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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2018. Developing an Expanded Functional Classification System for More Flexibility in Geometric Design. Washington, DC: The National Academies Press. doi: 10.17226/25178.
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NCHRP Web-Only Document 230: Developing an Expanded Functional Classification System for More Flexibility in Geometric Design Nikiforos Stamatiadis Department of Civil Engineering University of Kentucky Lexington, KY Michael King Nelson\Nygaard New York, NY Rick Chellman TND Engineering Portsmouth, NH Adam Kirk Don Hartman Jeff Jasper Samantha Wright Kentucky Transportation Center University of Kentucky Lexington, KY Contractor’s Final Report for NCHRP Project 15-52 Submitted January 2018 ACKNOWLEDGMENT This work was sponsored by the American Association of State Highway and Transportation Officials (AASHTO), in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program (NCHRP), which is administered by the Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied committees, task forces, and panels annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

iv ACKNOWLEDGMENTS The research reported herein was performed under NCHRP 15-52 by the Kentucky Transportation Center at the University of Kentucky and Nelson/Nygaard. The University of Kentucky is the contractor for this study, and Dr. Nikiforos Stamatiadis, Professor of Civil Engineering, is the principal investigator. The other contributing authors of this report are Adam Kirk, Don Hartman, Jeff Jasper, Samantha Wright, Michael King, and Rick Chellman. The members of the Working Advisory Group have also provided continued input and assisted the team in refining the proposed classification scheme. The team expresses its gratitude to Mr. Scott Bradley, MNDOT; Mr. Pasco Bakotich, WSDOT; Mr. Robert Koehler, OKI MPO; and Mr. John Moore, KYTC; for their reviews and guidance. The authors would also like to acknowledge all members who participated in the survey. We would also like to thank the members of the Subcommittee on Geometric Design and its Chair, Mr. Jeff Jones, for their input in this process. Finally, the contribution and guidance of the NCHRP Panel should be mentioned. Without their hard work and diligence in providing comments, this work would not have been successfully completed.

v TABLE OF CONTENTS SUMMARY .................................................................................................................................... x CHAPTER 1 INTRODUCTION AND RESEARCH APPROACH ................................................... 1 Problem Statement ................................................................................................................ 1 Research Objectives and Approach ....................................................................................... 2 Organization of the Report ..................................................................................................... 3 CHAPTER 2 LITERATURE SYNTHESIS ..................................................................................... 5 Functional Classification System ........................................................................................... 5 Functional Classification for State Agencies ........................................................................ 11 Functional Classification System Issues .............................................................................. 14 Flexibility in Highway Design ................................................................................................ 22 Summary .............................................................................................................................. 27 CHAPTER 3 EXISTING CLASSIFICATION USES ..................................................................... 29 Participant Information ......................................................................................................... 29 Classification System Impacts ............................................................................................. 29 Alternative Functional Classification .................................................................................... 36 CHAPTER 4 ALTERNATIVE CLASSIFICATION SYSTEMS ...................................................... 37 Existing Alternative Classification Systems .......................................................................... 37 Additional Alternative Systems ........................................................................................... 109 UKY/NN System-Independent Multimodal Classification Alternative ................................. 114 Evaluation of Alternative Classification Systems ............................................................... 115 Evaluation Summary .......................................................................................................... 120 CHAPTER 5 PROPOSED FUNCTIONAL CLASSIFICATION SYSTEM .................................. 125 Alternative Classification System Development ................................................................. 125 Expanded FCS Components ............................................................................................. 127 Expanded FCS Modal Accommodations ........................................................................... 140 Expanded FCS Matrix ........................................................................................................ 154 Expanded FCS Application ................................................................................................ 155 CHAPTER 6 EXPANDED FCS IMPLEMENTATION ................................................................ 167 Expanded FCS Implementation Impacts ............................................................................ 167 Implementation Plan .......................................................................................................... 170 FCS and Expanded FCS relationship ................................................................................ 172 Pilot Implementation ........................................................................................................... 173

vi CHAPTER 7 CONCLUSIONS AND FUTURE RESEARCH ...................................................... 177 Conclusions ........................................................................................................................ 177 Future Research ................................................................................................................ 182 References ................................................................................................................................ 183 APPENDIX A APPENDIX B LIST OF TABLES Table 1 U.S. Census Bureau urban area types defined by population range ............................... 8 Table 2 FHWA urban area types defined by population range ..................................................... 9 Table 3 Summary of scores for FCS assessment ....................................................................... 34 Table 4 AustRoads functional classification of rural roads .......................................................... 45 Table 5 AustRoads functional classification of urban roads ........................................................ 45 Table 6 Normal and EDD ............................................................................................................ 47 Table 7 Connection between land use context and street type ................................................... 52 Table 8 Charlotte Guide and FCS relationship ............................................................................ 54 Table 9 Roadway design expectations and design elements by user group .............................. 55 Table 10 Land use contexts for creek overlay ............................................................................. 57 Table 11 Street types and design elements for roadway segments ............................................ 58 Table 12 Complete Streets Chicago context definition ............................................................... 63 Table 13 Complete Streets Chicago road function types ............................................................ 64 Table 14 Complete Streets Chicago and FCS relationship ......................................................... 65 Table 15 Complete Streets Chicago modal hierarchies .............................................................. 65 Table 16 Complete Streets Chicago assemblage table for Thoroughfare .................................. 67 Table 17 Complete Streets Chicago overlays ............................................................................. 69 Table 18 Context Zone description ............................................................................................. 72 Table 19 Thoroughfare type description ...................................................................................... 74 Table 20 Thoroughfare and FCS relationships ........................................................................... 75 Table 21 Design elements by thoroughfare type ......................................................................... 76 Table 22 MassHighway area types and community contexts ..................................................... 79 Table 23 MassHighway and FCS relationship ............................................................................ 82 Table 24 Additional modal considerations and likely volumes / activity ...................................... 83 Table 25 Context definition criteria and values ........................................................................... 86 Table 26 Roadway categories ..................................................................................................... 87

vii Table 27 Typical dimension for cross section elements .............................................................. 89 Table 28 NACTO Guide design speed implications .................................................................... 97 Table 29 Oregon DOT and FCS relationship .............................................................................. 99 Table 30 Roadway categories ................................................................................................... 104 Table 31 Design matrix example ............................................................................................... 106 Table 32 Cross section elements .............................................................................................. 108 Table 33 Abu Dhabi street families, transport capacity, and land use context .......................... 110 Table 34 Scoring of alternative classification systems .............................................................. 118 Table 35 Summary of alternative classification systems ........................................................... 121 Table 36 Expanded FCS context categories ............................................................................. 129 Table 37 Safety evaluation summary ........................................................................................ 166 Table 38 NCHRP 15-52 research implementation plan ............................................................ 171 Table 39 Implementation steps and timetable ........................................................................... 172 Table 40 Existing and Expanded FCS relationship ................................................................... 173

viii LIST OF FIGURES Figure 1 Mobility and access proportion of service by functional class (FHWA, 1982) ................. 6 Figure 2 Example of Tennessee DOT guidance ......................................................................... 13 Figure 3 Access and mobility proportioning (FHWA, 2013) ........................................................ 18 Figure 4 US 460 at Salyersville, KY ............................................................................................ 20 Figure 5 Hub and spoke road network ........................................................................................ 20 Figure 6 Grid road network .......................................................................................................... 21 Figure 7 State DOTs responding to survey ................................................................................. 30 Figure 8 Effects of classification on Programming ...................................................................... 31 Figure 9 Effects of classification on Planning .............................................................................. 32 Figure 10 Effects of classification on Design ............................................................................... 32 Figure 11 Effects of classification on Construction ...................................................................... 33 Figure 12 Effects of classification on Maintenance and Operations ............................................ 33 Figure 13 Link and place axes of arterial streets ......................................................................... 40 Figure 14 ARTISTS street classification table ............................................................................. 40 Figure 15 Overview of ARTISTS approach fit into a complete decision and design process ..... 42 Figure 16 Context categories for AustRoads road classification ................................................. 44 Figure 17 Design Domain concept, AustRoads Road Design Guide (2006) ............................... 48 Figure 18 Design Domain example for shoulder width, AustRoads Road Design Guide (2006) 48 Figure 19 Six-step process .......................................................................................................... 50 Figure 20 Activity centers, corridors, and wedges growth framework ......................................... 51 Figure 21 Modal orientation of street types ................................................................................. 57 Figure 22 Main street typical cross section ................................................................................. 60 Figure 23 Avenue typical cross section ....................................................................................... 61 Figure 24 Boulevard typical cross section ................................................................................... 61 Figure 25 Complete Streets Chicago design tree for pedestrian mode priority and Downtown .. 66 Figure 26 Development continuity ............................................................................................... 71 Figure 27 Thoroughfare design stages ....................................................................................... 77 Figure 28 Area types and built form illustrations ......................................................................... 80 Figure 29 Matrix of context and road types ................................................................................. 88 Figure 30 Example of alternative cross section choices ............................................................. 90 Figure 31 Example of relative modal importance ........................................................................ 91 Figure 32 NACTO Downtown and Neighborhood street types .................................................... 94 Figure 33 NACTO Residential street types ................................................................................. 95

ix Figure 34 NACTO Guide corner radius ....................................................................................... 96 Figure 35 Intersection of Contexts along OHP Designated Urban Highways within the Urban Growth Boundary (UGB) ............................................................................................................. 98 Figure 36 Urban business area design elements ...................................................................... 100 Figure 37 Context definition criteria and values ........................................................................ 103 Figure 38 Matrix of context and road types ............................................................................... 105 Figure 39 Selection of composite functional classification ........................................................ 114 Figure 40 Expanded FCS framework ........................................................................................ 126 Figure 41 Expanded FCS context categories ............................................................................ 128 Figure 42 Expanded FCS framework user matrix ..................................................................... 135 Figure 43 Networks overlay ....................................................................................................... 138 Figure 44 Expanded FCS driver interaction matrix ................................................................... 143 Figure 45 Expanded FCS bicyclist interaction matrix ................................................................ 146 Figure 46 Expanded FCS pedestrian interaction matrix ............................................................ 151 Figure 47 Expanded FCS multimodal matrix by context and roadway type .............................. 154 Figure 48 Corridor example Expanded FCS application ........................................................... 158 Figure 49 Aerial views of corridor ends ..................................................................................... 160 Figure 50 Cross section, urban core ......................................................................................... 162 Figure 51 Aerial corridor view .................................................................................................... 163 Figure 52 Proposed cross section ............................................................................................. 165 Figure 53 Functional classification use by project development activity ................................... 168

x SUMMARY The modern Functional Classification System (FCS) was developed in the 1970s as a basis for communication between designers and planners. It sought to establish a common framework for classifying roadways based on mobility and access. Since its inception, the application of the FCS has expanded, and is now used throughout the entire project development process and influences all transportation project development phases, from programming and planning through design and into maintenance and operation decisions. However, the focus of the FCS is narrow; as it balances only mobility and access. The limited contextual definitions (urban and rural), do not provide the dynamic range of design elements and guidance needed to balance other competing project needs. The objective of this research is to develop a flexible framework that replaces the FCS and facilitates optimal geometric design solutions that take into account context, functions, and user needs. To develop this alternative classification system, a two-phased approach was employed. The first phase involved a literature review, a survey of transportation agencies/practitioners, identification of existing alternative systems, and an evaluation of those existing alternative systems and their components. Work during this phase identified promising elements to be considered for inclusion in the proposed system. In the second phase, the proposed alternative is fully developed, its implications for design are documented, and the effects on other areas are highlighted. The research team produced a new alternative classification system to aid designers in developing contextual designs that balance a range of user’s needs. The literature review indicated that the FCS has assumed additional significance beyond its intended purpose: as a framework to identify the particular role of a roadway that moves vehicles through a network of highways. While the FCS is essential in defining the roadway network and identifying design expectations of users, several issues can arise in its broader application. Even though the urban/rural classification is essential when assigning jurisdictional roles, operational needs, and funding allocation, it does not provide for the range of perspectives essential for successful contextual design. There have been efforts to understand the implications of functional classification on highway agency roadway projects, but the studies that dealt with the issue did not offer a systematic and/or a complete approach towards a unified treatment of the roadway classification. The recent development of Context Sensitive Solutions and Practical Design (i.e., the development of targeted solutions to address contextual design within fiscal constraints) necessitated the review of current practices and applications of the FCS due to its potential limiting effects on the development of appropriately contextual designs.

xi The research team’s survey of transportation agencies focused on: 1) establishing how the FCS is put into practice among agencies, and 2) identifying the implications and potential issues as they manifest in design. An additional goal was to identify any efforts that agencies have undertaken which have resulted in an alternative classification system. The 267 respondents confirmed the pervasiveness of the FCS in all phases of project development and noted the wide- ranging impacts. The participants also identified familiar issues with the FCS, including its lack of distinction for suburban roadways, the absence of further differentiation within urban areas, the want of recognition of “Main Streets” requiring considerations beyond mobility and access, the use of typical templates that do not reflect the true context, the emphasis on vehicular needs and lack of consideration of other competing modes, the lack of distinction between local and regional travel, and the disconnect between land use (existing and planned) and classification. Several agencies have developed alternative classification systems that address some of the issues noted above. Seventeen systems were identified and reviewed to determine elements that could be useful in establishing a range of options and in defining a new classification system. Seven of the systems are summarized, while a more thorough review and documentation of 10 systems was completed based on input from the Working Advisory Group. All systems have an expanded context definition, ranging from four to 11, and most have defined road functions that expand on the traditional three-tier approach of the arterial-collector-local system. The majority of these systems developed a matrix that correlates context and road types that in turn is tied to design elements (i.e., tables with values or design considerations, elements to be considered, and their range of values). For some systems, there is a third dimension in the classification where modal priorities or other factors such as jurisdiction and environmental aspects are considered. This is achieved by either the explicit inclusion for specific roadway types or through consideration within the design elements as modal priorities. A set of objectives for a new classification system was developed with the assistance of the Working Advisory Group. They were used to develop the proposed system and ensure the accomplishment of the project’s research goal. These objectives are: Primary: • Improved Context Definition • Ability for Multi-modal Prioritization (or balancing) Secondary: • Ease of Use • Ability to Directly Relate to the FCS (traditional)

xii • Ability to Differentiate within Rural and Urban Applications • Ability to Consider Project and System Level Needs The proposed Expanded Functional Classification System (Expanded FCS) balances the simplicity of the traditional urban-rural classification with the need for expanded context categories. In this document, the term roadway is considered to include all facilities intended for travel in the right-of-way (e.g., travel lanes, shoulders, bicycle lanes, sidewalks). Roadway Context Three primary factors are used to determine context for the Expanded FCS: • Density (existence of structures and structure types) • Land uses (primarily residential, commercial, industrial, and/or agricultural) • Building setbacks (distance of structures to adjacent roadways) The Expanded FCS categories and their primary factors are as follows: Category Density Land Use Setback Rural Lowest (few houses or other structures) Agricultural, natural resource preservation and outdoor recreation uses with some isolated residential and commercial Usually large setbacks Rural Town Low to medium (single family houses and other single purpose structures) Primarily commercial uses along a main street (some adjacent single family residential) On-street parking and sidewalks with predominately small setbacks Suburban Low to medium (single and multi-family structures and multi- story commercial) Mixed residential neighborhood and commercial clusters (includes town centers, commercial corridors, big box commercial and light industrial) Varied setbacks with some sidewalks and mostly off-street parking Urban High (multi-story, low rise structures with designated off-street parking) Mixed residential and commercial uses, with some intuitional and industrial and prominent destinations On-street parking and sidewalks with mixed setbacks Urban Core Highest (multi-story and high rise structures) Mixed commercial, residential and institutional uses within and among predominately high rise structures Small setbacks with sidewalks and pedestrian plazas

xiii It is appropriate to consider the future context that may be informed by comprehensive planning documents and/or area/district/corridor development plans. However, the viability of those plans must be tested against actual trends and implementation intent confirmed by a variety of stakeholders. Roadway Types Roadway types are defined based on their network function and connectivity. Existing roadway type names were utilized to allow for an easier transition to the proposed system as well as to retain consistency with existing programming and funding allocations and other uses of functional classification categories. The network is defined based on the national, regional, and local importance of the roadway. The connectivity identifies the types of activity centers and locales that are connected by the roadway. Key characteristics of each roadway type are defined below: Category Network Importance Typical Uses Interstates/ Freeways/ Expressways Corridors of national importance providing long distance travel • Limited access • Through traffic movements • Primary freight routes • May support transit networks • No pedestrian or bike traffic • Guided by FHWA Design Standards Principal Arterial Corridors of regional importance connecting large centers of activity • Through traffic movements • Longer distance traffic movements • Long haul public transit buses • Primary freight routes Minor Arterial Corridors of local importance connecting centers of activity • Connections between local areas and network principal arterials • Connections for through traffic between arterial roads • Access to public transit and through movements • Pedestrian and bike movements Collector Roadways providing connections between arterials and local roads • Carry traffic with trips ending in a specific area • Access to commercial and residential centers • Access to public transportation • Pedestrian and bicycle movements Local All other roads • Direct property access—residential and commercial • Pedestrian and bicycle movements It should be noted that Interstates/Freeways/Expressways are not addressed in the Expanded FCS and they are not included in the classification matrix since Federal Highway Administration (FHWA) standards govern their design.

xiv In addition to the vehicular roadway types, network functionality is defined independently by corridor for transit, freight, bicycle, and pedestrian users. The level of modal priority on the corridor is defined as High, Medium, or Low based on the importance of the link to the individual mode system, as well as to existing or potential demand on the corridor. Modal systems are then applied as overlays to the vehicular FCS (shown above) to allow comprehensive understanding of all needs permitting the designer to balance modal priorities in a constrained environment. The correlation of context and roadway types and overlays results in the functional classification matrix allowing for the development of a multi-modal contextual based design. In every cell of the matrix, the various users (drivers, bicyclists, and pedestrians) are defined and their balancing characteristics are provided. • Drivers: The metrics used to define the context-roadway interaction for drivers are the operating speed and the balance between mobility and access. • Bicyclists: The context-roadway interaction is defined based on bicycle network classification categories and the amount of separation from motorized traffic. • Pedestrians: The metrics used for the context-roadway interaction include volume of pedestrians using the facility and the required sidewalk width to accommodate them. Separation of the facility from the adjacent traffic is also considered. • Transit: Transit accommodations range from minor lane widening if necessary, to include bus pull offs and separate lanes and/or facilities for express routes. • Freight: Can typically be accommodated by establishing minimum lane widths, but also may be served with intersection treatments to ensure accommodated turning movements. The specific user-related design considerations that should be addressed when balancing their needs to deliver a contextually appropriate multimodal design are incorporated in the complete Expanded FCS matrix. This presents the treatment options for each user (driver, bicyclist, and pedestrian) and identifies the interactions along the context and roadway type continuums.

xv Proper contextual roadway designs require an understanding of the needs of the potential roadway users and of the function of the roadway within its current and expected future context. The Expanded FCS and associated design matrix can identify the preliminary requirements for proper consideration of roadway context and user needs. This approach provides the framework for determining user needs and ordering user levels on a given roadway. It assumes the planner/designer can develop alternative system/network strategies for meeting all user needs. This process can provide input and refinement to the purpose and need statement that establishes the specific safety and mobility needs for the design to be developed. In the end, the final balancing of facilities to accommodate user needs becomes part of the process of following project development principles for achieving context sensitive solutions.

xvi A significant amount of thought has gone into possible alternatives to the FCS. This has yielded the Expanded FCS matrix that addresses the range of perceived shortcomings of the existing FCS. The proposed Expanded FCS takes advantage of the available forethought and provides an innovative framework that brings together context, road type/function, and user needs to establish multimodal design guidance and considerations to achieve enhanced solutions that are context sensitive. The Expanded FCS is a comprehensive alternative that can fit a variety of situations and can be used for individual projects or adopted by agencies for use on all projects in all phase of project development. It can be readily applied in a systematic manner by jurisdictions that have a need to develop innovative design solutions and have experienced the limiting effect of the current FCS.

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TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 230: Developing an Expanded Functional Classification System for More Flexibility in Geometric Design, which documents the methodology of NCHRP Research Report 855: An Expanded Functional Classification System for Highways and Streets builds upon preliminary engineering of a design project, including developing the purpose and need.

In particular, NCHRP Web-Only Document 230 provides additional contexts beyond urban and rural, facilitates accommodation of modes other than personal vehicles and adds overlays for transit and freight.

Two case studies illustrating an application of the expanded system to actual projects are included.

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