Design Guide for Low-Speed Multimodal Roadways (2018) / Chapter Skim
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From page 40... ...
40 3.1 Performance for Multimodal Projects Performance measures promote informed decision making by relating community goals to the measurable effects of transportation investments. Key steps in developing performance measures are (1)
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Balancing User Performance in Low- and Intermediate-Speed Environments 41 available to assess the needs and service levels of non-motorized users have been more elusive and ultimately difficult to use. Capacity, LOS, delay and stops are easily applied to define and assess vehicular performance for a planned roadway, but no predefined set of performance metrics can fully describe the safety and mobility complexities that exist given the interrelationships that exist between and among modes in the right-of-way.
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42 Design Guide for Low-Speed Multimodal Roadways outcomes will address, at some level, the desired performance of the new or redesigned facility. Traditionally, these goals and outcomes have focused on the LOS and safety provided to motorized vehicles; more recently, both the LOS and QOS are being considered for all legal users of that facility, using a wide range of possible performance measures.
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Balancing User Performance in Low- and Intermediate-Speed Environments 43 Quality of Service Manual (TCQSM) , now in its third edition, focuses on the evaluation of transit facilities (Kittelson and Associates, Inc., et al.
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44 Design Guide for Low-Speed Multimodal Roadways The FHWA guidebook expands the concept of performance measures specifically for pedestrian and bicycle transportation and identifies a toolbox of 30 specific performance measures mapped to seven broader project goal categories: connectivity, economic, environment, equity, health, livability and safety. The guidebook notes that pedestrian and bicycle transportation are considered "critical to each of these goal categories, and many performance measures are useful in characterizing a community's transportation system's ability to further the community goals." The FHWA guidebook highlights the "universe of possibility" for pedestrian and bicycle performance measures, enabling communities at the local, regional and state levels to select from among these measures and "develop a performance management strategy that is tailored to their context and unique needs" (FHWA 2016c)
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Balancing User Performance in Low- and Intermediate-Speed Environments 45 Using the HCM 6th Ed. for pedestrian and bicycle analysis on urban streets can require significant data collection and analysis.
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46 Design Guide for Low-Speed Multimodal Roadways simulation models and its application to multimodal analyses and oversaturated conditions. In addition to providing a cost-effective and reliable approach to analysis, the guide provides a practical introduction to the detailed methodologies of the HCM." • AASHTO's Highway Safety Manual (HSM)
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Balancing User Performance in Low- and Intermediate-Speed Environments 47 greater than 5,000. The chapter includes arterials other than freeways without full access control with two- or four-lane undivided facilities, four-lane divided and three- and five-lane roads with center TWLTLs in urban and suburban areas.
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48 Design Guide for Low-Speed Multimodal Roadways construction and reconstruction of highways and streets, stakeholders and decision makers increasingly want reasonable measures of the effect of geometric design decisions on the facility's performance for all of its users. The report includes information that helps a designer develop the foundation for performance-based analysis to inform geometric design decisions, followed by applications guidance to incorporate performance-based analysis into project development and geometric design decisions.
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Balancing User Performance in Low- and Intermediate-Speed Environments 49 metrics, summarizes the relevant analytical methods and data sources, and illustrates the use of each measure by one or more transportation agencies. The ten profiled measures are: 1.
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50 Design Guide for Low-Speed Multimodal Roadways Resource Document User Facilities Combined (All Users) Vehicles Pedestrians Bicycles Shared- Use Path Transit Guidebook for Developing Pedestrian and Bicycle Performance Measures (FHWA 2016c)
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Balancing User Performance in Low- and Intermediate-Speed Environments 51 3.3.2 Projecting Future Multimodal Demand Forecasts of future user demand should reflect community and regional plans, changes in project context over the analysis period, and the project's purpose and need. Based on these considerations, a future conditions projection represents a technical analysis and policy consensus on the type and developed intensity of land use, future local and regional economic activity, presence of transit service, changes in transit service, the anticipated presence and needs of pedestrians and bicyclists, and other possible factors.
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52 Design Guide for Low-Speed Multimodal Roadways Seasonal adjustments to the counts may be needed to ensure the count data accurately represents the average annual conditions. Finally, future design year conditions are estimated by adding to or subtracting from the existing traffic volumes to account for any network changes, future projects and future changes in localized development and context.
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Balancing User Performance in Low- and Intermediate-Speed Environments 53 Planning and design of transportation projects will generally need turning movement counts (TMCs) at intersections, including heavy vehicle movements and automatic traffic recorder (ATR)
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54 Design Guide for Low-Speed Multimodal Roadways and transit access in the street and roadway system. As pedestrian and bicycle travel have increased over time (along with related crash and fatality rates)
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Balancing User Performance in Low- and Intermediate-Speed Environments 55 Exceptions to meeting the minimum accommodations follow the FHWA guidance on accommodating bicycle and pedestrian travel and identified best practices for providing multimodal accommodation. Accommodation is not necessary in the following cases: • Prohibited use.
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56 Design Guide for Low-Speed Multimodal Roadways project development, and that they "tend to require performance prediction tools that are typically not used by designers." The report uses these measures to quantify accessibility: driveway density, transit stop spacing, and presence of pedestrian and/or bicycle facilities. • Mobility.
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Balancing User Performance in Low- and Intermediate-Speed Environments 57 published research findings. Exhibits 3-5 and 3-6 address expected relationships for roadway segments and intersections.
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58 Design Guide for Low-Speed Multimodal Roadways • "Expected direct effects" are performance effects caused by the geometric design decisions that occur at the same time and place (e.g., a given horizontal curve radius will immediately affect expected crash frequency at the curve location) ; • "Expected indirect effects" are performance effects caused by the geometric design decision but occur either later in time (e.g., providing additional auto capacity induces more auto travel)
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Balancing User Performance in Low- and Intermediate-Speed Environments 59 previously defined transportation performance categories: (1) accessibility, (2)
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60 Design Guide for Low-Speed Multimodal Roadways * FHWA Speed Concepts: Informational Guide (Donnell et al.
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Balancing User Performance in Low- and Intermediate-Speed Environments 61 performance measures for vehicles can potentially negatively affect the QOS for pedestrians, bicyclists, or transit users. The trade-off that often occurs in providing additional vehicle capacity is increased speeds of motorized vehicles.
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62 Design Guide for Low-Speed Multimodal Roadways Facility Type Performance Measure Definition Geometric Design Elements Basic Relationship Potential Performance Trade-offs Evaluation Resources Urban/ Suburban Segment Pedestrian LOS A letter grade associated with the quality of travel experience for a pedestrian; based on HCM 2010 methodology Sidewalk and pedestrian facilities, width of pedestrian lanes, buffer from vehicle traffic, driveway density, crossing frequency Increasing width of pedestrian facility, increasing distance from vehicle traffic, decreasing driveway density, and increasing opportunities to cross a street improve pedestrian LOS Meeting performance metrics for pedestrians may degrade travel quality for other modes – e.g., on-street parking improves pedestrian LOS and degrades BLOS HCM 2010 Chapters 16 and 17 Urban/ Suburban Intersections Pedestrian LOS A letter grade associated with the quality of travel experience for a pedestrian; based on HCM 2010 methodology Crossing distance, traffic control delay Decreasing pedestrian crossing distance and delay to cross a street improves pedestrian LOS Meeting performance metrics for pedestrians may degrade travel quality for other modes HCM 2010 Chapters 16 and 17 Urban/ Suburban Segment BLOS A letter grade associated with the quality of travel experience for a bicyclist; based on HCM 2010 methodology Bicycle accommodation features, physical separation from motorized vehicle traffic, access points and density, on- street parking Increasing width of bicycle facility, decreasing driveway density, increasing separation from moving vehicle traffic, and removing on-street parking improve BLOS Meeting performance metrics for bicyclists may degrade travel quality for other modes HCM 2010 Chapters 16 and 17 Urban/ Suburban Intersections BLOS A letter grade associated with the quality of travel experience for a bicyclist; based on HCM 2010 methodology Traffic control, delay Decreased delay for bicyclists increases quality of travel experience Meeting performance metrics for bicyclists may degrade travel quality for other modes HCM 2010 Chapters 16 and 17 Urban/ Suburban Segments and Intersections Transit LOS A letter grade associated with the quality of travel experience for a transit rider; based on HCM 2010 methodology Transit accommodations/ facilities (presence of transit-only lane, bus pullout areas, bus merge/diverge lanes, bus queue jump lanes) Providing bus-only lane, queue jump lanes, merge/diverge lanes decreases bus travel time and improves transit rider quality of travel Incorporating transit-only features often comes at the expense of providing additional auto or bicycle capacity or treatment HCM 2010 Chapters 16 and 17 Urban/ Suburban Segments and Intersections Auto LOS Number and duration of stops along an urban/ suburban corridor Number of travel lanes; intersection form, control type, and features Reducing the no.
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Balancing User Performance in Low- and Intermediate-Speed Environments 63 3.6 Multimodal Project Design Development Process Numerous approaches and processes exist for developing a street or roadway project design that effectively serves all users. Each transportation agency will normally have its own design process and procedures based on factors such as project cost, funding source, type of project (e.g., new construction; reconstruction; and resurfacing, restoration and rehabilitation, often called "3R")
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64 Design Guide for Low-Speed Multimodal Roadways design. If a locally funded project is located on a facility owned by another agency (such as a state or federal-aid facility owned by a state DOT)
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Balancing User Performance in Low- and Intermediate-Speed Environments 65 project team for this Guide suggests that elements of this approach can be used for the design of all low- and intermediate-speed roadway types under any context. • Stage 1: Review area transportation plans.
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66 Design Guide for Low-Speed Multimodal Roadways Stage 3 also involves close examination of all modal requirements (e.g., transit, bicycle, pedestrian and freight needs) and establishes design controls such as design traffic volumes for all users, speed, corridor-wide operations, right-of-way constraints and other fundamental engineering controls.
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Balancing User Performance in Low- and Intermediate-Speed Environments 67 This stage also is iterative, resulting in one or more cross sections for various segments of the project. Stage 5 leads into the preliminary and final engineering steps, which include: – Identifying the available right-of-way, desired right-of-way and any constraints; – Designing the traveled way and roadside elements, including an evaluation of trade-offs as may be necessary if right-of-way is constrained; – Designing the street-side elements, which requires an understanding of the characteristics and activity of the adjacent existing or future context; and – Assembling the roadway components -- an iterative process, particularly in constrained rights-of-way, to balance LOS and QOS to all modes.
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68 Design Guide for Low-Speed Multimodal Roadways 3.6.4 Applying the Six-step USDG Process Three assumptions are built into the USDG six-step process (City of Charlotte 2007b)
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Balancing User Performance in Low- and Intermediate-Speed Environments 69 The following questions regarding the intensity and arrangement of existing and future land uses in the area surrounding the street to be designed should be addressed by the plan/design team: • What does the area look like today? • What are today's land use mixtures and densities?
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70 Design Guide for Low-Speed Multimodal Roadways In addition to the general intent of providing complete streets, the following issues should be considered in defining the specific objectives: • What existing policies might or should influence the specific objectives for the street? • What conditions are expected to stay the same (or, more importantly, what conditions should stay the same)
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Balancing User Performance in Low- and Intermediate-Speed Environments 71 The steps outlined in Charlotte's USDG suggest that there is a linear process leading to an ideal solution. Realistically, in some instances the process may not follow the exact sequence described above.
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72 Design Guide for Low-Speed Multimodal Roadways • Step 7: Designing the geometric alternatives, which involves – Assembling an inclusive and interdisciplinary team, – Focusing on and addressing the need (or solving the problems) within the project's context conditions and constraints.
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From page 73... ...
Balancing User Performance in Low- and Intermediate-Speed Environments 73 inconsistencies or constraints. The Complete Streets guidelines note that solutions within various alternative scenarios will likely vary by cost, right-of-way needs and/or how various modes are accommodated, and that, preferably, these variations will require an evaluation and description of trade-offs before selection of the recommended alternative.
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From page 74... ...
74 Design Guide for Low-Speed Multimodal Roadways of the examples demonstrate an operational level analysis, and the fifth example demonstrates a planning-level analysis. The planning and preliminary engineering analysis is identical to the operational-level analysis in terms of the calculations, except that default values are used when field-measured values are not available.
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Balancing User Performance in Low- and Intermediate-Speed Environments 75 (or the predominant) roadway width can be phased in over time, beginning with the functional or absolute minimum design in the initial phase.
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