Highway Capacity Manual 2010 2.HCM PURPOSE AND SCOPE PURPOSE AND OBJECTIVES ociate indicators asures and ervic The objectives of the HCM are to 2.Provide methodologies for estimatingand predicting performance measures,and 3.Explain methodologies at a level of detail that allows readers to understand the factors affecting multimodal operation. The HCM2010 presents the best av vailable techniques at the time s not establish cti owever,it do INTENDED USE The HCM is intended to be used pr the as listed methodologies operations design,preliminary engnein .Travel modes:automobile(and other motorized vehicles),pedestrian,and bicycle,plus transit when it is part of a multimodal urban street facility. Spatial coverae:points,segments,and facilities. .Temporal coverage:undersaturated and oversaturated conditions. TARGET USERS The HCM is prepared for use by (a)engineers who work in the field of traffic operations or highway geometric design and (b)transportation planners who work in the field of transportation system management.To use the manual effectively and to apply its methodd logies,some te chnical ba kground is yinorchcubli The HCM is also useful to management personnel,educators,air quality specialists,noise specialists,elected officials,regional land use planners,and interest groups representing special users. HCM Purpose and Scope Page 1-2
Highway Capacity Manual 2010 2. HCM PURPOSE AND SCOPE PURPOSE AND OBJECTIVES The purpose of the HCM is to provide a set of methodologies, and associated application procedures, for evaluating the multimodal performance of highway and street facilities in terms of operational measures and one or more quality‐of‐ service indicators. Quality of service describes how well a transportation facility or service operates from the traveler’s perspective. The objectives of the HCM are to 1. Define performance measures and describe survey methods for key traffic characteristics, 2. Provide methodologies for estimating and predicting performance measures, and 3. Explain methodologies at a level of detail that allows readers to understand the factors affecting multimodal operation. Level of service is the A-F stratification of quality of service. The HCM 2010 presents the best available techniques at the time of publishing for determining capacity and LOS. However, it does not establish a legal standard for highway design or construction. INTENDED USE The HCM is intended to be used primarily for the analysis areas listed below, to the extent that they are supported by the individual analysis methodologies. • Levels of analysis: operations, design, preliminary engineering, and planning. • Travel modes: automobile (and other motorized vehicles), pedestrian, and bicycle, plus transit when it is part of a multimodal urban street facility. • Spatial coverage: points, segments, and facilities. • Temporal coverage: undersaturated and oversaturated conditions. TARGET USERS The HCM is prepared for use by (a) engineers who work in the field of traffic operations or highway geometric design and (b) transportation planners who work in the field of transportation system management. To use the manual effectively and to apply its methodologies, some technical background is desirable—typically university‐level training or technical work in a public agency or consulting firm. The HCM is also useful to management personnel, educators, air quality specialists, noise specialists, elected officials, regional land use planners, and interest groups representing special users. HCM Purpose and Scope Page 1-2 Chapter 1/HCM User’s Guide December 2010
Highway Capacity Manual 2010 3.STRUCTURE OVERVIEW ch Pr dolog To keep s part HCM at a m vet in 1.Concepts, 2.Uninterrupted Flow, 3.Interrupted Flow,and 4.Applications Guide. When the HCM(was being developed,weremoving toward compliance with the HC e the fed on requirer d to U.S.custor and mosinversion guide is provided latern this The following sections describe the contents of each HCM 2010 volume. VOLUME 1:CONCEPTS VOLUME 1上CONCEPTS tvethe basicinformation that an ay Appl ingcapacity or quality-of-service analys yConcepts s:the of tools atin vailabletopetogalhetie the HCM.Chap er 8 HCM Primer,provides an executive summary of the HCM for decision makers. htw mat nd ele ree-ring material as new najor updates VOLUME 2:UNINTERRUPTED FLOW MOLUME 2:UNINTERRUPTED FLOW Volume 2 contains the methodological chapters relating to uninterrupted- flow system elements.All of the material necessary in performing an analysis of one of these elements appears here:a description of the process thorough enough to allow an analyst to understand the steps involved(although not necessarily replicate them by hand),the scope and limitations of the methodology,specific default values,LOS thresholds,and guidance on special cases and the use of have alternative tools The freeway chapters are pr nted first.arranged from the facility level down to the segment level;the chapters for multilane and two-lane highways Page 1-3 Structure
Highway Capacity Manual 2010 3. STRUCTURE OVERVIEW Since 2000, more than $5 million in funded National Cooperative Highway Research Program (NCHRP) research has partially or entirely focused on HCM methodologies. To keep the HCM at a manageable size and yet incorporate the results of this research, the HCM 2010 has been divided into four volumes: 1. Concepts, 2. Uninterrupted Flow, 3. Interrupted Flow, and 4. Applications Guide. When the HCM2000 (4) was being developed, U.S. states were moving toward compliance with federal requirements to use metric units in the design of roadways. As a result, the HCM2000 was published in “U.S. customary” and “metric” versions. Because the federal metrication requirements were later dropped and most states returned to U.S. customary units, this edition only uses U.S. customary units. A metric conversion guide is provided later in this chapter. The following sections describe the contents of each HCM 2010 volume. VOLUME 1: CONCEPTS VOLUME 1: CONCEPTS 1. HCM User’s Guide 2. Applications 3. Modal Characteristics 4. Traffic Flow and Capacity Concepts 5. Quality and Level-of-Service Concepts 6. HCM and Alternative Analysis Tools 7. Interpreting HCM and Alternative Tool Results 8. HCM Primer 9. Glossary and Symbols Volume 1 covers the basic information that an analyst should be familiar with before performing capacity or quality‐of‐service analyses. Its chapters cover the organization of the HCM; the kinds of applications that can be performed with the HCM; modal characteristics; traffic flow, capacity, and quality‐of‐service concepts; the range of tools available to perform an analysis; guidance on interpreting and presenting analysis results; and the terms and symbols used in the HCM. Chapter 8, HCM Primer, provides an executive summary of the HCM for decision makers. Chapter 8 serves as an executive summary of the HCM for decision Users makers. familiar with the HCM2000 will find that Volume 1 incorporates Part I of the HCM2000; conceptual material from HCM2000 Parts II, IV, and V; and new material developed for the 2010 edition. Volume 1 is provided in three‐ring binder and electronic formats, to facilitate the addition of new conceptual material as new research is incorporated into the HCM between major updates. VOLUME 2: UNINTERRUPTED FLOW 10. Freeway Facilities 11. Basic Freeway Segments 12. Freeway Weaving Segments 13. Freeway Merge and Diverge Segments 14. Multilane Highways 15. Two-Lane Highways VOLUME 2: UNINTERRUPTED FLOW Volume 2 contains the methodological chapters relating to uninterrupted‐ flow system elements. All of the material necessary in performing an analysis of one of these elements appears here: a description of the process thorough enough to allow an analyst to understand the steps involved (although not necessarily replicate them by hand), the scope and limitations of the methodology, specific default values, LOS thresholds, and guidance on special cases and the use of alternative tools. Uninterrupted-flow system elements, such as freeways, have no fixed causes of delay or interruption external to the traffic stream. The freeway chapters are presented first, arranged from the facility level down to the segment level; the chapters for multilane and two‐lane highways Chapter 1/HCM User’s Guide Page 1-3 Structure December 2010
Highway Capacity Manual 2010 follow.Users familiar with the HCM2000 will find that Volume 2 incorporates the Part III uninterrupted-flow chapters,along with the material from the olds hangeRampTCM20,apeaswi rcrsg specinc delault valuesands apter,whi Volume 2 is provided in both three-ring-binder and electronic formats to facilitate interim HCM updates as new research is performed. VOLUME 3:INTERRUPTED FLOW egments Volume 3 contains all of the methodological chapters relating to interrupted- dow system elements.Its c ontent is similar to that of the Volume 2 chapters.The Volume 3 incorporates the interrupted-flow chapters from the HCM2000's Part III,along with the corresponding detailed Part II material.Where applicable n pedestrian and bicycle material has been integrated throughout the Volume3 gn3 chapters,along with public transit material specific to multimodal analyses. Users are referred to the Trasit Capacityd Qulity of Service) (句for transit- ures.The HCM2000 pter has been hap 2010 edi on,which cove mp ter Volume 3 is provided in both three-ring-binder and electronic formats to facilitate interim HCM updates as new research is performed. VOLUME 4:APPLICATIONS GUTDE VOLUME 4:APPLICATIONS GUIDE nenta me(www.HCM2010.org)that include our typesc ontent:supple way and comprehensive case studies.and a technical referencelir 27 The supplemental chapters include the following: ay Merges and Street fadlities ·h wh an Stre Example applications of alternative tools to situations not addressed by the Volume 2 or 3 chapter's methodology; 32. Cont .Additional example problems and calculation results;and .A new chapter on the impact of active traffic management techniques on roadway operations. Manag The methodological interpretations section will develop over time,as users apply the HCM 2010 and pose questions about particular methodologies to the Transportation Research Board(TRB)Committee on Highway Capacity and Quality of Service(AHB40).Clarifications of,interpretations of,and corrections Structure Page 1-4
Highway Capacity Manual 2010 follow. Users familiar with the HCM2000 will find that Volume 2 incorporates the Part III uninterrupted‐flow chapters, along with the material from the corresponding Part II chapters (e.g., specific default values and LOS thresholds) used directly in an analysis. The Interchange Ramp Terminals chapter, which appeared with the uninterrupted‐flow chapters in the HCM2000, appears with the interrupted‐flow chapters (Volume 3) in the HCM 2010. Volume 2 is provided in both three‐ring‐binder and electronic formats to facilitate interim HCM updates as new research is performed. VOLUME 3: INTERRUPTED FLOW VOLUME 3: INTERRUPTED FLOW 16. Urban Street Facilities 17. Urban Street Segments 18. Signalized Intersections 19. TWSC Intersections 20. AWSC Intersections 21. Roundabouts 22. Interchange Ramp Terminals 23. Off-Street Pedestrian and Bicycle Facilities Volume 3 contains all of the methodological chapters relating to interrupted‐ flow system elements. Its content is similar to that of the Volume 2 chapters. The facility chapter is presented first, followed by the segment chapter, the point chapters, and a chapter on off‐street pedestrian and bicycle facilities. Volume 3 incorporates the interrupted‐flow chapters from the HCM2000’s Part III, along with the corresponding detailed Part II material. Where applicable, pedestrian and bicycle material has been integrated throughout the Volume 3 chapters, along with public transit material specific to multimodal analyses. Users are referred to the Transit Capacity and Quality of Service Manual (TCQSM) (5) for transit‐specific analysis procedures. The HCM2000 Unsignalized Intersections chapter has been split into three chapters in the 2010 edition, which individually cover two‐way STOP‐controlled intersections, all‐way STOP‐ controlled intersections, and roundabouts. Finally, the Interchange Ramp Terminals chapter is now included with the interrupted‐flow chapters. Interrupted-flow system elements, such as urban streets, have traffic control devices such as traffic signals and STOP signs that periodically interrupt the traffic stream. Volume 3 is provided in both three‐ring‐binder and electronic formats to facilitate interim HCM updates as new research is performed. VOLUME 4: APPLICATIONS GUIDE VOLUME 4: APPLICATIONS GUIDE Methodological Details Volume 4 is an electronic‐only volume (www.HCM2010.org) that includes four types of content: supplemental chapters, methodological interpretations, comprehensive case studies, and a technical reference library. 24. Concepts: Supplemental 25. Freeway Facilities: Supplemental 26. Freeway and Highway Segments: Supplemental 27. Freeway Weaving: The supplemental chapters include the following: Supplemental • More detailed descriptions of certain computational methodologies, written for users who seek a greater depth of understanding or plan to develop HCM implementation software; 28. Freeway Merges and Diverges: Supplemental 29. Urban Street Facilities: Supplemental 30. Urban Street Segments: Supplemental • Example applications of alternative tools to situations not addressed by the Volume 2 or 3 chapter’s methodology; 31. Signalized Intersections: Supplemental 32. STOP-Controlled Intersections: • Additional example problems and calculation results; and Supplemental • A new chapter on the impact of active traffic management techniques on roadway operations. 33. Roundabouts: Supplemental 34. Interchange Ramp Terminals: Supplemental 35. Active Traffic Management The methodological interpretations section will develop over time, as users apply the HCM 2010 and pose questions about particular methodologies to the Transportation Research Board (TRB) Committee on Highway Capacity and Quality of Service (AHB40). Clarifications of, interpretations of, and corrections Interpretations Case Studies Technical Reference Library Structure Page 1-4 Chapter 1/HCM User’s Guide December 2010
Highway Capacity Manual 2010 to the HCM that have been officially approved by the committee will be posted in the interpretations section of Volume 4 The comprehensive case studies illustrate how to use the HCM to perform b0品 common types of analyses.The case studies are focused on the process of applying the HCM,rather than on the details of performing calculations (which are addressed by the example problems).Case Studies 1 through 5 are derived from the web-based HCM Applications Guidebook (6)that was developed after the HCM2000 was published,while Case Study 6 was developed by the NCHRP 3. 85 project (7). The technical Reference iibrary contains a selection of paners technical reports,and companion documents that provide background information about the development of HCM methodologies. COMPUTATIONAL ENGINES Historically,all HCM methodologies have been fully documented within the om this pattern).How ever,in response to pra titioner needs and i HCM limita methodologies the chaptr ome have reac the point where oes that mputational en ortant m which details of s ome of the mor hed.F he hemple caaulaticn be flly de and the computational engine together provide the most efficient and effective way of fully documenting the methodology. and Quality of Service maintains tational engin s fo act ople proposed changes.These engines are tools for develop g and documenting HCM methodologies and do not have or need the sophisticated interfaces and input data manipulation techniques that would make them suitable for use in an engineering or planning office.The engines are not generally publicly distributed but are made available on request to researchers,practitioners,software COMMERCIAL SOFTWARE To assis sers in of the 1985 vailable that implement hcm tech er interfaces products. ChapterMUser's Guide Page 1-5 Structure
Highway Capacity Manual 2010 to the HCM that have been officially approved by the committee will be posted in the interpretations section of Volume 4. Access Volume 4 at www.HCM2010.org The comprehensive case studies illustrate how to use the HCM to perform common types of analyses. The case studies are focused on the process of applying the HCM, rather than on the details of performing calculations (which are addressed by the example problems). Case Studies 1 through 5 are derived from the web‐based HCM Applications Guidebook (6) that was developed after the HCM2000 was published, while Case Study 6 was developed by the NCHRP 3‐ 85 project (7). The Technical Reference Library contains a selection of papers, technical reports, and companion documents that provide background information about the development of HCM methodologies. COMPUTATIONAL ENGINES Historically, all HCM methodologies have been fully documented within the manual through text, figures, and worksheets (the Freeway Facilities chapter in the HCM2000 represents the first departure from this pattern). However, in response to practitioner needs and identified HCM limitations, methodologies have continued to grow in complexity, and some have reached the point where they can no longer be feasibly documented in such a manner (for example, methodologies that require multiple iterations to reach a solution). In these cases, computational engines become an important means by which details of some of the more complex calculations can be fully described. For the most complex methodologies, the Volume 2 or 3 chapter, the Volume 4 supplemental chapter, and the computational engine together provide the most efficient and effective way of fully documenting the methodology. HCM chapters describe, at a minimum, the process used by a given methodology. For simpler methodologies, the chapters fully describe the computational steps involved. Supplemental chapters in Volume 4 provide calculation details for the more computationally complex methods. Computational engines document all the calculation steps for the most complex methods, such as those involving iterative calculations. The TRB Committee on Highway Capacity and Quality of Service maintains computational engines for most HCM methodologies for the purposes of evaluating methodologies as they are developed, developing new example problems, identifying needed improvements, and judging the impact of proposed changes. These engines are tools for developing and documenting HCM methodologies and do not have or need the sophisticated interfaces and input data manipulation techniques that would make them suitable for use in an engineering or planning office. The engines are not generally publicly distributed but are made available on request to researchers, practitioners, software developers, students, and others who are interested in understanding the inner workings of a particular HCM methodology. COMMERCIAL SOFTWARE To assist users in implementing the methodologies in the manual, commercial software is available (and has been since the publication of the 1985 HCM) to perform the numerical calculations for the more computationally intensive methods. A variety of commercial software products are available that implement HCM techniques and provide sophisticated user interfaces and data manipulation tools. It is the policy of TRB not to review or endorse commercial products. Chapter 1/HCM User’s Guide Page 1-5 Structure December 2010
Highway Capacity Manual 2010 4.INTERNATIONAL USE APPLICATIONS inte rch conduc ted in tof HCM methodolo ies.HCM ver,that the majo ty of the re rchbase.the default values and the typical applications are from North America.particularly from the United States although there is considerable value in the general methods presented,their use outside of North America requires additional emphasis on calibrating the equations and the procedures to local conditions,as well as recognizing major differences in the composition of traffic;in driver,pedestrian, and bicycle characteristics;and in typical geometrics and control measures. METRIC CONVERSION GUIDE The HCM2000(4)was produced as two editions,one using U.S.customary nits and the other using metnc units.Varablesher were suto ard conve figures were rounde Is was re 36 e v ed ,128 or of As described in this chapter's Structure section,there is no metric edition of the HCM2010.Therefore,a soft conversion is favored from U.S.customary units to metric units,so that computational engines produce the same result regardle or the me that h stem used.How ns or the me esults uced b the HCM 2010wit soft co tho se pr uced by e metric version of the HCM2000. Exhibit 1-1 provides approximate conversion factors from U.S.customary to metric units. Page 1-6
Highway Capacity Manual 2010 4. INTERNATIONAL USE APPLICATIONS Capacity and quality‐of‐service analyses have generated interest on an international scale. The HCM has been translated into several languages, and research conducted in numerous countries outside of North America has contributed to the development of HCM methodologies. HCM users are cautioned, however, that the majority of the research base, the default values, and the typical applications are from North America, particularly from the United States. Although there is considerable value in the general methods presented, their use outside of North America requires additional emphasis on calibrating the equations and the procedures to local conditions, as well as recognizing major differences in the composition of traffic; in driver, pedestrian, and bicycle characteristics; and in typical geometrics and control measures. METRIC CONVERSION GUIDE The HCM2000 (4) was produced as two editions, one using U.S. customary units and the other using metric units. Variables in the HCM2000 were subject to hard conversion, meaning that figures were rounded where this was reasonable. For example, a lane width of 12 ft was converted to a rounded value of 3.6 m. In comparison, a soft conversion would multiply 12 ft by a conversion factor of 0.305 m/ft, resulting in a value of 3.66 m. As described in this chapter’s Structure section, there is no metric edition of the HCM 2010. Therefore, a soft conversion is favored from U.S. customary units to metric units, so that computational engines produce the same result regardless of the measurement system used. However, in comparisons of the metric results of methodologies that have not changed from 2000 to 2010, such as multilane highways, small discrepancies may appear: the results produced by the HCM 2010 with soft conversion may be slightly different from those produced by the metric version of the HCM2000. Exhibit 1‐1 provides approximate conversion factors from U.S. customary to metric units. International Use Page 1-6 Chapter 1/HCM User’s Guide December 2010