CHAPTER 12 Capacity and Level-of-Service Analysis for Freeways and Multilane Highways
12 章 对多车道公路和高速公路的通行能力和水平式服务的分析

  12.1 Introduction to Capacity and Level-of-Service Concepts
  12.1 介绍通行能力和水平式服务的概念
One of the most critical needs in traffic engineering is a clear understanding of how much traffic a given facility can accommodate and under what operating conditions. These important issues are addressed in highway capacity and level-of-service analysis.
在交通工程中最关键的需求之一是对在一定工作条件下有多少交通设施可以容纳 有着清醒的认识。这些重要问题能对公路的通行能力和水平式服务分析进行处理。
The basis for all capacity and level-of-service analysis is a set of analytic procedures that relate demand or existing flow levels, geometric characteristics, and controls to measures of the resulting quality of operations. These models take many forms. Some are based on regression analysis of significant data bases. Some are based on theoretical algorithms and/or laws of physics. Still others are based on the results of simulation. Their application allows traffic engineers to determine the ultimate traffic-carrying ability of a facility and to estimate operating characteristics at various flow levels.
所有的能力和水平式服务分析的基础是一个分析程序中有关的要求或现有的流量 水平,几何特征,以及由此产生的业务质量的措施控制设置。这些模型采取多种形式。 有些是基于回归分析的重要数据基础。有些是基于理论算法和/或物理定律。还有一些 是根据模拟的结果。 他们的应用程序允许交通工程师用以确定最终的交通设施承载能力 和估计各种流水平运行的特点。
The U.S. standard for these types of analyses is the Highway Capacity Manual (HCM), a publication of the Transportation Research Board (TRB) of the National Academy of Engineering. Its content is controlled by the Committee on Highway Capacity and Quality of Service (HCQSC) of the TRB. The development of material
for the manual is supported by a number of federal agencies through funding for basic and applied research. These agencies include the National Cooperative Highway Research Program (NCHRP) and the Federal Highway Administration (FHWA).
对于这些类型的分析美国的标准是道路通行能力手册(HCM),这是由美国国家 工程院的一个运输研究委员会(TRB)出版的。该手册是由联邦机构通过对若干基础和 应用研究的经费所支持的。这些机构包括国家合作公路研究计划(NCHRP)和联邦公路 管理局(联邦公路管理局)。
The first edition of the HCM [1] was published by the then Bureau of Public Roads in 19
  50. Its objective was to provide uniform guidelines for the nation's rapidly growing .Highway construction program. The informal group of Bureau personnel that developed the first edition became the founding members of the HCQSC. The second edition [2] was published in 19
  65.It introduced significant new material on limited access facilities, as well as the level-of-service concept. The third edition [3] was published in 1985, providing refinements to the level-of-service concept and adding material on pedestrian and transit facilities. Introduced for the first time as a loose-leaf document, significant updates to this edition were introduced in 1994 [4] and 1997 [5].
美国道路通行能力手册第一版由当时的公共道路局于 1950 年出版的。 其目的是 为了指引国家的快速发展。此公路建设项目的工作人员成为发达国家的 HCQSC 的创始 成员。第二版发表于 19
  65.它介绍了在通道设施的重要的新材料,以及水平式服务的概 念。第三个版本于 1985 年出版,提供优化的水平式服务的概念与行人和交通设施新添 加的材料。对第一次推出的活页文件的说明,在 1994 年的第四版和 1997 年的第五版 有了新的改进。
The material in this text is based on the fourth edition of the HCM [6], published in December of 20
  00.Often referred to as, this edition added significant new material on planning applications and corridor and system analysis. It also formally addressed the issue of simulation and its relationship to traditional deterministic highway capacity and level of service models.
第六版的文字材料是基于美国道路通行能力手册第四版。它是在 2000 年 12 月 出版的,它指的是 HeM20
  00。这个版本添加了关于走廊和系统分析的新材料。这也正 式解决了模拟与传统的确定性的公路通行能力和服务模式层面的问题。
The HCM 2000 is also the first manual to be published in two forms: one in standard U.S. units, the other in metric units. The manual was originally developed in metric units in response to legislation requiring all states to convert to a metric system. Late in the development of HCM 2000, the legislation was modified, leaving a split among state highway and transportation departments. As a result, some states now use a metric system, while others have maintained or have returned to standard U.S. units.
2000 年版本的美国道路通行能力手册也是第一份将以两种形式公布的手册:一 种是美国标准单位,一种是公制单位。该手册最初是在回应立法,要求所有国家要转换 为公制计量单位。在以后的美国道路通行能力手册中,法律进行了修改,导致了国家 公路和运输部门的分裂。因此,一些国家现在使用公制系统,而其他的仍坚持使用美国 的标准单位。
This text is presented primarily in standard U.S. units. As the two versions of the HCM 2000 reflect "hard conversion" between the two sets of units, presentation of both forms in this text would have been impractical.
这主要是在文字体现了美国的标准单位,截至 2000 年的美国道路通行能力手册 在“硬转换”两个单位之间,这两种形式在这个文本将是不切实际的。
A recent paper by Kittelson [7] provides an excellent history and discussion of the development of the HCM and its key concepts.
按 Kittelson 第七版最近的一篇文章提供了一个极好的历史以及在美国道路通行 能力手册的关键概念的发展进行讨论。

  1.1 'The Capacity Concept
  1.1'通行能力的概念 The HCM 2000 defines capacity as follows: The capacity of a facility is the maximum hourly rate at which persons or vehicles reasonably can be expected to traverse a point or a uniform section of a lane or roadway during a given time period under prevailing roadway, traffic, and control conditions. (HCM 2000, pg. 2-
2000 的美国道路通行能力手册定义的通行能力如下: 可合理预期根据当时在穿越道路, 交通和控制条件给定的时间内一个点或一个车道或道 路变截面中,一个设施的容量是每小时速率最高的人或车辆。 (美国道路通行能力手册 2000 年。 2-
The definition contains a number of significant concepts that must be understood when applying capacity analysis procedures:
? Capacity is defined as a maximum hourly rate. For most cases, the rate used is for the peak 15 minutes of the peak hour, although HCM 2000 allows for some discretion in selecting the length of the analysis period. In any analysis, care must be taken to express both the demand and the capacity in terms of the same analysis period.
?通行能力定义了最大时速。对于大多数情况下,速度是高峰的每小时 15 分钟的峰 值,虽然 2000 年的美国道路通行能力手册是在一些选择的分析时间的长短决定的。 在任何分析时,必须小心表达双方的需求和在同一时期分析方面的能力。
? Capacity may be expressed in terms of persons or vehicles. This is critical when transit and pedestrian issues are considered, as well as in the consideration of high-occupancy vehicle lanes and facilities, where the person-capacity is clearly more important than the vehicle-capacity.
?通行能力可能表示的是人或车辆。交通和行人的问题被认为是关键的问题,以及在 车辆通道和设施的问题,这里的人的通行能力显然比车的重要。
? Capacity is defined for prevailing roadway, traffic, and control conditions. Roadway conditions refer to the geometric characteristics of the facility, such as the number of lanes, lane widths, shoulder widths, and free-flow speeds. Traffic conditions refer primarily to the composition of the traffic stream, particularly the presence of trucks and other heavy vehicles. Control conditions refer primarily to interrupted flow facilities, where such controls as STOP and YIELD signs and traffic signals have a significant impact on capacity. The important concept is that a change in any of the prevailing conditions causes a change in the capacity of the facility.
?通行能力是指道路,交通和控制的情况。道路的条件是指该设施的几何特征,如 车道,车道宽度,肩宽度和自由流动速度的数量。交通条件主要指的交通流,特别是卡 车和其他重型车辆的存在组成。控制条件主要指断流设施,在那里停车避让标志和交通 信号控制等能力有重大影响。其重要思想是,在目前的状况的任何变化会导致该设施容 量的变化。
? Capacity is defined for a point or uniform section of a facility. This correlates to the "prevailing conditions" discussed above. A "uniform section" must have consistent prevailing conditions. At any point where these conditions change, the capacity also changes.
?通行容量定义为一个点或一个统一的部分设施。与此相关的“通行条件”上面已 在讨论。 “统一部分”必须有一致的通行条件。在任何一刻,这些条件的改变,也改 变了通行能力。
? Capacity refers to maximum flows that can reasonably be expected to traverse a section. This recognizes that capacity, as are all traffic factors, is subject to variation in both time and space. Thus, capacity is not defined as the single highest flow level ever expected to occur on a facility. Rather it is a value that represents a flow level that can be reasonably achieved repeatedly at a given location and at similar locations throughout the United States. Thus, isolated observations of actual flows in excess of stated capacities is not a contradiction and is, in fact, an expected condition.
?最大通行能力是指可合理预期的流动。此时通行能力是交通的因素,是受时间和 空间变化。因此,通行能力不定义为最高流量将发生时一个设施的水平。相反,它是一
个值,表示一个流动的合理水平,可以实现在一个给定的位置,并在美国各地的类似场 所的反复。因此,这与孤立的观察并不矛盾,在事实上,这是预期的情况。
It should be noted that, while capacity is an important concept, operating conditions at capacity are generally quite poor, and it is difficult (but not impossible) to maintain capacity operation without breakdowns for long periods of time. \
应当指出,虽然通行能力是一个重要的概念,在条件比较差的情况下,这是困难的 (但不是不可能)维持无故障长时间运作能力。

  1.2 The Level-of-Service Concept The level-of-service concept was introduced in the 1965 HCM as a convenient way to describe the general quality of operations on a facility with defined traffic, roadway, and control conditions. Using a letter scale from A to F, a terminology for operational quality was created that has become an important tool in communicating complex issues to decision-makers and the general public. The HCM 2000 defines level of service as follows:

  1.2 水平式服务理念
水平式服务的概念是在 1965 年美国道路通行能力手册 介绍了作为一个便捷的 方式来描述一个具有明确的交通,道路,设施和控制条件的行动的总体质量。使 用字母从 A 到 F 的规模,以运行质量建立术语,已成为一个决策者和公众对复 杂的问题进行交流的重要工具。在 2000 年美国道路通行能力手册 的服务水平定 义如下: "Level of service (LOS) is a quality measure describing operational conditions within a traffic stream, generally in terms of such service measures as speed and travel time, freedom to maneuver, traffic interruptions, and comfort and convenience." (HCM 2000, pg. 2-
“服务级别(LOS)的描述是一个质量的衡量标准在交通流的操作条件,作为一般的 速度和旅行时间,自由行动,交通中断,舒适和便利服务等方面的措施。” (美国道 路通行能力手册 2000 年。2-
The six defined levels of service, A-F, describe operations from best to worst for each type of facility. When originally defined, models did not exist for the prediction of precise quality measures for many types of facilities. This is no longer true. Every facility type now has levels of service defined in terms of a specific measure of effectiveness. Table
  12.1 shows the measures used



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