Design Guide for Low-Speed Multimodal Roadways (2018) / Chapter Skim
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Pages 10-39
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10 This chapter addresses a wide range of design considerations for low- and intermediate-speed (45 mph or less) roadways and streets that serve a mix of user modes, particularly the vulnerableuser modes of pedestrians and bicyclists.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 11 • Pedestrians and bicyclists; • Safety; • Environment; and • Economic analysis. The Green Book also addresses the alignment and cross section of roadways and notes its impact on users, communities and the environment.
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12 Design Guide for Low-Speed Multimodal Roadways In addition, FHWA's Highway Functional Classification: Concepts, Criteria and Procedures recognizes the challenges in balancing the goals of a facility's functional classification with the land use context and mix of users that may be present (FHWA 2013b) : After a functional classification has been assigned to a roadway, however, there is still a degree of flexibility in the major controlling factor of design speed.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 13 2.2.3 Design Factors that Influence Target Operating Speed Establishing a target speed that is artificially low relative to the design of the roadway will only result in operating speeds that are higher than desirable and difficult to enforce. Consistent with AASHTO policy, the Guide urges sound judgment in the selection of an appropriate target operating speed based on a number of factors and reasonable driver expectations.
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14 Design Guide for Low-Speed Multimodal Roadways require the design to accommodate the largest design vehicle that could use a roadway (e.g., WB 50 to WB 67) , regardless of the frequency.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 15 This Guide also expands the variation in design elements controlled by location to include predominant ground floor land uses such as residential, commercial, school, park and so forth. Land uses (existing and planned/future)
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16 Design Guide for Low-Speed Multimodal Roadways a person's mobility, judgment, sight, or hearing, however, providing proper design solutions becomes much more important. The pedestrian user category includes four generally accepted and distinct classes: • Able-bodied pedestrians with average or better agility; • Pedestrians with mobility, vision or hearing disabilities; • Older pedestrians with limited functions and/or mobility; and • Younger pedestrians with more erratic behavior and generally smaller stature.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 17 Bicycle facilities take many forms, including signed routes, shared lanes with motorized vehicles, on-street striped bike lanes, on-street buffered bike lanes, separated bike lanes and bike paths/trails that are separated from motorized vehicle lanes or from the roadway altogether. Other bicycle facilities in the right-of-way may include intersection and non-intersection crossing locations, special traffic control signals, special roadway markings and bicycle parking accommodations.
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18 Design Guide for Low-Speed Multimodal Roadways • Network planning should address multimodal mobility and access needs along with goods movement, utilities placement and emergency services. • Reserving right-of-way for the ultimate width of roadways should be based on long-term needs of all users defined by objectives for both community character and mobility.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 19 category: boulevards, avenues, streets and rural roads. These roadway thoroughfare types typically serve a mix of modes, including pedestrians, bicyclists, motorized vehicles (for passenger and freight)
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20 Design Guide for Low-Speed Multimodal Roadways 2.6 Modes: Separation, Integration and Conflict Reduction When multiple user modes (e.g., pedestrians, bicyclists, transit, and motorized vehicles) operate in the same right-of-way, conflicts can and do occur.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 21 The management of conflict points should consider and incorporate access to current and future adjacent land uses. Designs should minimize barriers to walking, bicycling, and transit use, and promote improved economic, social and public health.
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22 Design Guide for Low-Speed Multimodal Roadways function of a road; as land use changes along a road, the road's functions also change. Roadways should be designed to serve the existing land use while supporting the corridor and the community's future land use goals.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 23 Stamatiadis et al.
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24 Design Guide for Low-Speed Multimodal Roadways Applying the principles of context-sensitive design enhances the geometric design process by addressing objectives and considerations not only for the transportation facility but also for the surrounding area and its land uses, developments, economic and other activities and environmental conditions. With a thorough understanding of the context-sensitive principles and design process, the practitioner designing a roadway can integrate community objectives, accommodate all users and make decisions based on an understanding of the trade-offs that frequently accompany multiple or conflicting needs.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 25 Broadly speaking, context can consist of an urbanized built environment, part of the natural environment, or both. The built environment consists of properties and activities within and adjacent to the public right-of-way -- and the roadway itself -- with surroundings whose characteristics help to define the context within that zone.
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26 Design Guide for Low-Speed Multimodal Roadways 2.9.3 The Traveled Way as a Design Element The public right-of-way between curbs includes parking lanes and the travel lanes for vehicles, goods movement, transit vehicles and bicycles. The traveled way includes medians, turn lanes, transit stops, exclusive transit lanes, the curb and gutter and loading/unloading zones.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 27 so much of a highway's design, the choice of a design speed is fundamental and significant. The selected design speed should be high enough so that an appropriate regulatory speed limit will be less than or equal to it.
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28 Design Guide for Low-Speed Multimodal Roadways 2.11 Speed Management as a Design Goal Transportation safety is not only about motorized vehicle safety; it also encompasses protecting vulnerable users. Setting safe, consistent and reasonable target speed limits is the first step in speed management and is important in order to reasonably accommodate and protect all roadway users.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 29 delineation, dynamic signing and access controls. More than 100 references detail the effectiveness of these engineering countermeasures.
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30 Design Guide for Low-Speed Multimodal Roadways be applied to private driveways that have public roadway-like features. The report does not address speeds on roadway segments outside the influence area of an intersection, but it does discuss the relationship between segment speed and speed within the intersection influence area.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 31 – The AASHTO Highway Safety Manual (HSM, AASHTO 2010) ; and – The National Association of City Transportation Officials (NACTO)
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32 Design Guide for Low-Speed Multimodal Roadways 6th Ed. does not establish a legal standard, but it provides guidance on techniques to analyze various modes of traffic.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 33 design decisions. For any roadway on the NHS, FHWA required a formal written design exception if any of these 13 design criteria were not met.
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34 Design Guide for Low-Speed Multimodal Roadways states can determine their own level of documentation and may adopt policies that are more restrictive than the FHWA policy outlined above. FHWA also encourages agencies to work with stakeholders "to develop context-sensitive solutions that enhance communities and provide multiple transportation options to connect people to work, school, and other critical destinations" (81 Fed.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 35 also may be required. Documenting design decisions is a required component of the design exception process.
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36 Design Guide for Low-Speed Multimodal Roadways resurfacing, widening, and projects of similar scale and effect. Without curb ramps, sidewalk travel in urban areas can be dangerous, difficult, or even impossible for people who use wheelchairs, scooters, and other mobility devices.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 37 2.16 Considerations for Bridges and Other Structures Bridges are key components of any transportation network, particularly for pedestrian and bicycle networks in urban and suburban areas. They often are the only way for all modes to travel across natural obstacles (rivers, ravines)
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38 Design Guide for Low-Speed Multimodal Roadways 2.17 Coordination with Stormwater and Green Infrastructure FHWA estimates that about 35 percent of U.S. roads are located in urban areas.
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Design Considerations for All Users in Low- and Intermediate-Speed Environments 39 Permeable Pavement Permeable pavement comes in four forms: permeable concrete, permeable asphalt, permeable interlocking concrete pavers, and grid pavers. Permeable concrete and asphalt are similar to their impervious counterparts but are open graded or have reduced fines and typically have a special binder added.
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