The Project Life Cycle
　　项目生命期
　　Project managers or the organization can divide projects into phases to provide better management control with appropriate links to the ongoing operations of the performing organization. Collectively, these phases are known as the project life cycle. Many organizations identify a specific set of life cycles for use on all of their projects.
　　项目经理或组织可以把每一个项目划分成若干个阶段，以便有效地进行管理控制，并与实施该项目组织的日常运作联系起来。这些项目阶段合在一起称为项目生命期。许多组织识别出一套具体的生命期供其所有的项目使用。
　　Characteristics of the Project Life Cycle
　　项目生命期的特征
　　The project life cycle defines the phases that connect the beginning of a project to its end. For example, when an organization identifies an opportunity to which it would like to respond, it will often authorize a feasibility study to decide whether it should undertake the project. The project life cycle definition can help the project manager clarify whether to treat the feasibility study as the first project phase or as a separate, stand-alone project. Where the outcome of such a preliminary effort is not clearly identifiable, it is best to treat such efforts as a separate project.
　　项目生命期确定了将项目的开始和结束连接起来的阶段。例如，当某个组织发现一个可以考虑和利用的机会时，它通常会责成有关人员进行可行性研究，以决定该项目是否值得立项。项目生命期的定义有助于项目经理弄清是否应将该项可行性研究视为项目的第一个阶段，或者将其当做一个单独的项目。当这种初步努力的结果无法识别清楚时，最好将其当做单独的项目进行处理。
　　The transition from one phase to another within a project's life cycle generally involves, and is usually defined by, some form of technical transfer or handoff. Deliverables from one phase are usually reviewed for completeness and accuracy and approved before work starts on the next phase. However, it is not uncommon for a phase to begin prior to the approval of the previous phase's deliverables, when the risks involved are deemed acceptable. This practice of overlapping phases, normally done in sequence, is an example of the application of the schedule compression technique called fast tracking.
　　从项目生命期的一个阶段转到另一阶段通常是某种形式的技术交接，这种阶段转移通常也由这种技术交接确定。前一阶段产生的可交付成果通常要接受是否已经完成和准确的审查，在验收之后才能开始下一阶段的工作。但是，如果认为所涉及的风险是可以接受的话，后一阶段可以在前一阶段可交付成果通过验收之前开始。通常这种将按照先后顺序完成的两个阶段重叠的做法，是应用所谓快速跟进进度压缩技术的一个例子。
　　There is no single best way to define an ideal project life cycle. Some organizations have established policies that standardize all projects with a single life cycle, while others allow the project management team to choose the most appropriate life cycle for the team's project. Further, industry common practices will often lead to the use of a preferred life cycle within that industry.
　　目前没有确定项目生命期的惟一最好办法。某些组织的既定方针是用一个项目生命期作为标准的方式处理所有的项目，而另外一些单位则允许项目管理团队为其项目选择最适合的项目生命期。另外，行业的通用做法经常造成本行业内部使用某种约定俗成的项目生命期。项目生命期的定义还将确定项目开始与结束时的哪些过渡行动应包括在项目范围之内，哪些则不应包括在内。这样，就可以用项目生命期的定义把项目和项目实施组织持续的日常运作业务联系在一起。
　　Project life cycles generally define:
　　项目生命期通常规定：
　　What technical work to do in each phase （for example, in which phase should the architect's work be performed?）
　　项目的各个阶段应当从事何种技术工作（例如，建筑师的工作应放在项目的哪个阶段完成）。
　　When the deliverables are to be generated in each phase and how each deliverable is reviewed, verified, and validated
　　项目各阶段可交付成果应何时生成，以及如何审查、核实和确认。
　　Who is involved in each phase （for example, concurrent engineering requires that the implementers be involved with requirements and design）
　　项目各阶段由哪些人员参与（例如，并行工程要求实施人员参与制定要求说明书和设计）。
　　How to control and approve each phase.
　　如何控制和批准项目各个阶段。
　　Project life cycle descriptions can be very general or very detailed. Highly detailed descriptions of life cycles can include forms, charts, and checklists to provide structure and control.
　　说明项目生命期时可以十分笼统，也可以非常详细。非常详细的说明可以包括许多表格、图表和核对表，使其条理清楚，便于控制。
　　Most project life cycles share a number of common characteristics:
　　大多数项目生命期的说明具有若干共同特点：
　　Phases are generally sequential and are usually defined by some form of technical information transfer or technical component handoff.
　　项目阶段一般按顺序首尾衔接，通常根据某种形式的技术信息传递或技术部件交接来确定。
　　Cost and staffing levels are low at the start, peak during the intermediate phases, and drop rapidly as the project draws to a conclusion. Figure 2-1 illustrates this pattern.
　　人力投入和费用，开始时低，随之增高，在项目接近收尾时迅速下降。这种模式如图2-1所示。


　　Figure 2-2. Stakeholders' Influence Over Time

　　图2-2利害关系者影响随着时间的变化

　　The level of uncertainty is highest and, hence, risk of failing to achieve the objectives is greatest at the start of the project. The certainty of completion generally gets progressively better as the project continues.
　　项目开始时，成功地完成项目的可能性最低，因此风险和不确定性最高。随着项目继续绩效，成功地完成项目的可能性通常都逐渐上升。
　　The ability of the stakeholders to influence the final characteristics of the project's product and the final cost of the project is highest at the start, and gets progressively lower as the project continues. Figure 2-2 illustrates this. A major contributor to this phenomenon is that the cost of changes and correcting errors generally increases as the project continues.
　　项目开始时，项目利害关系者对项目产品最后特点和项目最后成本的影响力最强，而随着项目的绩效，这种影响逐步减弱。图2-2形象地说明了这一点。造成这种现象的主要原因是随着项目的绩效，变更计划和纠正失误的代价通常与日俱增。　　


　　Figure 2-2. Stakeholders' Influence Over Time

　　图2-2利害关系者影响随着时间的变化

　　Although many project life cycles have similar phase names with similar deliverables, few life cycles are identical. Some can have four or five phases, but others may have nine or more. Single application areas are known to have significant variations. One organization's software development life cycle can have a single design phase, while another can have separate phases for architectural and detailed design. Subprojects can also have distinct project life cycles. For example, an architectural firm hired to design a new office building is first involved in the owner's definition phase while doing the design, and in the owner's implementation phase while supporting the construction effort. The architect's design project, however, will have its own series of phases from conceptual development, through definition and implementation, to closure. The architect can even treat designing the facility and supporting the construction as separate projects, each with its own set of phases.
　　尽管许多项目生命期具有彼此相似的阶段名称，所要求的可交付成果名称也极其相似，但其内容绝少雷同。某些项目有4个或5个阶段，但另一些项目可多达9个阶段以上。即使在某单一应用领域内，也会有很大差别，如一个组织的软件开发生命期可能只有一个设计阶段，而另一个组织却可能将其分为功能设计和详细设计两个单独的阶段。项目内的子项目也可以有明显的项目生命期。例如，一家建筑师事务所受雇为他人设计新办公楼时，首先在设计时参与了业主的设计要求制定阶段，随后又在协助施工时参与了业主的实施阶段，协助施工。但建筑师本身的设计项目也有自己的一系列阶段，包括项目构思、要求制定、实施，直至项目收尾。这位建筑师甚至可以把办公楼的设计和对施工的协助视为两个不同的项目，分别包括各自的明显阶段。