An Expanded Functional Classification System for Highways and Streets (2018) / Chapter Skim
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Pages 26-38
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From page 26... ...
26 Modal Considerations and Accommodation The following sections discuss issues associated with users and present design considerations for each mode in order to achieve a contextual design solution. The Expanded FCS matrix is also presented along with considerations for transit and freight overlays.
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From page 27... ...
Modal Considerations and Accommodation 27 Access and Mobility The typical tradeoff between access and mobility presented in the existing classification system is enhanced in the Expanded FCS to reflect the influence of roadway and context as they change across the various matrix categories. Access is defined as the frequency of driveways or intersections and is grouped in three categories based on distance between access points: low (>0.75 mile)
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28 An Expanded Functional Classification System for Highways and Streets the greater need for access for local roads. The target speed also changes among the categories, with an increasing trend from local to arterial roads.
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Modal Considerations and Accommodation 29 Design Considerations The primary design characteristic for drivers is mobility. However, because roadways may have other modal traffic, the level and type of separation from vehicles provided for the other users may also need to be considered.
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30 An Expanded Functional Classification System for Highways and Streets The Expanded FCS matrix identifies a proposed level of separation that may be considered for each bicycle facility category according to roadway type and context. Potential treatments that may be included within each of these separation levels are as follows: • Low/No-separation treatments – No specific treatment, for cases with rare or occasional bicycle traffic.
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Modal Considerations and Accommodation 31 Bicycle facility class: CC = citywide connector, NC = neighborhood connector, LC = local connector Separation level: H = high, M = medium, L = low Figure 22. Expanded FCS bicyclist interaction matrix.
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32 An Expanded Functional Classification System for Highways and Streets Design Considerations Sharrows with narrow lanes may be used when the narrow lane would not cause safety concerns or exceptionally delay traffic flow, including in the following cases: • Small speed differences between bicycles and vehicles. • Low volume of vehicular or bicycle traffic.
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Modal Considerations and Accommodation 33 Access density is also a consideration with bicycles, especially with cycle tracks and buffered bike lanes. In areas of high access density, the separation of bicycle traffic should be avoided because it increases the number of crossing conflicts for ingress and egress traffic.
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34 An Expanded Functional Classification System for Highways and Streets The need for variations in width may be demonstrated by examining two extreme examples. First, consider a high-speed urban arterial that also serves as a connector between large centers of activity (e.g., a university campus and the downtown area)
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Modal Considerations and Accommodation 35 high-speed roadways do require increased separation of pedestrian facilities and the travel way of the road. The complete interaction of the Expanded FCS matrix and pedestrian facility width is shown in Figure 24.
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36 An Expanded Functional Classification System for Highways and Streets Increased tree lawns, shielding, or physical separations could be used as buffers, and, in extreme cases, off-roadway paths may provide the best pedestrian experience. To determine the pedestrian LOS when buffers are used, the designer needs to take into account the reduction to the effective facility width due to the presence of the separation (e.g., trees, shrubs, or grass)
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Modal Considerations and Accommodation 37 turning radii to accommodate transit vehicles. While low-order transit routes and infrequent turns may not require special accommodation, higher-priority routes for transit should have smooth turning radii to minimize unnecessary delays at turns.
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38 An Expanded Functional Classification System for Highways and Streets Freight Accommodation as an Overlay Freight routes may not require significant additional facilities beyond those provided for vehicular traffic, if mobility and speeds of vehicular routes are consistent with freight movement. However, curbside lanes should be designed to accommodate the width of the design freight vehicle -- typically resulting in lane widths of 11–12 feet.
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