of changing the cons
22、truction plan. Unfortunately, many formal scheduling systems do not possess the capability of indicating this type of flexibility. As a result, the burden is placed upon the manager of making such decisions and insuring realistic and effective schedules. With all the other responsibilities of a proj
23、ect manager, it is no surprise that preparing or revising the formal, computer based construction plan is a low priority to a manager in such cases. Nevertheless, formal construction plans may be essential for good management of complicated projects 在随着工作的进展对进度计划进行调整时，应当意识到不同类型的先导关系在改变施工计划时灵活性和成本不同。
24、遗憾的是，许多正式的制定进度的系统没有能力指出这种灵活性的类型。结果，作出这些决策以及确保现实可行的和有效的进度计划的重担就落在了项目经理身上。考虑到项目经理其它所有的责任，在这种情况下，准备或修改正式的、基于计算机化的施工计划对于项目经理来说具有较低的优先权就不会令人感到奇怪。然而，正式的施工计划对于很好地管理复杂的项目是必要的。 十.2The most widely used scheduling technique is the critical path method (CPM) for scheduling, often referred to as critical path sc
25、heduling. This method calculates the minimum completion time for a project along with the possible start and finish times for the project activities. Indeed, many texts and managers regard critical path scheduling as the only usable and practical scheduling procedure. Computer programs and algorithm
26、s for critical path scheduling are widely available and can efficiently handle projects with thousands of activities. 使用最广泛的制定进度计划的技术是用关键路线方法编制进度，通常指的是关键线路进度计划。这种方法能够计算出项目的最短完成时间和项目各项活动可能的开始与结束时间。确实，许多测试结果和项目经理都认为关键线路进度计划是唯一有用的和实用的制定进度计划的程序。制定关键线路进度的计算机程序和算法，可以广泛的被利用，而且可以有效地处理拥有成千上万个活动的项目。 There may
27、 be more than one critical path among all the project activities, so completion of the entire project could be delayed by delaying activities along any one of the critical paths. For example, a project consisting of two activities performed in parallel that each require three days would have each ac
28、tivity critical for a completion in three days. 在全部的项目活动当中，可能会有多条关键线路，所以整个工程的完成时间会因为任何一条关键线路上活动的延迟而推后。例如，一个项目由两个同时进行的活动组成，每一项活动都需要三天，则应需要三天来完成个活动的关键线路。 Formally, critical path scheduling assumes that a project has been divided into activities of fixed duration and well defined predecessor relationsh
29、ips. A predecessor relationship implies that one activity must come before another in the schedule. No resource constraints other than those implied by precedence relationships are recognized in the simplest form of critical path scheduling. 正式地，关键线路进度计划假设一个项目被分成多个活动，这些活动有固定的工期而且被很好地确定了前后顺序关系。一个前后顺序
30、关系意味着在进度上一项活动必须在另一项活动之前进行。最简单的关键线路进度计划编制，除了时间先后关系的限制外，没有资源限制 To use critical path scheduling in practice, construction planners often represent a resource constraint by a precedence relation. A constraint is simply a restriction on the options available to a manager, and a resource constraint is a c
31、onstraint deriving from the limited availability of some resource of equipment, material, space or labor. For example, one of two activities requiring the same piece of equipment might be arbitrarily assumed to precede the other activity. This artificial precedence constraint insures that the two ac
32、tivities requiring the same resource will not be scheduled at the same time. Also, most critical path scheduling algorithms impose restrictions on the generality of the activity relationships or network geometries which are used. In essence, these restrictions imply that the construction plan can be
33、 represented by a network plan in which activities appear as nodes in a network, as in Figure 9-6. Nodes are numbered, and no two nodes can have the same number or designation. Two nodes are introduced to represent the start and completion of the project itself. ：为了在实践中使用关键线路进度计划，施工计划制定者经常根据前后顺序关系提出
34、一个资源限制。制约因素就是对可供管理人员选择的一种限制，而资源制约因素来源于某些可用资源，如设备、材料、空间或劳动力。例如，两个活动都需要同一种设备，则其中任意一个活动应在另一个之前进行。人为确定的先后顺序制约确保了两个需要同一资源的活动不被安排在同一时间。另外，大部分关键线路进度计划的算法把限制因素强加给大部分活动之间的关系或所使用的网络图。本质上，这些限制因素意味着施工计划可以由网络图计划表示，在网络图中，节点表示活动。节点都被编上了数字，而且任两个节点不会有相同的数字或指向。两个节点被用来代表项目的开始和完成 十.4Communicating the project schedule i
35、s a vital ingredient in successful project management. A good presentation will greatly ease the managers problem of understanding the multitude of activities and their inter-relationships. Moreover, numerous individuals and parties are involved in any project, and they have to understand their assi
36、gnments. Graphical presentations of project schedules are particularly useful since it is much easier to comprehend a graphical display of numerous pieces of information than to sift through a large table of numbers. Early computer scheduling systems were particularly poor in this regard since they
37、produced pages and pages of numbers without aids to the manager for understanding them.In practice,a project summary table would be much longer .It is extremely tedious to read a table of activity numbers ,durations,schedule .In practice ,producing diagrams manually has been a common prescription to
38、 the lack of automated drafting facilities. 沟通项目进度计划是成功的项目管理中一个至关重要的组成部分。一个好的陈述将会大幅简化项目经理关于理解多数活动以及他们之间关系的问题。甚至，项目中涉及的许多个体和参与方，他们也要理解各自的任务。以图形将项目进度计划显示出来特别有用，因为用大量信息图形表现要比用罗列大量数据的表格容易理解得多。早期的计算机进度计划系统在这方面尤其欠缺，由于它们产生的一页又一页的数据对项目经理理解来说毫无帮助。在实践中，一个项目的汇总表格会非常的长。阅读这样一个表格是极度冗长乏味的，里面有活动的编号、工期、进度计划时间和数据，由此可
39、获得对项目进度计划的理解和鉴定。在实际中，通过手工绘图来应对由于缺少自动绘图设备已经成为一个惯例。 Network diagrams for projects have already been introduced. These diagrams provide a powerful visualization of the precedences and relationships among the various project activities. They are a basic means of communicating a project plan among the pa
40、rticipating planners and project monitors. Project planning is often conducted by producing network representations of greater and greater refinement until the plan is satisfactory. ：项目的网络计划图已经被引入。这些网络图对于不同项目活动之间的先后顺序关系及联系提供了一个强大的可视化。它们是参与编制人员和项目监理沟通项目计划的基本方法。项目计划经常通过绘制越来越精修的网络图表示进行管理直至计划是令人满意的 A us
41、eful variation on project network diagrams is to draw a time-scaled network. The activity diagrams shown in the previous section were topological networks in that only the relationship between nodes and branches were of interest. The actual diagram could be distorted in any way desired as long as th
42、e connections between nodes were not changed. In time-scaled network diagrams, activities on the network are plotted on a horizontal axis measuring the time since project commencement. Figure 10-8 gives an example of a time-scaled activity-on-branch diagram for the nine activity project in Figure 10
43、-4. In this time-scaled diagram, each node is shown at its earliest possible time. By looking over the horizontal axis, the time at which activity can begin can be observed. Obviously, this time scaled diagram is produced as a display after activities are initially scheduled by the critical path met
44、hod. 项目网络图很有用的一种形式就是时标网络图。在先前部分中所展示的活动计划图是拓扑网络图，在这之中，只有节点和连接之间的关系是值得注意的。实际上的图表可以按任意一种想要的方式被画出，只要节点之间的联系没有改变。在时标网络图中，随着项目的展开，活动被放在衡量时间的水平坐标上 11.1 (1)Section 10.3 described the application of critical path scheduling for the situation in which activity durations are fixed and known. Unfortunately, act
45、ivity durations are estimates of the actual time required, and there is liable to be a significant amount of uncertainty associated with the actual durations. During the preliminary planning stages for a project, the uncertainty in activity durations is particularly large since the scope and obstacl
46、es to the project are still undefined. Activities that are outside of the control of the owner are likely to be more uncertain. For example, the time required to gain regulatory approval for projects may vary tremendously. Other external events such as adverse weather, trench collapses, or labor str
47、ikes make duration estimates particularly uncertain. ：10.3部分描述了在工作持续时间是确定的并且已知道的情况下，关键线路进度计划的应用。遗憾的是，活动工期是实际所需时间的估算，并且有许多与实际工期相联系的不确定性。在一个项目的初步计划阶段，由于项目的范围和潜在的障碍还不明确，活动工期的不确定性尤其较大。脱离业主控制的活动也很可能更加不确定。例如，为获得管理机构的批准所需的时间也会变化非常大。此外，恶劣的天气、沟槽塌方或人工罢工等都会使工作持续时间变得极不确定。 (2)Two simple approaches to dealing wit
48、h the uncertainty in activity durations warrant some discussion before introducing more formal scheduling procedures to deal with uncertainty. First, the uncertainty in activity durations may simply be ignored and scheduling done using the expected or most likely time duration for each activity. Sin
49、ce only one duration estimate needs to be made for each activity, this approach reduces the required work in setting up the original schedule. Formal methods of introducing uncertainty into the scheduling process require more work and assumptions. While this simple approach might be defended, it has two drawbacks. First, the use of expected activity durations typically results in overly optimistic schedules for completion; a numerical example of this optimism appears below. Second, the use of single activity duratio
