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 2-1. Typical Project Cost and Staffing Level Across the Project Life Cycle

　　图2-1项目费用与人力投入水平在项目生命期中的典型分布