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1、如有侵权，请联系网站删除，仅供学习与交流交通运输与物流专业英语(Unite 6)中英文【精品文档】第 6 页Unit Six Alternative Evaluation and ChoiceText A Feasibility determinationEvery decision involves at least two options. Even though a single proposal was presented, decision makers have a choice between the proposal and doing nothing. Evaluation
2、appraises the positive impacts and the negative impacts of alternative options in terms of either a single or multiple decision criteria. Determining relevant impacts to particular decision and specifying the appropriate decision criteria are related to the value system within which the choice is to
3、 be made. In the case of transportation decisions in the public sector, the operating value system is not that of any single individual or subgroup but that of the community as a whole. There exist conflicting value systems within society. Consequently, transportation decision also entails the resol
4、ution of conflicts.每一项抉择至少包含两个选项，即使是一个单一的提议，决策者也可以选择执行这个提议或什么也不做。不管是根据单一的还是多样化的决策标准，评估的目的在于评价每个选项的积极影响和消极影响。（人们）在做决定时，确立具体抉择的相关影响并详细说明合理的评判标准与其价值体系是相关联的。在公共部门的交通决策中，其价值体系代表的不仅是某一个人或小团体的利益，而是整个社区的价值体系。社会中常存在着相互冲突的价值体系，因此，交通决策也包含着解决（价值冲突）的问题。Two types of evaluation studies are commonly undertaken: pre
5、-implementation studies, which facilitate the choice of the best course of action from among several alternative proposals, and post-implementation studies, which assess the performance of already implemented action. Post-implementation studies are important for two reasons. First, they help to disc
6、over whether or not the implemented alternative performs well, and second, they help to determine whether or not it continues to perform properly over time. This is especially important in the case of transportation systems, which are subject to changing conditions and also to evolving goals and obj
7、ectives. Continuous monitoring and periodic performance evaluation can help identify emerging problems and also provide guidance to the design of possible improvements.（交通决策中）通常存在着两种类型的评估调查：实施前调查，这有助于在几种备选方案中选出最佳方案；实施后调查，用于评估实施项目的各项性能指标。实施后调查非常重要，原因有二：第一，它有助于发现实施项目是否运行良好；第二，它有助于确定（实施项目）随着时间流逝仍然能良好运行
8、。在易受条件、目标和目的改变影响的交通运输系统中，（实施后调查）显得尤为重要。持续的监测和周期性的性能评估有助于发现问题，为可能的改进设计提供帮助。An alternative must be both feasible and superior to all others in order to be selected for implementation. The prerequisites to the admission of an alternative to the list of acceptable options include the conditions of techn
9、ological feasibility, economic efficiency, and cost-effectiveness, and availability of the needed resources. We present the fundamental elements of efficiency and effectiveness evaluation techniques, along with brief description of their conceptual foundations and their major strengths and weaknesse
10、s.用于实施的选择方案必须具有可行性且优于其他备选方案。（项目中）能够进入候选名单的方案必须包括：技术可行性条件、经济效率、成本效率以及资源可得性。我们举出了一些基础的与效率和有效性相关评估技术指标，简单地描述了它们的概念和各自的优缺点。Feasibility Technological feasibility refers to the ability of a system to function according to the laws of nature and not to its desirability: A perpetual-motion machine may be hi
11、ghly desirable but technologically impossible. Engineers and other technologists are qualified to deal with questions relating to technology. Research and development are on-going activities that occasionally lead to technological breakthroughs. The vast majority of practical applications, however,
12、involve the use of existing technology. Even then, innovative and creative ways of combining off-the-shelf technology are common. Consequently, the question of technological feasibility is an aspect of evaluation that cannot be ignored.技术可行性指的是在遵循自然规则的条件下系统能展现出的性能，它排除了不切实际的幻想，例如，人们都渴望（发明）永动机，但在技术上这是
13、不可能做到的。工程师和技术人员的职责在于处理与技术相关的问题，持续不断的研发偶尔能够实现技术上的突破，然而在大量的实践应用中使用的仍然是现存的技术。尽管如此，将创新方法与现存技术相结合仍然普遍使用，因此，技术可行性问题是评估过程中不可忽视的一个方面EfficiencyEfficiency is defined as the ratio of the quantity produced (output) to the resources required for its production (input). Physical or machine efficiency is the ratio
14、 of the energy delivered by a machine or a process to the energy supplied to it. Although expressed in the same unit of measurement, the input and the output energy differ in form, for example, energy in the form of electricity vis-vis energy in the form of work done by the system. Machine efficienc
15、y is always less than unity because of the unavoidable energy losses that are incurred n the process. This waste can be justified only when the usefulness, or utility, of the output exceeds that of the input. When both the numerator and the denominator are converted to the same measure of economic v
16、alue, their ratio is referred to as the economic efficiency of the machine, which must be greater than unity if the machine is to be economically feasible. The idea of economic efficiency has been extended to the evaluation of systems to contrast the economic value of the advantages (or benefits) th
17、at are derived from the system to its disadvantages (or costs).效率指的是产出量（输出）与生产所需资源（输入）之比。机械效率指的是一台机器能量输出比率或做功功率。尽管（输出和输入）在同一测量单位上体现，但输出能量和输入能量在形式上截然不同，例如，一个系统中的能量以电力和做功的形式同时存在。在运行过程中由于不可避免的损失机械效率总是低于100%，而损失的能量只有在输出价值大于输入价值时才有评价的意义。当输出与输入转化为具有相同经济价值的等价物时，输出与输入的比率指的是机器的经济效率，只有当比率大于1时可以说这种机器在经济上具有可行性。
18、经济效率的观点已经推广到系统评价中以对比其所创造的经济价值和成本EffectivenessEffectiveness is defined as the degree to which an action accomplishes tis stated objectives. It differs from efficiency in that it need not have to explicitly express all impacts in the same scale of measurement. For example, the effectiveness of a regio
19、nal transportation system for elderly and handicapped persons may be expressed as the proportion of eligible users that live within the service area of the system or as the total number of persons served, whereas its operation cost may be expressed in terms of dollars. Cost-effectiveness evaluation
20、is the attempt to determine the efficacy of alternatives by comparing their cost to their effectiveness. Of course, if and objective method for collapsing all impacts to the same dimension were available, efficiency and effectiveness would lead to identical results, but no such method exists. Conseq
21、uently, both evaluative methods are used, sometimes separately and sometimes in combination.效果定义为一项行动达到其规定目标的程度。它和效率的不同之处在于，不需要用同一测量标准来清晰地表示所有的影响，例如，某一区域内交通运输系统对老年人和残疾人的服务效果可定义为，生活在系统服务区享受到服务的人的比率或者享受到服务的全部人口数量，然而系统运行的成本却是以美元计量的。成本效益评估旨在通过比较成本和效益确定各项方案的效能。当然，如果存在一种客观的方法可以将所用影响效果转化为同一种度量标准，那么评估效果和效率得
22、到的是完全相同的结果，但是这样的方法不可能存在，因此，这两种方法都有各自的用途，有时会单独使用，有时则一起使用。AffordabilityAn alternative may be technologically feasible, economically efficient, and cost-effective and yet not be a prudent choice for implementation. Problems of affordability of the financial and other resources that are needed for its i
23、mplementation. Problems of affordability or resource availability are not uncommon. Consider, for example, the case of financial resources. Usually, there exists a lag between the time when financial resources are expended and the time when the returns of the investment are realized. Lack of access
24、to financial resources during this critical time lag would render the investment infeasible. Another common problem of financial affordability that is especially true in the case of public projects is related to the fact that the benefits derived by a public investment do not usually return in the f
25、orm of money to the agency that expends the financial costs for the project. Unless the agency is in a position to afford these expenditures, it would not produce the benefits for whomever they would otherwise accrue. 有时一项方案可能满足技术可行性、经济效率、成本效率等标准，但它仍然不算一个精明的选择，因为这项方案可能在实施过程中缺乏必需的资金和资源。资源可得性的问题非常常见，比
26、如资金缺乏。通常，资金的投资和回收存在一个时间的滞后性，资金缺乏在严重的时间滞后中会造成投资无法进行。另一个资金可得性的常见问题（尤其是在公共项目中）是，公共投资所得的收益通常不会以现金的形式返回到投资该项目的机构，除非该机构必须处于支持这些花费的地位，否则这项投资不会因为（投资的积累）产生任何收益。Text B Further evaluationDetermining the feasibility of each alternative is only half of the evaluation process. The other half involves the comparis
27、on of all proposals (including the do nothing alternative) in order to select the best one among them. Based on the assignment of relative weight to the impacts of each alternative, this step involves impact trade-offs. Consider, for example, a choice between two transportation alternative requiring
28、 equal and available financial expenditures. Further, assume that one of the two would provide a higher level of mobility than the other but would also discharge higher quantities of atmospheric pollutants. This statement implies that three impacts have been identified as relevant to the choice, tha
29、t appropriate measures of performance have been established to express them, and that the likely levels of these impacts have been predicted for each alternative, perhaps using the methods in the previous chapters. When comparing the two alternatives, a trade-off between mobility on one hand and env
30、ironment quality on the other becomes apparent. In the final analysis, the evaluation method used to aid this decision must incorporate the assignment of relative weights to impacts.确定每种方案的可行性只是整个评估过程的一半，另一部分包括了比较各方案（包括什么都不做在内）从而选出最佳方案。每种方案的作用效果基于相对权重的分配而定，因此（决策人员）面临着权衡取舍的问题，设想这样一个例子，在两种资金花费相同的交通运输方
31、案中做出选择，更进一步，如果其中一种方案具有更高的灵活性，但是会排放更多的大气污染物（此时该如何选择）。以上示例中包含了三个与抉择有关的影响，对于每一种影响都已建立起了适当的方法用于表述它们，使得每一种方案都可用相应的影响级别进行预测，（预测过程中）可能就会用到先前章节中提到的方法。当比较（以上）两种方案时，如果灵活性和环境质量问题都变得无法忽视时就会面临取舍的问题，在最终分析阶段，用于决策的评估方法就会结合各项影响的权重来考虑。The foregoing example of evaluation raises a problem that is inherent in situations
32、 where the decision makers are faced with multiple decision criteria. On the side of costs, the direct cost of operating the system and negative externality (e.g., the unintended undesirable impact of air pollution) were identified. Direct benefits (i.e., mobility) and potential positive externaliti
33、es are typically included in the evaluative calculus. All recognizable impacts (e.g., advantages or benefits) and negative impacts (i.e., disadvantages or costs) and the results of the impact estimation process that precedes the evaluation phase may be summarized in an impact matrix, as illustrated
34、in table 6-1.前面的评估示例提出当决策者面临环境中多个决策指标时存在一个内在的问题，关于成本，系统运行和消极外部效应的直接成本（如始料未及的空气污染问题）是明确的，而直接收益（如流通性）和潜在的积极外部效应通常需要通过评估性的计算得到。所有获得认可的影响（优点或收益）和负面影响（缺点或费用），以及在评估阶段进行的对影响结果的估计过程可以概括在一个影响矩阵中。如表6-1所示。This array lists the estimated impacts associated with each alternative expressed in terms of the applicab
35、le measures of performance, which differ with regard to their units of measurement. Moreover, some are expressed in terms of quantitative measures (i.e., carbon monoxide concentration), and others are qualitative.表中列出了每种方案以适当的性能测量方法（有别于其测量单位）表示的影响评估值。其中一些属于定量方法，另外的属于定性方法。Some criteria were selected
36、to measure the performance of alternative transit systems for comparison purpose. They are availability and coverage, average trip time, service reliability, rider convenience, rider comfort, system patronage, system capacity, consumption of land, displacement of residents, displacement of business,
37、 disruption from construction activities, saving in energy, technical risk, support regional development, support community development, reduction of air pollution, noise level, visual intrusion, vistas, historical sites, reduction of accident exposure, security, total annual cost, cost per trip, be
38、nefit-cost ratio, and so on.其中一些标准用于测量方案运输系统的性能以进行比较，包括可得性、覆盖范围、平均出行时间、服务可靠性、正点率、行驶的舒适度、系统容量、系统能力、土地利用率、居民迁移、商业转移、社区福利设施的减少、能源节约、技术风险、支持区域发展、支持社区发展、空气污染减少、噪音等级、视觉干扰、景观、历史遗址、事故减少、安全、总的年均成本、平均出行成本、成本收益率等。The generalized impact matrix includes the direct and indirect impacts of each alternative either in quantitative terms or qualitative terms.每种方案的影响从定性与定量的角度可归纳为一个影响矩阵，其中包括直接影响和间接影响。