Aligning Geometric Design with Roadway Context (2022) / Chapter Skim
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7 Chapter 2: Research Tasks and Findings Chapter 2 provides a summary of research activities and findings from the following tasks: o Task 1: Agency Surveys o Task 2: Literature Review o Task 3: Synthesize Approaches o Task 4: Engagement with the AASHTO TCGD o Task 5: Draft Annotated Outline o Task 6: Draft Part IV Chapters o Task 7: Workshops TASK 1: AGENCY SURVEYS The research team surveyed state transportation agencies, members of NACTO, and other agencies (such as Oregon Metro) to locate innovative design approaches, manuals, and standards.
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8 Survey Approach The research team prepared the following six discussion topics and sent them to the agencies in advance of the meetings to allow the representatives to gather internal feedback from other staff: 1. Information about the processes and considerations in developing their products and opportunities 2.
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9 Florida Department of Transportation The Florida Department of Transportation (FDOT) used NCHRP Report 855: An Expanded Functional Classification System for Highways and Streets (1)
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10 departments and disciplines to establish design guidance that meets the needs of their communities and projects. Massachusetts Department of Transportation Massachusetts Department of Transportation's (MassDOT)
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11 New Jersey Department of Transportation New Jersey Department of Transportation (NJDOT) relies primarily on the NJDOT Roadway Design Manual (7)
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12 Many of PennDOT's projects are based on the long-range plan for their local municipality. PennDOT provides the transportation network to serve that plan and changes the geometric design and speed to meet the needs of the users of a project.
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13 Texas Department of Transportation Texas Department of Transportation (TxDOT) uses their Roadway Design Manual (10)
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14 WSDOT suggested national guidance provide flexibility in using classification. This would allow states to consider direct application of context in decisions or adapt them depending on project planning and programming processes, data availability, and other considerations.
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15 cross-slope design guidance, because they are focused on urban streets, and it is not often feasible to meet the cross-slope state's design standards. In some cases, the design guidance for urban areas is for larger blocks and they are often dealing with smaller city blocks with multiple driveways.
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16 o TxDOT, KDOT, NJDOT, SDDOT, TDOT, City of Oakland, and City of Cambridge have no documented design guidance related to context and still find ways to execute design flexibility and context-based design decisions. o States with Centralized Offices are often more easily able to implement these strategies.
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17 References 1. Stamatiadis, Nikiforos, Adam Kirk, Don Hartman, Jeff Jasper, Samantha Wright, Michael King, and Rick Chellman.
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18 TASK 2: LITERATURE REVIEW The research team conducted a literature review for potential Green Book 8 Part IV content to understand considerations for the range of potential user vehicles (i.e., micro-mobility [scooters] to large trucks [oversize/overweight]
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19 each document is provided in the following subsections. Some of the documents selected are state manuals that describe how they are defining and integrating context classification into design.
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20 A Guide for Functional Highway Classification (1964) To summarize information for A Guide for Functional Highway Classification (3)
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21 • An open source transect-based planning and regulatory tool supported by the Center for Applied transect Studies. • A tool to guide the form of the built environment to create and protect development patterns that are compact, walkable, and mixed-use.
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22 o Village/Town Center o Low Density • Urban o Park o Residential o Central Business District The area types, combined with roadway types, are used to inform such things as design speed, lane widths, median width and function, and shoulder width. An example is provided in Exhibit 2-6.
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23 Exhibit 2-7. Land Use Contexts Exhibit 2-8.
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24 Seven types of thoroughfares are introduced. ITE describes their impact on design, including desired operating speed and pedestrian facilities, their compatibility with different context zones, and their relationship to functional classification, shown in Exhibit 2-9.
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25 Highway Functional Classification: Concepts, Criteria, and Procedures (2013) This guidance document builds upon and updates the two most recent guidance documents circulated by FHWA, namely: • Highway Functional Classification: Concepts, Criteria and Procedures, March 1989 • Updated Guidance for the Functional Classification of Highways Memorandum, October 14, 2008 It describes procedures and processes for assigning functional classifications to roadways and adjusting urban area boundaries.
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26 Exhibit 2-10. Philadelphia Street Types NCHRP Report 785: Performance-Based Analysis of Geometric Design of Highways and Streets NCHRP Report 785 (13)
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27 Exhibit 2-11. NCHRP Report 785 Performance-Based Analysis Application Framework FDOT District 7 Freight Roadway Design Considerations (2015)
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28 Exhibit 2-12. FDOT District 7 Freight Activity and Land Use Compatibility ADOT Complete Transportation Guidebook (2016)
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29 Exhibit 2-13. ADOT Design Elements Priority CalTrans Design Manual Chapter 80 Application of Design Standards (2016)
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30 NCHRP Report 855: An Expanded Functional Classification System for Highways and Streets (2018) NCHRP Report 855 (17)
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31 Exhibit 2-14. NCHRP Report 855 Contexts WSDOT Chapter 1102: Context Determination (2018)
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32 Exhibit 2-15. WSDOT Context Factors Exhibit 2-16.
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33 • Industrial Warehouse • Suburban Commercial • Suburban Residential • Urban Commercial • Urban Residential • Urban Core The contexts are determined based on the kinds, mix, scale, and intensity of uses and activities. This includes density of buildings and structures, setback, public street and driveway connections, and multimodal transportation networks.
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34 Exhibit 2-18. FDOT Allowable Design Speed Ranges ODOT Blueprint for Urban Design (2020)
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35 Exhibit 2-19. ODOT General Modal Consideration in Different Urban Contexts Key Findings Based on the summaries of the priority documents, the research team identified key findings that could influence content for the Green Book Part IV Chapters.
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36 Exhibit 2-20. Land Use Context: State Adaptations (developed by NCHRP Project 15-77)
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37 Exhibit 2-21. Context-Based Dimensional Values Other Observations Additional key findings from the literature review include: • Functional class remains an important network planning concept in current planning and design practice.
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38 2. Oregon Department of Transportation (ODOT)
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39 18. Washington Department of Transportation (WSDOT)
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40 TASK 3: SYNTHESIZE APPROACHES The research team synthesized approaches for organizing the Green Book 8 Draft Part IV Chapters (Chapters 13 through 19) , which were informed by the survey results of Task 1 and first stage of the Task 2 literature review.
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41 Exhibit 2-22. Context Classification Driven Approach Functional Classification Driven Some state agencies, including WSDOT, have fewer context classifications, or land use contexts, and rely heavily on functional classification.
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42 Exhibit 2-23. Functional Classification Driven Approach Functional/Context Classification Combination MassDOT provides an example of an approach that uses an extensive set of functional classification/roadway types and context classifications/area types, with eight land use contexts and six roadway types.
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43 Legacy Facility Types Several states, including SDDOT and NJDOT, represent a legacy AASHTO approach (Green Book 1-6) that relies on legacy land use contexts and facility types.
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44 rely on the direct classification extensively. Some new users are adapting internally to understand how to apply concepts within their jurisdictions.
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45 Exhibit 2-25. Overview of Parts I, II, and III Part I: Introduction Chapters • CHAPTER 1: OVERVIEW • CHAPTER 2: PERFORMANCE-BASED EVALUATION CONCEPTS • CHAPTER 3: DESIGN DECISION-MAKING Key Concepts: • Guides users to concepts and principles that support flexible, multimodal design • Establishes that meeting intended project outcomes is more critical than attaining specific design criteria • Introduce performance-based evaluation concepts that help users understand project contexts • Overview of considerations of design decision-making will provide users with the means to becoming objectively informed about risk management approaches Part II: Performance-based Evaluations • CHAPTER 4: PERFORMANCE METRICS • CHAPTER 5: DESIGN MODEL • CHAPTER 6: APPLYING A PERFORMANCE-BASED PROCESS FRAMEWORK Key Concepts • Defines a design model and performance-based process framework • Describes how the components within the design model establish project elements associated with the context • Establishes a project context considering modules o Land use and roadway functional class o Project type (new construction, reconstruction, projects on existing alignment)
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46 Having users understand the basic elements of Parts I, II, and III allows Part IV content to focus on the specific considerations of integrating context classification into roadway planning and design and content needed to support context classification. This may include priority for topics beyond modal accommodation, including natural environment, safety, social justice, and historic preservation/culture.
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47 Exhibit 2-26. Overview of Part IV Table of Contents Part IV: FACILITY DESIGN IN CONTEXT • CHAPTER 13: CONTEXT AND FACILITY TYPE CONSIDERATIONS 13.1: INTRODUCTION 13.2: CONTEXT CLASSIFICATION 13.3: FACILITY TYPES 13.4: PROJECT CONSIDERATIONS 13.5: FACTORS BEYOND CONTEXT CLASSIFICATION 13.6: USERS 13.7: CROSS SECTION AND SPATIAL ALLOCATION 13.8: SPEED CONSIDERATIONS 13.9: APPROPRIATE DESIGN CONTROLS 13.10: EXPECTED PERFORMANCE 13.11: FINANCIAL FEASIBILITY 13.12: CONSIDERING DESIGN VALUE RANGES • CHAPTER 14-19: SPECIFIC CONTEXT CLASSIFICATION XX.1: UNDERSTANDING CONTEXT XX.2: PROJECT CONSIDERATIONS XX.3: NETWORK CONSIDERATIONS XX.4: SEGMENT DESIGN CONSIDERATIONS XX.5: INTERSECTION DESIGN CONSIDERATIONS XX.6: ACCESS CONSIDERATIONS XX.7: CROSSING CONSIDERATIONS The research team shared the Draft TOC with the NCHRP 15-77 Project Panel and solicited initial input.
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48 TASK 4: AASHTO TCGD ENGAGEMENT This chapter summarizes the engagement activities between the research team, the NCHRP Project 15-77 Panel, and the AASHTO TCGD. The research approach includes a meeting with the AASHTO TCGD at different milestones throughout the project to share project findings and collect input.
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49 may evolve as part of GB8 development. The research team emphasized value in continued coordination with NCHRP 15-72 research team, who also participated in the discussion to give updates on their project.
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50 TASK 5: INTERIM REPORT - PROPOSED ANNOTATED OUTLINE FOR PART IV CHAPTERS Task 5: Interim Report documented the initial tasks (Tasks 1-4 and Task 7) of NCHRP Project 15-77.
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51 TASK 6: DRAFT PART IV CHAPTERS Task 6 involved developing Draft Part IV Chapters, including: • Chapter 13: Context and Facility Type Considerations • Chapter 14: Rural and Natural Areas • Chapter 15: Rural Towns • Chapter 16: Suburban • Chapter 17: Urban • Chapter 18: Urban Core • Chapter 19: Industrial, Warehouse, or Port The research team submitted draft chapters for NCHRP Project 15-77 Panel review and facilitated panel meetings to discuss specific chapter comments and content for each chapter. Panel input was incorporated into the Revised Draft Chapters developed as part of Task 9: Final Deliverable and submitted as a separate deliverable from the final report.
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52 • Content for future inclusion in GB8 Parts: While developing content for the Part IV Chapters, the research team created content that was later determined to be better suited in other GB8 Parts. This information is noted in the Draft Part IV Chapters and "Potential Future GB8 Material" is included at the end of Draft Chapter 13.
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53 may need to be completed by the NCHRP Project 07-29 research team. In addition, other relevant research projects (e.g., NCHRP Project 15-76: Designing for Target Speed)
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54 TASK 7: WORKSHOP As part of Task 7, the research team prepared for and facilitated a workshop with National Association of City Transportation Officials (NACTO) , Institute of Transportation Engineers (ITE)
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55 • Overview of Initial Project Findings • Overview of Draft Table of Contents for Draft Part IV Chapters of the Green Book 8 • Guidance needs related to Suburban Arterials • Guidance needs related to Urban Core Roadways • Design influence factors beyond context and functional classification o Modal integration o Natural environment o Community characteristics o Social demographics • Functional forms and configurations that optimize user quality of service • Application to real-world project examples In addition to these topics, the workshop was structured to allow time for representatives to comment broadly on considerations for the Green Book 8. Input and feedback received during the workshop inform the development of the Draft Part IV Chapters in Task 6.
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56 provide opportunities to develop innovative drainage designs and treat water within the right-of-way. • Quality of service: A key question to consider is "when we describe quality of service, which roadway users are we referring to?
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