Design Guide for Low-Speed Multimodal Roadways (2018)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

3 1.1 Purpose, Objectives and Organization of the Guide 1.1.1 Purpose Before automobiles evolved in the 20th century, streets and roads primarily served a mix of slow-moving pedestrians, bicycles, horses and wagons in a manner that facilitated interaction with adjacent land uses. As motorized vehicles evolved and their ownership and usage grew, many roadways began to be designed to separate the motorized vehicle mobility function from the economic and social functions of adjacent businesses and neighborhoods. Roadway design priorities became increasingly focused on moving motorized vehicles as fast and efficiently as possible with decreasing attention to serving the lower numbers of non-motorized users using the right-of-way, even in urban contexts where the non-motorized users remained a significant presence. For many of today’s street and roadway facilities, especially those in urban and suburban contexts, accommodation of walking and bicycling requires retrofitting the motorized vehi- cle dominant transportation network to provide new or enhanced pedestrian and bicycle infrastructure. These facilities also often exist in constrained rights-of-way. This requires a greater awareness of the flexibility and versatility available in national guidance to help designers overcome many challenges related to retrofit and new alignment projects. Designers must also manage conflicts between all modes as an important element of the inclusion pro- cess. Pedestrians are the most vulnerable roadway user because they are at the greatest risk of injury or death in a collision with someone traveling by any other mode. Bicyclists generally travel at slower speeds than motorized vehicles and are inherently more vulnerable in the event of a crash with a car, truck, or transit vehicle. Designers need practical information and guidance based on real-world scenarios to address a variety of conflicts that can occur between different modes. NCHRP Research Report 880: Design Guide for Low-Speed Multimodal Roadways (the Guide) has been developed in response to these real design challenges and a growing national interest in improving both the safety and mobility for non-motorized users in the right-of-way (i.e., pedes- trians, bicyclists and transit riders). This growing focus is especially prevalent in the low- and intermediate-speed corridors of urban and suburban areas. Additionally, many cities, counties and state agencies are striving to improve the character of their roadways through a commit- ment to creating more integrated transportation networks that result in more walkable, bike- able and transit-friendly communities and regions. Design professionals can better achieve these goals by applying the concepts and principles in the Guide to ensure that all roadway users, the community and other key considerations are properly considered in the geometric design process. C H A P T E R 1 Introduction

4 Design Guide for Low-Speed Multimodal Roadways This Guide provides designers, planners and policy makers with information on designing safer, more comfortable, and accessible roadway facilities so that walking and biking are safer and more convenient transportation choices for all users. It identifies and addresses common concerns and perceived barriers among design professionals concerned about liability when designing pedestrian and bicycle facilities, and directs them to the most current national guidance that provides specific information on multimodal design treatments and approaches. U.S.DOT policy encourages agencies and designers to consider and address the needs of pedes- trians and bicyclists in the provision of all transportation facilities. U.S.DOT guidance to improve pedestrian and bicycle accommodation is provided in Accommodating Bicycle and Pedestrian Travel: A Recommended Approach, which can be found at the Federal Highway Administration’s (FHWA) Bicycle and Pedestrian Program website (https://www.fhwa.dot.gov/environment/ bicycle_pedestrian/guidance/design.cfm). The “Policy Statement” section of the website includes the following sections: 1. Bicycle and pedestrian ways shall be established in new construction and reconstruction projects in all urbanized areas unless one or more of three conditions are met: • Bicyclists and pedestrians are prohibited by law from using the roadway. In this instance, a greater effort may be necessary to accommodate bicyclists and pedestrians elsewhere within the right-of-way or within the same transportation corridor. • The cost of establishing bikeways or walkways would be excessively disproportionate to the need or probable use. Excessively disproportionate is defined as exceeding twenty percent of the cost of the larger transportation project. • Where sparsity of population or other factors indicate an absence of need. For example, the Portland Pedestrian Guide requires “all construction of new public streets” to include sidewalk improvements on both sides, unless the street is a cul-de-sac with four or fewer dwellings or the street has severe topographic or natural resource constraints. 2. In rural areas, paved shoulders should typically be included in all new construction and reconstruction projects on roadways used by more than 1,000 vehicles per day. Paved shoulders have safety and operational advantages for all road users in addition to providing a place for bicyclists and pedestrians to operate. Rumble strips are not recommended where shoulders are used by bicyclists unless there is a minimum clear path of four feet in which a bicycle may safely operate. 3. Sidewalks, shared use paths, street crossings (including over- and under-crossings), pedestrian signals, signs, street furniture, transit stops and facilities, and all connecting pathways shall be designed, constructed, operated and maintained so that all pedestrians, including people with disabilities, can travel safely and independently. 4. The design and development of the transportation infrastructure shall improve conditions for bicycling and walking through the following additional steps: • Planning projects for the long-term. Transportation facilities are long-term investments that remain in place for many years. The design and construction of new facilities that meet the criteria in item (1) above should anticipate likely future demand for bicycling and walking facilities and not preclude the provision of future improvements. For example, a bridge that is likely to remain in place for 50 years might be built with sufficient width for safe bicycle and pedestrian use in anticipation that facilities will be available at either end of the bridge even if that is not currently the case. • Addressing the need for bicyclists and pedestrians to cross corridors as well as travel along them. Even where bicyclists and pedestrians may not commonly use a particular travel corridor that is being improved or constructed, they will likely need to be able to cross that corridor safely and conveniently. Therefore, the design of intersections and interchanges shall accommodate bicyclists and pedestrians in a manner that is safe, accessible and convenient. • Getting exceptions approved at a senior level. Exceptions for the non-inclusion of bikeways and walkways shall be approved by a senior manager and be documented with supporting data that indicates the basis for the decision. • Designing facilities to the best currently available standards and guidelines. The design of facilities for bicyclists and pedestrians should follow design guidelines and standards that are commonly used, such as the AASHTO Guide for the Development of Bicycle Facilities [AASHTO 2014b], AASHTO’s A Policy on Geometric Design of Highways and Streets [AASHTO 2011a], and the ITE’s Design and Safety of Pedestrian Facilities [ITE 1998].

Introduction 5 The Guide will help designers and planners better understand and facilitate the often complex multiple functions of modern urban and suburban streets. It provides guidance for the design of multimodal streets and roadways where all motorized and non-motorized modes must co-exist in places where community goals are aimed to provide a more balanced approach to accom- modating the safety and mobility of all user modes. The Guide summarizes the flexibility and versatility available in existing national design guidance. It also addresses how a designer can reduce liability concerns through proper application of engineering judgment, design process documentation, and experimentation when justified. The Guide builds on that foundation by introducing guiding principles for reducing conflicts between modes. 1.1.2 Objectives and Organization The objectives of this Guide are to: 1. Identify techniques and approaches for how street and roadway design processes should accommodate and integrate all users on urban and suburban facilities and within the built-up areas of small villages and towns; 2. Describe the relationship, compatibility and trade-offs in selecting design controls, criteria and elements that may be appropriate when balancing the needs of all users, adjoining land uses, environment and community interests when making decisions in the project design process; 3. Describe the principles of context-sensitive solutions (CSS) and the benefits and importance of these principles in designing transportation projects for all users; and 4. Present guidance on how to identify and select appropriate design parameters and criteria to best meet the needs of all legal users that exist in a particular context setting. The Guide addresses three specific realms of multimodal design: design of the traveled way, design of roadsides and design of intersections. These topics and supporting information are addressed in six chapters: • Chapter 1 provides an overview of the document that includes its purpose, objectives and structure; • Chapter 2 outlines and discusses the design considerations for all user groups and their inter- relationships in low- and intermediate-speed contexts; • Chapter 3 addresses the process of assessing and balancing service levels among all user modes in low- and intermediate-speed contexts; • Chapter 4 provides specific criteria and guidance for designing all aspects of the traveled way of integrated multimodal streets, roads and intersections across a range of types, speeds and land use contexts; • Chapter 5 provides specific criteria and guidance for designing all aspects of the roadside of integrated multimodal streets and roads across a range of types, speeds and land use contexts; and • Chapter 6 provides design examples that illustrate the process of considering and selecting design elements, controls and criteria in different context settings. 1.2 Intended Users This Guide is intended for design practitioners and stakeholders involved in the planning and design of streets and roadways that serve a mix of motorized and non-motorized users on facili- ties designed for low- and intermediate-speed ranges of 45 miles per hour (mph) and below. Users of the document are encouraged to consider the principles and guidelines presented in conjunction with applicable local policies and manuals.

6 Design Guide for Low-Speed Multimodal Roadways Although design practitioners will likely be the predominant user of the document, it is expected that other professional disciplines engaged in the street and roadway design process, including transportation planners, traffic engineers, land use and community planners, urban designers and landscape architects, may also find the Guide useful. Each of these groups will often represent a different set of perspectives and responsibilities to the project development process that best addresses the needs of their stakeholders to be served by the final design solutions. 1.3 Range of Facilities Addressed Designing streets and roads that effectively and safely serve all legal users of the right-of-way is a crucial responsibility of all designers and transportation agencies with roadway design responsibilities. The level of service (LOS) and quality of service (QOS) to any mode can vary greatly depending on a range of factors that include the relative volumes of each mode, the facility’s desired functional classification within the street network, existing and desired vehicle operating speeds, right-of-way dimensions and geometry, and the context of the project area. Although the concepts and principles of CSS can be applied to all types of transportation facili- ties in all contexts, the Guide focuses on applying the concepts and principles to the planning and design of low- and intermediate-speed streets and roadways that typically exist in urban and suburban areas, as well as low-speed rural areas such as the built-up areas of rural villages and towns. NCHRP Research Report 855: An Expanded Functional Classification System for High- ways and Streets reflects the context zone approach developed in NCHRP Project 15-52 to assist designers in applying geometric design flexibility (Stamatiadis et al. 2017). Four of the five context zones developed in that project are used as a foundational element of this Guide. Within these contexts, the guidelines focus on facilities where a mix of motorized and non- motorized users is most likely and where designing for them is most challenging. Typically, these facilities will include the conventional functional classifications of primary and minor arterials, major and minor collectors, and local roadways in urban, suburban and rural villages/towns. These facilities, especially arterial and collector facilities, often serve significant volumes of higher-speed motorized traffic that must co-exist with increased levels of non-motorized users and transit service. Although freeways, expressways and major high-speed (50 mph and higher) arterials certainly exist in urban and suburban areas, design of these facilities is not addressed in this Guide. The table in Exhibit 1-1 summarizes the combination of roadway facility types, speed ranges and land use contexts addressed in the Guide. Given their typical low level of mul- timodal activity, roadways in rural undeveloped contexts are not the focus of these guidelines, but many of the design elements and approaches presented herein may be appropriate when non-motorized travel exists on those facility types. Functional Classification Design Speed Area Type and Predominant Context Rural Urban Undeveloped Village, Town, Built-up Areas Urban Core General Urban Suburban Principal and Minor Arterial ≤ 45 mph X X X X ≥ 50 mph Major and Minor Collector ≤ 45 mph X X X X ≥ 50 mph Local ≤ 45 mph X X X X ≥ 50 mph Exhibit 1-1. Roadway facility types addressed in this Guide.

Introduction 7 1.4 Project Development and Design Process to Address All Users The development process for roadway improvement projects in urban, suburban and low- speed rural areas may begin in the programming, planning or environmental processes of a transportation program. The ultimate ability of a project designer to provide a design that ade- quately considers and serves all legal users of a facility can depend on the decisions made during those early phases. It is important to ensure that necessary right-of-way, funding and contextual relationships are understood and considered. Too often, improvement projects have been con- ceived only on the future projection of motorized vehicle needs. This approach lacks an under- standing and consideration of the current and future needs of the other users of the facility, the future context of the project area, and the community and neighborhood goals for the project. The long-range transportation planning process provides an opportunity to identify those facilities and places where local agency land use and development policies benefit from and sup- port context-sensitive roadway design (e.g., pedestrian-scale districts, town or village center designs, bicycle-priority facilities and transit corridors). The broader policy decisions can influ- ence the development of appropriate roadway classifications and their design elements and dimensions. Multidisciplinary team and stakeholder involvement also are critical in the early phases of the design process. The fundamentals of urban and suburban context-sensitive design are addressed in Chapter 2, the modal priority-balancing process is the focus of Chapter 3 and the recommended design guidance framework is addressed in Chapters 4 and 5. The project design concept should emerge from an understanding of the relationships between roadway classification and context types, along with other unique project circumstances, values or objectives. Additionally, a roadway’s modal emphasis should ideally be identified in the early project concept development phases. The Guide provides tools for aligning various roadway types and speed conditions to various modal demands and contexts. It describes how to pri- oritize design elements and assemble the cross sections and intersection design features based on context and potentially constrained conditions. Data input to the project concept phase of project development should include information relating to the current and future use of all modal users, land use development patterns and design features that support present conditions. Equally important is the design team’s vision for the project’s future context. An important step in project planning phase involves development and analysis of design alternatives, including an environmental review. Alternatives may be developed using the techniques and design criteria presented in the Guide, including accessibility. Each alternative should incorporate appropriate design characteristics that are compatible with the context of the facility and community. The preliminary engineering and final design phases should be driven by carefully selected design controls and detailed guidelines. The Guide provides information to establish an initial design for testing, identify trade-offs and prepare a final concept for engineering. It bears repeating that applying the information presented in the Guide requires an under- standing of both the existing context and the future context of the project area. The application of context-sensitive principles also requires the designer to know how to use the design of the roadway/facility to support existing and planned adjacent land uses and development patterns. 1.5 Applicability The information in this Guide can be applied to designing low- and intermediate-speed roadways of all functional classifications that safely and effectively serve legal users of all ages and abilities, both present and planned, in urban and suburban contexts and built-up areas of villages and towns.

8 Design Guide for Low-Speed Multimodal Roadways Most applications of the guidance provided herein will occur in the context of (1) a roadway project in an existing community where the roadway’s multimodal character is to be preserved and enhanced, or (2) a roadway project in an area where community goals call for a multimodal context. In the latter case, applying this design guidance will shape public investment to advance those goals. Both circumstances can apply to either new construction or retrofit projects. Projects in all community and development contexts will benefit from applying the guid- ance presented in this Guide. In areas such as central business districts, suburban business parks, residential subdivisions and strip commercial development, the Guide can help designers pro- vide benefits that include: • Safe, comfortable, accessible facilities for pedestrians and bicyclists; • Safe and convenient access to transit; • Aesthetically pleasing roadside and median areas; • Appropriate sizing of facilities with respect to pavement width, with associated potential for cost savings in right-of-way acquisition, construction and maintenance; • Successful integration of transit facilities and operations; and • Management of vehicle speed appropriate to the context. 1.6 Relationship to Other Design Guidance The Guide supplements and expands on policies, guides and standards commonly used by state and local transportation, engineering and public works engineers and planners. Frequently referenced publications include: • A Policy on Geometric Design of Highways and Streets (AASHTO 2011a); • Guide for the Planning, Design and Operation of Pedestrian Facilities (AASHTO 2004b); • Guide for the Development of Bicycle Facilities (AASHTO 2014b); • Highway Safety Manual (AASHTO 2010); and • Roadside Design Guide (AASHTO 2011b). This Guide also refers to state and federal department of transportation design policies and manuals, local municipal street design standards, urban design guides and guidance published by other organizations such as the Institute of Transportation Engineers (ITE) and National Association of City Transportation Officials (NACTO). The Guide expands on information published by FHWA and AASHTO in Flexibility in High- way Design (FHWA 1997), A Guide for Achieving Flexibility in Highway Design (AASHTO 2004a), and in the Manual on Uniform Traffic Control Devices, or MUTCD (FHWA 2009b). Another FHWA publication, Achieving Multimodal Networks: Applying Design Flexibility and Reducing Conflicts (FHWA 2016a), continues to build upon the considerations in developing roadway designs that are context sensitive and result in safe and effective multimodal designs. The Guide helps illustrate how current AASHTO guidance can be applied to roadway improvement proj- ects to make them more accommodating for all users, community objectives and surrounding context on low- and moderate-speed facilities in urban and suburban areas. The flexibility encouraged by the Guide is consistent with the policies and intent expressed in the Green Book (AASHTO 2011a). Most of the criteria in the Guide are based on current AASHTO design criteria, and this report shows how the criteria can be applied to create road- way geometric designs that effectively serve all users in low- and moderate-speed contexts. The Guide also presents information from sources other than AASHTO. All sources cited are col- lected in the References section following the chapters. By reference, this report also incorporates consistency with guidelines and standards published in the latest versions of the Americans with

Introduction 9 Disabilities Act Accessibility Guidelines (ADAAG) (U.S. Access Board 2002) and the Proposed Guidelines for Pedestrian Facilities in the Public Right-of-Way (PROWAG) (U.S. Access Board 2011). The latter two documents are available online at www.access-board.gov. Augmenting information found in the above resources, the Guide also addresses: • Providing safe and convenient accommodation of all legal modes in project design; • Applying context-sensitive principles in the design of low- and intermediate-speed roadways; • Considering a broader set of factors during the design of multimodal roadways; • Recognizing the importance of context, the role of sites and buildings and how context influences the design of the roadway and vice versa; and • Providing an understanding of how roadway design criteria can, and should, vary depending on the context through which the roadway passes. Some devices and applications discussed in the Guide are covered under Interim Approvals in the MUTCD (FHWA 2009b). Examples include green-colored pavement in bicycle lanes and rectangular rapid-flash beacons. FHWA approval must be obtained before these devices can be installed. Sources of Additional Information FHWA. 2011. Livability in Transportation Guidebook: Planning Approaches that Promote Livability. Federal Highway Administration, U.S. Department of Transportation, Washington, D.C. Online: https://www.fhwa.dot.gov/livability/ case_studies/guidebook/livabilitygb10.pdf. FHWA. 2015f. Separated Bike Lane Planning and Design Guide. Publication Number: FHWA-HEP-15-025. Federal Highway Administration, U.S. Department of Transportation, Washington, D.C. Online: https://www.fhwa.dot.gov/ environment/bicycle_pedestrian/publications/separated_bikelane_pdg/ page00.cfm. NACTO. 2016. Transit Street Design Guide. National Association of City Transportation Officials, New York. Online: https://nacto.org/publication/ transit-street-design-guide/. TRB. 2010. Highway Capacity Manual (HCM). Transportation Research Board of the National Academies, Washington, D.C. TRB. 2016b. Highway Capacity Manual, 6th Ed.: A Guide for Multimodal Mobility Analysis (HCM). Transportation Research Board of the National Academies, Washington, D.C.