Traffic Engineering Handbook, 7th Edition

Cẩm nang dành cho Kỹ Sư chuyên ngành - Kỹ thuật giao thông, Phiên bản thứ 7

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List of Illustrations

Chapter 2: Probability and Statistical Analyses Techniques for Traffic EngineeringPerformance Measurement

Figure 3.4 Percent of Fixation Time by Location as a Function of Trials for CarFollowing (One Subject)

Figure 3.5 From Bie Lo, & Wong (2008)

Figure 3.7 Example of Bad Practice in Delineation of Road Path: View 740 ft (225 m)South of Area of Impact

Figure 7.14 Speed–Density Relationship for Edie Hypothesis

Figure 7.11 Greenshields Speed–Density Relationship Plotted Against Actual Speedand Density Data

Figure 8.21 Example of DCM Graphical Output for a Roadway Segment

Chapter 9: Planning, Design, and Operations of Road Segments and Interchanges in UrbanAreas

Figure 9.27 Travel Speed Profiles for Express Lane Build and No-Build AlternativesChapter 10: Design and Control for Interrupted Traffic Flow through Intersections

Figure 12.9 Vehicular Conflict Points

Figure 12.10 Separating Conflict Areas Reduces Driver Workload and the Exposure ofBicycles and Pedestrians to Potential Crashes

Figure 12.11 Illustration of the Effect of Speed Differential between Turning Vehiclesand Through Traffic on Crash Potential

Figure 12.17 Bridgeport Way Multimodal Corridor Access Improvements; BridgeportWay, City of University Place, Washington

Figure 14.3 Flowchart Showing the Steps of a Neighborhood Traffic Calming PlanDevelopment Process, Austin, Texas

Figure 14.4 A Neighborhood Map with Icons Placed by Resident Committee MembersIdentifying Their Initial Draft Plan

Figure 14.5 A Diagram Illustrating Midblock Chokers (Boston Transportation

Department, 2013)

Figure 14.6 Educational Traffic Calming Campaign Flyer from San Antonio, TexasFigure 14.7 Lane Striping Used to Reduce the Travelway Width in Laguna Hills,

California

Figure 14.8 Speed Feedback Sign with Speed-Limit Sign Used Near a School in

Murray, Utah

Figure 14.20 A Raised Crosswalk with a Text-Based Advisory Sign and StampedConcrete in Place of Crosswalk Striping in Salt Lake City, Utah

Figure 15.5 Two-Way Traffic on Half of a Normally Divided Highway Using PositiveBarrier Separation

Figure 15.6 Detour for Closed Road

Figure 15.7 Observed and Predicted Total, Fatal and Injury (FI), and Property DamageOnly (PDO) Crashes vs Traffic Density in Millions of Vehicle Miles of Travel

Figure 16.9 Resilience Precepts and Principles

List of Tables

Chapter 1: Introduction to the Traffic Engineering Handbook and Its Role in EvolvingPractice

Table 12.8 Minimum Design Length of a Left-Turn or Right-Turn Lane, ExcludingQueue Storage

Table 15.3 Observed Capacities for Typical Freeway Work Zones in Vehicles per Hour(VPH)

Table 15.4 Capacity of Long-Term Work Zones in Vehicles per Lane per Hour (VPH)(veh/h/ln)

Way, One-Lane Operation) in Vehicles per Hour (VPH)

Table 15.5 Estimated Capacity of a Shared Right-of-Way Work Zone Strategy (Two-Table 15.6 Index of Change Comparisons with and without Temporary Lane Closuresduring Periods of Work Activity

Table 15.7 Minimum Radii for Work Zone Horizontal Curves Retaining Normal CrownCross-Slopes

Table 16.1 Quick Start Reference Summary to Getting Started in the “Unusual Events”World

Table 16.2 Quick Start Suggested Actions Summary to Getting Started in the “UnusualEvents” World

Table 16.8 Transportation Resources in the Major NIMS Functional CategoriesTable 16.9 Transportation Operational Strategies

Table 16.10 Inclusive Transportation and Outreach for People with Access andFunctional Needs

TRAFFIC ENGINEERING HANDBOOK SEVENTH EDITION

Cover image: Boston Complete Streets Guidelines, Boston Transportation Department; Dunsmuir Separated Bike Lane © Paul Krueger

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Library of Congress Cataloging-in-Publication Data is available:

ISBN 978-1-118-76230-1 (hardback)

978-1-118-76228-8 (epdf)

978-1-118-76226-4 (epub)

Beyond the standard updates to reflect evolving changes in practice, this new edition of the

Handbook also reflects the shifting philosophy of traffic engineering practice in which

transportation professionals no longer serve as merely planners, designers, and operators oftransportation systems Rather, they are integral components of more comprehensive societalroles of community builders, influencers of social and economic change, and investors ofpublic resources

Just as transportation systems must be adapted to meet the changing expectations and needs of

users and increasing costs and threats to the environment, the Traffic Engineering Handbook

cannot be static In this seventh edition, the handbook reflects an effort to reduce traditionalmodal stove-piping and promote a more inclusive approach to the planning, design, and

operation of transportation systems The goal of this shift is to serve the needs of all users anddesign context-sensitive transportation facilities, all with an eye toward developing moreintegrated, sustainable, and resilient transportation solutions to address modern problems andneeds

The expectation is for this edition to equip traffic engineers for the key roles that they will play

in the evolution of communities into hubs of economic and social activity The streets of thetwenty-first century must meet the complex needs of society in a safe, efficient, and cost-

effective manner The organization of this Handbook is reflective of this complexity through a

functionally driven multimodal approach to content categorization In the development of this

Handbook, the editors, along with ITE staff and teams of practicing professionals throughout

North America, have worked to integrate the needs of all modes and all transportation systemusers through a holistic approach rather than just an afterthought We hope that readers willalso recognize, appreciate, and benefit from these changes

Anurag Pande, Ph.D and Brian Wolshon, Ph.D., P.E., PTOE

Editors

Many individuals contributed to this seventh edition of the Traffic Engineering Handbook, including the authors, advisory panel members, reviewers, LeadershipITE (Class of 2014),

and ITE staff Many thanks for all of their efforts

The advisory panel was comprised of a diverse group of transportation professionals withrecognized expertise and active involvement in traffic engineering issues and practices Thepanel members, listed below, worked with ITE staff and the handbook's co-editors, in thedevelopment of the scope of work and in defining a new approach for this handbook Theseindividuals served as mentors to each of the chapter authors as they developed the technicalcontent for their chapters They also participated in a series of critical reviews providing keyfeedback at various stages in the development process

Eagan Foster

Eli Veith

Emmanuel AnastasiadisFred Hanscom

Richard (Rich) CoakleyRichard Nassi

Beverly Kuhn

John LaPlante

ITE staff also provided valuable input to development process Thomas W Brahms providedoverall guidance and vision for the handbook Lisa Fontana Tierney managed the development

Anurag Pande, Ph.D

Brian Wolshon, Ph.D., P.E., PTOE

Co-editors

Handbook) The Handbook's prior editions have been widely used by public agencies,

consultants, and educational institutions as a basic day-to-day reference source on the proventechniques of the practice The primary audience for this publication is practicing

professionals responsible for the safe and efficient operation of the roadway transportationnetworks The secondary audience includes academia in general and educators in particular

However, increasing congestion, even as the highway network continued to grow in subsequentdecades, led to the realization that adding capacity, while useful for a period of time, was notthe only solution to the congestion problem As a result, the management of traffic demand alsobecame part of the traffic engineering profession as a way to address congestion The concept

to create a safer environment for all users, encourage economic activity in downtown areas,and contribute to revitalized city centers that facilitate urban economic growth

centric approaches to traffic engineering In this edition, traffic engineering principles arepresented as tools to meet broader societal needs to facilitate the safe and efficient movement

Among the most significant of these changes is the move away from traditional automobile-of all road users The authors have sought to incorporate in this publication the needs of the fullrange of users (pedestrians, bicyclists, automobile/public-transit users of all ages and abilities,and emergency- and commercial-vehicle operators) that rely on the surface transportationsystem, while keeping it true to its roots as the “go-to” resource on the fundamental principlesand applications of traffic planning, operations, control, design, and analysis This shift is inrecognition of the fact that traditional, narrowly focused solutions have, at times, been

inadequate to address the needs of all users

This edition of the Handbook also integrates contemporary approaches to traffic engineering

and planning to include context-sensitive solutions, resiliency, environmental sensitivity,

system reliability, and sustainability By emphasizing the application of performance-baseddesign and analysis philosophies and promoting a comprehensive design approach, it tries toeliminate the long-standing sequestrations that exist in the specialized fields within trafficengineering Performance-based design seeks to design, analyze, and build transportation

systems that are economical and adaptable to the changing demands, user preferences, andconditions placed upon them Under this approach, planners and engineers attempt to quantifyperformance before, during, and after construction so that decisions can be made based on anumber of quantifiable cost-and-benefit performance measures instead of solely on the cost ofconstruction Similarly, benefits have, in the past, been measured narrowly in terms of level ofservice and reduced crash frequency/rate, when in reality there are many other measures thatcan be applied It has been suggested that, in addition to their roles as quantitative analysts oftraffic performance, traffic engineers of the future can use these approaches to serve as

“financial advisors” for strategic investment of public funds for the improvement of mobilityand creation of more sustainable, resilient, and livable communities

III Organization of the Handbook

To reflect evolving views of traffic engineering and the variety of approaches, ITE has

this publication This edition of the Handbook is divided into four functional content areas that group chapters by related topics based on traffic engineering roles and tasks Functional

content areas deliver traditional technical material, a mainstay of prior editions, within

inclusive, integrated, and overlapping topical areas These areas are aimed at encouraging aconcurrent, multimodal, and multiuse approach to planning, design, operation, and management

The goal of this format is to better connect the roadway with the surrounding land-use

environment, considering all user categories and other relevant elements This is a departurefrom the traditional layered approach, which typically considers vehicular traffic first and thenconsiders user groups such as pedestrians and persons with disabilities The intent is thatproviding a harmonization of the material will build an awareness of and appreciation for theintegration and interaction of one specific topic with another

Design and Operation of Uninterrupted Flow Facilities (freeways, multilane highways, and two-lane rural roadways)—covering the fundamentals of uninterrupted traffic flow,

along with design and operations of uninterrupted flow facilities in urban and rural areas

incorporating the multimodal LOS concepts for the design and operation of complete

streets This functional area also incorporates issues related to the management of access,traffic calming, and parking on urban and suburban streets

Special Operational Considerations—this topical area includes coverage of issues

related to planning, design, control, management, and operations for planned special

events, transportation-incident conditions, and emergencies Areas of discussion includemanaged lanes, work zones, planned-event traffic management, evacuations, and disasterrecovery

Under this format, there are no exclusive chapters that address concepts such as ITS

(intelligent-transportation systems), safety, traffic signals, and communication strategies Tofurther aid the reader in locating relevant content, we note chapters that cover some of theseimportant topical areas here:

ITS: Adaptive components of transportation systems are part and parcel of the moderntraffic engineer's arsenal ITE, in collaboration with the U.S Department of Transportation(USDOT) Research and Innovative Technology Administration (RITA) Intelligent

Transportation Systems (ITS) Joint Program Office (JPO) and ITS America, produced the

ITS ePrimer (www.pcb.its.dot.gov/ePrimer.aspx), which describes these systems in great

depth in the form of up-to-date web-based modules (Knowledge Exchange: ePrimer) In the Handbook, the ITS components are discussed in Chapter 8, Chapter 9, Chapter 10,

Chapter 13, and Chapter 15 in the context of problems they are designed to solve These

provide appropriate background and context to support application of the ePrimer.

Safety: The concept of safety in the HSM is described as nominal and substantive safety.

Nominal safety is achieved by making sure that all the components of design and trafficcontrol meet the criteria prescribed in the governing manuals The idea of nominal safety interms of the human factors associated with these standards is described in Chapter 3 Thisfoundation is then reinforced within the context of design functions in later chapters of this

book Substantive safety is described by the measure of safety expressed in the form of

safety measurement are first presented in Chapter 2 Chapter 4 describes the relevant

expected number of crashes on a facility The statistical concepts related to substantive-procedures in detail, which are then applied in the context of rural uninterrupted flow inChapter 8 Specific safety issues are also discussed in the context of urban uninterruptedflow (Chapter 9), urban streets/intersections (Chapter 10), and access management

(Chapter 12)

Traffic signals: In the previous edition of the Handbook, the subject of traffic signals was

covered in a single chapter Signals are traffic control devices, and their application iscontext-sensitive In this edition, the signals to implement ramp metering are covered inChapter 9, because their application concerns urban uninterrupted flow In contrast, thebasics of signal control are discussed in Chapter 10 as part of the basics of interruptedflow within a multimodal environment Finally, Chapter 11 adds to the discussion by

highlighting traffic-signal applications within the context of complete streets

To guide readers familiar with previous editions of the Handbook through the content

reorganization, Table 1.1 maps the content of the previous edition to the functional contentareas and chapters of this edition Content from some of the chapters from the sixth edition(e.g., Chapter 4, “Traffic and Flow Characteristics”) still map to individual chapters in thecurrent edition, whereas content from several individual chapters from the sixth edition (e.g.,Chapter 5, “Safety” and Chapter 12, “Traffic Control Signals”) is now distributed over

Chapter 3: Road UsersChapter 7: Traffic FlowCharacteristics for Uninterrupted-FlowFacilities

Chapter 8: Design and Operations ofRoad Segments and Interchanges inRural Areas

Chapter 4: Traffic and

Flow Characteristics

Uninterrupted-FlowFacilities

Design and Operation ofComplete Streets in TownCenters and Neighborhoods

Chapter 7: Traffic FlowCharacteristics for Uninterrupted-FlowFacilities

Chapter 10: Design and Control forInterrupted Traffic Flow throughIntersections

Chapter 5: Safety* Background and

FundamentalsUninterrupted-FlowFacilities

Design and Operation ofComplete Streets in TownCenters and Neighborhoods

Chapter 2: Probability and StatisticalAnalyses Techniques for TrafficEngineering Performance MeasurementChapter 4: Traffic Engineering StudiesChapter 8: Design and Operations ofRoad Segments and Interchanges inRural Areas

Chapter 9: Planning, Design, andOperations of Road Segments and

Chapter 11: Design and Operation ofComplete Streets and IntersectionsChapter 12: Access ManagementChapter 14: Traffic CalmingChapter 6: Probability

and Statistics

Background andFundamentals

Chapter 2: Probability and StatisticalAnalyses Techniques for TrafficEngineering Performance MeasurementChapter 7: Geometric

Design for Traffic*

Uninterrupted-FlowFacilities

Design and Operation ofComplete Streets in TownCenters and Neighborhoods

Chapter 8: Design and Operations ofRoad Segments and Interchanges inRural Areas

Chapter 9: Planning, Design, andOperations of Road Segments andInterchanges in Urban AreasChapter 10: Design and Control forInterrupted Traffic Flow throughIntersections

Chapter 11: Design and Operation ofComplete Streets and IntersectionsChapter 8: Traffic

Engineering Studies

Background andFundamentals

Chapter 4: Traffic Engineering Studies

Chapter 9: Planning for

Operations

Background andFundamentals

Chapter 6: Forecasting Travel Demand

Chapter 11: Signs and

Pavement Markings*

Uninterrupted-FlowFacilities

Design and Operation ofComplete Streets in TownCenters and NeighborhoodsSpecial Operational

Considerations

Chapter 8: Design and Operations ofRoad Segments and Interchanges inRural Areas

Chapter 9: Planning, Design, andOperations of Road Segments andInterchanges in Urban AreasChapter 10: Design and Control forInterrupted Traffic Flow throughIntersections

Chapter 11: Design and Operations of

Chapter 14: Traffic CalmingChapter 15: Work Zone Maintenance ofTraffic and Construction Staging

Chapter 12: Traffic

Control Signals*

Uninterrupted-FlowFacilities

Design and Operation ofComplete Streets in TownCenters and Neighborhoods

Chapter 9: Planning, Design, andOperations of Road Segments andInterchanges in Urban AreasChapter 10: Design and Control forInterrupted Traffic Flow throughIntersections

Chapter 11: Design and Operation ofComplete Streets and IntersectionsChapter 13: Access

Management

Design and Operation ofComplete Streets in TownCenters and Neighborhoods

Chapter 12: Access Management

Chapter 14: Parking Design and Operation of

Complete Streets in TownCenters and Neighborhoods

Chapter 13: Parking

Chapter 15: Traffic

Calming

Design and Operation ofComplete Streets in TownCenters and Neighborhoods

Considerations

Chapter 6: Forecasting Travel DemandChapter 11: Design and Operation ofComplete Streets and IntersectionsChapter 14: Traffic Calming

Chapter 15: Work Zone Maintenance ofTraffic and Construction Staging

Chapter 16: Traffic Management forPlanned, Unplanned, and EmergencyEvents

Chapter 17: Traffic

Regulation and Control*

Uninterrupted-FlowFacilities

Design and Operation ofComplete Streets in TownCenters and NeighborhoodsSpecial Operational

Considerations

Chapter 8: Design and Operations ofRoad Segments and Interchanges inRural Areas

Chapter 9: Planning, Design, andOperations of Road Segments andInterchanges in Urban AreasChapter 10: Design and Control forInterrupted Traffic Flow throughIntersections

Chapter 11: Design and Operation of

: ParkingChapter 14: Traffic CalmingChapter 15: Work Zone Maintenance ofTraffic and Construction Staging

Chapter 15: Work Zone Maintenance ofTraffic and Construction Staging

* Content from the chapter in the previous edition is now distributed over multiple chapters to ensure that the relevant concepts

are presented within the right context.

Beyond mapping the content of the sixth edition, we have also covered several new areas ofemerging interest to traffic engineers: namely, traffic management during planned and

unplanned emergency events and, of course, multimodal LOS Conversely, it should also benoted that not all content from the sixth edition has made it into the seventh edition For

example, in addressing the concepts of interrupted flow, the readers are now referred to the

Traffic Control Devices Handbook (Seyfried, 2013) for a discussion of traffic control

equipment standards and maintenance Perhaps most important to note is that the breadth of thetopics within the field is so vast that it is not realistically possible to capture the full breadth ofall topics within a single book Nevertheless, within that reality, the level of coverage hereprovides valuable background and foundational information to support judgments and decisionmaking, as well as to guide readers to resources and publications that contain more specificdetails on topics of interest

generally applicable to any location, road type, and user group, as well as the students andresearchers of the academic community who are seeking to learn about and build upon thefoundational concepts of the traffic engineering profession While this approach may presentsome initial challenges for educators who use this publication in the classroom, it is expectedthat the academic community will use this challenge as an opportunity to take a holistic

approach to traffic engineering in educating their students to become holistic traffic engineering

Probability and Statistical Analyses Techniques for

Traffic Engineering Performance Measurement

John McFadden Ph.D., P.E., PTOE, Seri Park Ph.D., PTP and David A Petrucci Jr P.E.,PTOE

I Introduction

Traffic-performance measurement and the development of traffic-performance-based toolsoften require the collection and analysis of data The role of a traffic engineer includes theapplication of technical traffic engineering principles in combination with risk-managementstrategies and the economic analysis of alternatives to make better-informed decisions Thischapter describes some of the fundamental statistical techniques associated with completingthese tasks The application of appropriate statistical techniques to conduct traffic engineeringstudies also helps engineers make more informed decisions Engineers who collect and analyzedata with appropriate statistical procedures are better equipped to avoid inaccurate

procedures used to conduct the relevant studies are detailed in Chapter 4 of this handbook, thischapter explores some of the statistical techniques used for collecting, analyzing, and

interpreting the data gathered for evaluation of technical aspects of traffic engineering

term evaluation of engineering projects also includes analysis using engineering-economicsprinciples Therefore, in addition to the statistical measures and techniques, this chapter alsodiscusses the concepts of engineering economics

a sample is a subset from a population When the population is very large, it is often not

feasible or cost-effective to collect data from the entire population, so a representative samplefrom the population is used to make inferences about the entire population If data from theentire population can be obtained, measurements computed using all data values in a

population are called parameters; measurements computed using the samples are called

statistics Statistics from large samples drawn from a population yield more precise estimates

of population parameters than those computed from a smaller sample

It is important to be aware that statistics computed on data obtained from a poorly designedsampling strategy or experiment are at greater risk of biased performance evaluations Tominimize this risk, the sampling strategy used to meet the needs of a particular study must becarefully designed Several of these strategies are described in the following section

3 Systematic sample: A sample that numbers all members of the population sequentially, and

starting from a point at random, includes every k th member of the population in the sample

4 Cluster sample: A sample that divides the population into preexisting segments or clustersand then randomly selects cluster(s) from which data will be collected on all individualswithin the cluster(s)

2 Non-sampling error—This is the result of poor sample design, sloppy data collection,faulty measuring instruments, bias in questionnaires, or data entry errors