National Academies Press: OpenBook

Guidance to Improve Pedestrian and Bicyclist Safety at Intersections (2020)

Chapter: Chapter 6: Final Countermeasure Selection

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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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Suggested Citation:"Chapter 6: Final Countermeasure Selection." National Academies of Sciences, Engineering, and Medicine. 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC: The National Academies Press. doi: 10.17226/25808.
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83 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Chapter 6: Final Countermeasure Selection This chapter provides a more in-depth look at some of the components related to project framing (Chapter 1), and builds on the processes for identifying an initial list of potential countermeasures (Chapter 4) and refining those countermeasures based on the project context (Chapter 5). While a long list of eligible countermeasures may be refined through thoughtful consideration of the project context, practitioners must also be able to prioritize competing projects, implement countermeasures that have public support, and justify their decisions after implementation. This chapter details a process to identify the right safety treatment or countermeasures to improve multimodal safety for the identified issue and context. This process will help the practitioner assess the trade-offs associated with potential countermeasures as part of making a final selection. Chapter 5 emphasized that design decisions are not made in isolation. While assessing the project context, user needs, and potential safety countermeasures are important first steps in the intersection design process, it is important to recognize that intersection design affects every roadway user. These effects generally involve trade-offs between safety, access, and mobility outcomes for the different travel modes. When selecting a particular treatment out of a range of possibilities, practitioners and decision-makers must balance multimodal performance within a physically, economically, and politically constrained space. The final steps in the safety identification process involves identifying the tradeoffs and viability of the remaining potential countermeasures following the refinement process described in Chapter 5. These steps includes • Operations, safety, and comfort prioritization (Section 6.1); • Local and regional regulations, policies, and funding (Section 6.2); and • Benefit–cost analysis (Section 6.3). Identify Treatment Options for Creating Safer Intersections Countermeasure Options 45 Frame the Process Analyze Intersection Safety and Identify Issues Identify and Collect the Data for Analysis 1 2 3Chapter Chapter Chapter Chapter Chapter Evaluate Priorities and Assess Trade-Offs and Viability 6 Final Countermeasure Selection 6 ChapterChapter

84 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS These steps can fit within an agency’s larger process for identifying design solutions. Each step requires a varying degree of public or political support which will need to be considered. Section 6.4 provides an example process for identifying flexible and appropriate design solutions. 6.1 Determining Modal Priorities for Operations, Safety, and Comfort As discussed in Chapter 1, the built environment presents many challenges for the practitioner seeking to improve bicycle and pedestrian safety. For example, roadways which do not provide basic accommodations will require persons to walk or bicycle in the travel lanes with motor vehicles. As a result, their exposure is dramatically increased, along with their risk of being struck by a vehicle, particularly during periods of low light or darkness. When a roadway was not designed to accommodate pedestrians and bicyclists, it may be necessary to create space to install a countermeasure by applying one of the following strategies: • Removing or narrowing space dedicated to motor vehicles, such as travel lanes, turn lanes, or parking; • Reconstructing the existing right-of-way to reallocate space or add missing infrastructure (such as a sidewalk) within existing right-of-way; or • Expanding the existing right-of-way to create additional space. Where it is necessary to reduce space allocated to motor vehicle use to implement a bicycle facility, public support and decisions regarding modal priorities can further constrain countermeasure options. Chapter 5 provided a framework for filtering safety countermeasures based on project contexts and identifying an associated priority user or users. However, the act of selecting a priority user does not resolve intersection conflicts. Practitioners must assess the following three metrics to understand potential modal trade-offs when choosing countermeasures to improve intersection safety: • Operations. How can the intersection design minimize delay, or even improve the efficiency with which people move through the intersection, regardless of modal priority? • Safety. How can the intersection design reduce or eliminate exposure to conflict, and where conflicts may occur, how can the design reduce the potential risk of injury or death? • Comfort. How can the intersection design improve the experience and comfort of people moving through the intersection? Table 29 provides a relative qualitative assessment of each countermeasure’s potential effect on the operations, safety, and comfort of roadway users traveling by different modes. For the purposes of this table, it is assumed that transit passengers will experience the same effects as motorists. The comparison chart builds on information provided in the Countermeasure Glossary entries in the Appendix. When the effect is neither positive nor negative, no rating is provided, as indicated by “+ / −.” The table also provides relative costs, relative spatial impact of the countermeasure, and amount of public process typically required to implement the countermeasure. Note that this is a generalized table, therefore the impacts presented in the table may not hold true at every intersection under all project contexts. The table assumes that each countermeasure is deployed within in its applicable context. Practitioners can more specifically assess the influence of a specific countermeasure on a specific intersection user by employing analytical tools such as level of service (operations), level of traffic stress (user comfort), and crash modification factors (safety), as discussed in Chapter 3.

85 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Table 29. Design Trade-Offs of Safety Countermeasures Spatial Impact Estimated Cost Maintenance Cost Public Process Motorists Pedestrians Bicyclists Operations User Comfort Safety Operations User Comfort Safety Operations User Comfort Safety Active Warning Beacons Small $$ $$ 1 + / − + / − + / − + / − + + + / − + + Advance Stop/ Yield Lines Small $ $ 1 + / − + / − + + / − ++ ++ + / − ++ ++ All-Walk Phase Small $ $ 3 − − ++ ++ − − ++ ++ − − ++ ++ Bicycle Lane Extension Through Intersections Moderate $ $ 1 + / − + + / − + / − + / − + / − + / − + + Bicycle Signals Small $$ $$ 1 + / − + / − + / − + / − + / − + / − + / − ++ + Bike Boxes Moderate $$ $$ 1 − + + / − + / − ++ + + ++ + Continuous Raised Medians Moderate $$$ $$ 4 + / − + / − + − + ++ − + ++ or Hardened Centerlines Small $ $ 1 + / − + / − + − + ++ − + ++ Crossing Barriers Moderate $$ $$ 5 ++ ++ ++ − − − − ++ − − − − ++ Crossing Islands Moderate $$ $$ 3 + / − + / − + ++ ++ ++ ++ ++ ++ Curb Extensions Moderate $$ $$ 1 + / − ++ + / − ++ ++ + ++ ++ + Curb Radius Reduction Moderate $$ $$ 1 − − − + ++ ++ ++ ++ ++ ++ Gateway Treatments Small $ $ 1 + / − − + / − + + ++ + + ++ Grade-Separated Crossings Large $$$$ $$$$ 5 + / − ++ ++ − − − − ++ − − − − ++ High-Visibility Crosswalk Markings Small $ $ 1 + / − + + / − + + + + + + In-Street Pedestrian Crossing Signs Small $ $ 1 + / − − + / − + + + + + + Leading Bicycle Interval Small $$ $$ 1 − + + / − + + + + + + Leading Pedestrian Interval Small $ $ 1 − + + / − + ++ + + ++ + Lighting Small $$ $$ 4 + + ++ + + ++ + + ++

86 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Spatial Impact Estimated Cost Maintenance Cost Public Process Motorists Pedestrians Bicyclists Operations User Comfort Safety Operations User Comfort Safety Operations User Comfort Safety Mini-Traffic Circles Large $$ $$ 4 − − + − − + − − + / − Mixing Zone Treatments Moderate $$ $$ 3 + + / − + / − + / − + / − + / − + / − − + No-Turn-on-Red Signs Small $ $ 1 − − + / − ++ ++ ++ ++ ++ ++ ++ Parking Restrictions at Crossing Locations/ Daylighting Moderate $ $ 2 + / − + ++ + + ++ + + ++ Passive Bicycle Signal Detection Small $$ $$ 1 + / − + / − + / − + / − + / − + / − ++ ++ + Pedestrian Countdown Signals Small $$ $$ 1 + / − + / − + / − + ++ ++ + ++ ++ Pedestrian Hybrid Beacon Small $$$ $$$ 4 − + + + ++ ++ + ++ ++ Protected Intersections Large $$$$ $$$$ 3 − ++ + + ++ ++ ++ ++ ++ Protected Phases Small $ $ 4 − − ++ + − − ++ ++ − − ++ ++ Raised Crossings Moderate $$ $$ 3 − − + ++ ++ ++ ++ ++ ++ Rectangular Rapid Flashing Beacon Small $$ $$ 1 + / − + / − + / − + / − + + + + + Road Diet/ Rechannelization Large $$ $$ 5 − + / − ++ ++ ++ ++ ++ ++ ++ Roundabouts Large $$$$ $$$$ 5 + + + + + + − + / − + − + / − Signal Timing Small $ $ 3 + / − + / − + + + + + + + Traffic Signals Small $$$$ $$$$ 3 + / − + + / − + / − + + / − + / − + + / − Two-Stage Bicycle Turn Queue Boxes Small $ $ 1 + / − + + / − + / − + + / − + / − + + / − KEY ++ very positive benefit + positive benefit + / − neutral − disbenefit − − strong disbenefit Relative Cost $ = <2,500 $$ = 2,500–49,999 $$$ = 50,000–150,000 $$$$ = >150,000 Public Process 1. No public process, engineering decision 2. Public notice, engineering decision 3. Minimal public process, engineering decision 4. Moderate public process needed to build partner agency and community support 5. Extensive public process needed to build community and political support

87 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Following this initial assessment, some potential countermeasures may drop from consideration, because they provide insufficient benefit for the priority user, or because the impact to a particular mode in the applicable context is too great based on the agency’s policies, goals, or standards. Additional criteria typically need to be applied to narrow down the options to a preferred treatment. As highlighted in Chapter 1, these considerations can derive as much from political forces as from engineering or planning goals, and include the following factors: • Crash history. The number, severity, and type of crashes occurring at an intersection can create a strong, specific case for prioritizing certain intersection designs. Practitioners can also use crash history when prioritizing design efforts across multiple intersections. In addition to analyzing actual crashes, practitioners can use data on avoidance maneuvers and near misses, when available, along with measures of bicycle and pedestrian comfort to understand the potential effects of a particular safety treatment, as described in Chapters 2 and 3. • Benefit-to-cost ratio. Benefit–cost analyses can help practitioners identify and prioritize treatments based on level of risk of injury or death or other factors determined to be important to the community. Section 6.3 lists specific factors to consider when assessing benefits and costs, and references more-detailed sources on the topic of performing benefit–cost analyses. • Modal plans. Plan and policy documents such as comprehensive plans, land development regulations, and vision plans point to the intersection’s desired transportation and land use contexts. Understanding how the range of applicable intersection countermeasures align or conflict with these contexts can guide practitioners to countermeasures that are supported by the community’s vision, as expressed in these documents. If the stated transportation and land use goals are high level or unclear, interviews with key stakeholders (e.g., decision-makers, local advocacy groups) can help practitioners better understand the local vision(s) for the intersection and its surroundings. • Local, regional, and federal funding availability. As discussed in Chapter 1, design plans move from concept to implementation only after funding becomes available. The amount and availability of potential funding can influence whether the treatment selection process focuses on low- cost, systemic safety treatments, or higher-cost capital improvements tailored to individual intersections. Funding can come from a range of sources, and it is important to understand where, when, and how relevant funding sources can be accessed. This information also influences the decision-making process by determining which agency department is pursuing the funding and whether a safety project can be advanced in the near-, mid-, or long-term. Agencies can plan project implementation timelines around funding application deadlines and pursue phased implementation or prioritize “low-hanging fruit” safety countermeasures that have readily available funding or can be piggybacked onto a larger funded project. At the same time, agencies can develop thoughtful, long-term plans for implementing safety countermeasures that may require more substantial, dedicated funding sources. • Public interest and involvement. Community support for, or opposition to, specific modes or treatment types can also influence the design process. Unlike the previous considerations that are more readily quantified, a thoughtful public involvement process is useful for obtaining more- qualitative community input (see Figure 40). A well-designed public process should ensure full representation of perspectives and be used as a tool to build consensus and solve safety challenges. Conversations with members of the public who regularly use the intersection(s) can shed light on challenges to bicycle and pedestrian safety and comfort that may not be apparent from an analysis of the available data. Discussing multiple alternatives in a public forum can inform the selection of an alternative that aligns well with public desires while meeting key project safety outcomes. Incorporating input from focus groups with members of the community and key stakeholders can also help build community consensus. Note that safety countermeasures which Assessing Trade-Offs: Assuming pedestrians and bicyclists benefit from both scenarios, which investment would you choose? • Alternative A meets 100% of the intersection needs, but costs $$$$ • Alternative B meets 80% of the intersection needs, but costs $$

88 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Figure 40. Stakeholders gather for a field visit to better understand opportunities and constraints along a transit corridor in Orlando, Florida. Source: Kittelson & Associates, Inc. do not require changes to parking, travel lanes, or traffic operations, or require the purchase of additional land can often be implemented without an extensive public process and can be installed based on engineering judgment or study (e.g., reducing lane widths, installing signs, modifying curb radii, installing curb extensions, modifying signal timing). Countermeasures that need a public process (e.g., road diet) benefit from a proactive, robust public involvement process by raising public awareness of the potential project well before a final decision is made and by allowing public input to influence the ultimate treatment selection and design. The public involvement component of the planning process can also be a venue for community leaders to take ownership of the project, and champion the design through implementation. FHWA’s Guidance on Public Involvement suggests techniques for conducting effective public involvement processes. 6.2 Limitations in Local, Regional, or State Policy Identifying viable intersection countermeasure options can require practitioners to understand local, regional, and federal policies that govern design. In some instances, a policy may restrict the use of a countermeasure or limit its effectiveness (e.g., prohibitions from using raised crosswalks, or standards mandating minimum lane widths or curb radii at intersections). An understanding of these policies and standards is important, as is an understanding of the flexibility available in guidance that can be critical to the practitioner’s ability to use a countermeasure or deploy it to its maximum safety potential. Transportation Standards A range of local, state, and federal transportation standards can constrain otherwise-viable intersection designs. The intersection assessment process must account for these standards, which can include minimum operational performance and minimum design requirements, among others. The applicable standards may vary by state, jurisdiction, and facility owner, with the result that adjacent intersections may be subject to different standards if they are controlled by different transportation agencies. Practitioners should generally consider the following types and sources of standards: • Operational standards. Transportation agencies may set minimum standards for roadway operational performance, as measured by motor vehicle level of service, volume-to-capacity ratio, queue length, vehicle-miles traveled, or other performance measures. Intersection countermeasures that cause operational performance to fall below the minimum standard may be difficult to implement unless exceptions are made or other priorities are elevated.

89 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS • Manual on Uniform Traffic Control Devices. The MUTCD is a federal document regulating the design and use of traffic control devices such as pavement markings (e.g., crosswalks), signs, and signals. Many states maintain a state- specific supplement to the MUTCD identifying, among other things, design options allowed in the federal manual but not allowed in that specific state. All intersection designs must comply with MUTCD guidelines to qualify for federal or state funding. Promising countermeasures that are not permitted by the current MUTCD may be proposed by a jurisdiction to FHWA as an experiment. If FHWA accepts the experiment, and if a follow-up study can document the effectiveness of the treatment, FHWA may issue an interim approval for the treatment that will allow other jurisdictions to use it, with notice to FHWA. MUTCD Section 1A.10 describes the steps involved in the experimentation process. • American Association of State Highway and Transportation Officials policies and guidebooks. AASHTO maintains a variety of guidebooks on intersection design. The Guide for the Development of Bicycle Facilities (2019) contains guidance on addressing a range of bicycle design issues at intersections. The Guide for the Planning, Design, and Operation of Pedestrian Facilities (2004) provides guidance on the planning, design, and operation of pedestrian facilities along streets and highways. AASHTO’s Policy for Geometric Design of Highways and Streets (Green Book) provides a foundation for intersection design. The Green Book, in particular, is frequently referenced in agency roadway design standards. Finally, the HSM provides procedures for forecasting the safety effects of different design alternatives, although most of the content in the first edition focuses on motor vehicle safety. When agency standards reference an AASHTO publication, a design exception (if the agency’s process allows for it) would be required to go outside the standard. The guidebooks published by the National Association of City Transportation Officials (NACTO), a professional association of major North American cities and transit agencies, offer innovative solutions for addressing transportation issues and multimodal safety in urban areas. Two examples are the Urban Bikeway Design Guide and the Urban Street Design Guide. The descriptions of the design concepts featured in these guides provide information on whether the concepts comply with common national standards, or whether design exceptions or MUTCD experimentation requests would be necessary to implement them. Flexibility in Policies Existing policies and standards can encourage a rigid, formulaic decision-making process and reduce the probability that context will be adequately considered in addressing the identified safety problem. Practitioners should recognize where existing policies may unnecessarily limit an agency’s flexibility to implement multimodal design solutions and assess whether those policies are being misinterpreted or are in need of revision. In many cases, the most-effective solution requires moving away from traditional auto-centric intersection standards, while still considering the needs of all intersection users and prioritizing safety. FHWA has expressed its support for using the flexibility generally available in existing guidance to address bicycle and pedestrian safety issues [Bicycle and Pedestrian Facility Design Flexibility (Shepherd et al. 2013)] and maximize the use of limited right-of- way. FHWA has also provided guidance that highlights ways that practitioners can apply design flexibility to address common roadway design challenges and barriers (FHWA 2016a). These national documents emphasize the importance of increasing awareness of the flexibility which exists in existing guidance to solve intersection safety issues. Design Spotlight: Flexible Design Standards in San Francisco, CA In 2016, the city of San Francisco removed automobile delay as a measure to assess the environmental impact of new developments. The city replaced automobile level of service (LOS) with a measure of vehicle-miles traveled (VMT) to understand the impact of development and transportation projects. By focusing on VMT, developers are rewarded for building infill projects closer to other destinations. This is in sharp contrast to LOS, which discourages development in already congested areas of the city.

90 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS When design flexibility is needed to effectively implement a priority intersection safety treatment, practitioners should apply the three key elements of a flexible design approach: engineering judgment, documentation, and experimentation. • Engineering judgment involves the professional analysis of relevant data, and the application of appropriate principles and techniques to solve engineering challenges. Engineering judgment should be applied by a knowledgeable professional. Professionals may use the principles and decisions referenced in design manuals to inform engineering solutions, but these resources should be calibrated to match local context and conditions. • The thoughtful documentation of design decisions through memoranda, engineering studies, and other methods can capture the analysis and reasoning behind a design solution and build a case for applying flexibility or deviating from existing guidance. The process of documenting design decisions is typically a key part of design exception processes. Documentation also provides an important backup in case of litigation and can minimize an agency’s exposure. • Experimentation helps drive the advancement of the design practice and the adoption of new intersection design strategies. Experimenting with newer designs can expand the designers’ toolbox by providing the data necessary to show the effectiveness of new designs. Performance-Based Street Design Incorporating a performance-based design approach into the street design process enables practitioners to make informed decisions regarding performance trade-offs. This approach has been applied to bicycle, pedestrian, and safety projects in states and communities across the country, and is especially helpful when developing solutions in fiscally and physically constrained environments. National activities and associated publications, such as FHWA’s Performance-Based Practical Design initiatives and NCHRP Report 785: Performance-Based Analysis of Geometric Design of Highways and Streets, have resulted in a framework for how this approach can be executed within a design project (Ray et al. 2014). Clear documentation of a performance-based approach can encourage effective problem-solving and collaborative decision-making, and provide an overall greater return on infrastructure investments. Performance-based design is broadly a three-phased process consisting of: (1) project initiation, (2) concept development, and (3) evaluation and selection. This approach requires designers to consider and select design values or features based on their impact, role, and relationship to the resultant roadway design performance. It is key to understand the difference between design values that meet a nominal safety design and those that produce a substantive safety benefit; unfortunately, nominal safety does not always lead to substantive safety (see Chapter 1). At the project initiation stage of Design Spotlight: Private Development as a Route to Safe Multimodal Design • The development review process provides transportation agencies with regular opportunities to commission multimodal operational analyses and invest in intersection infrastructure. • Local policy governs what gets studied and which problems get solved. The problems and resulting solutions are subject to local politics and preferences. • If jurisdictions seek to promote multimodal activity or nonmotorized user priority in particular locations, they can capitalize on development interests to assess how future development and design could improve multimodal access at project intersections. • Multimodal design elements may be offered by project applicants as part of the development review and approval process, providing jurisdictions with another way to implement multimodal treatments.

91 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS the process, it is desirable to consider the following performance-based considerations to improve safety for pedestrians and bicyclists: • The vulnerability of the pedestrians and bicyclists compared to the motorists • The system impact of improvements to expand a bicycle or pedestrian network • The impact of comfort on the choice of a person to walk or bicycle (e.g., provision of physical separation between motorists and people walking or bicycling, the size of refuge islands) • The impact of motorist comfort operating in potential conflict with, or close proximity to, vulnerable users (e.g., shared lanes versus bicycle lanes, protected phasing versus permissive phasing) • Exposure of vulnerable users to potential conflict (e.g., the length of street crossings) • The relative comfort and operational impact of the crossing design for pedestrians and bicyclists (e.g., a one-stage crossing versus a three-stage crossing) • Equity of resources and comparative provision of infrastructure between modes Figure 41 illustrates a context that clearly did not consider the criteria above. The use of a performance-based street design process would have considered the inequity associated with the lack of any provisions for walking or bicycling and the relative challenge of maintaining preferred motor vehicle lane geometry and LOS standards while striving to retrofit missing pedestrian and bicycle infrastructure. In contrast, the example highlighted in Figure 42 shows a roadway that was designed using a performance- based design framework. 6.3 Assessing Benefits and Costs Benefit–cost analyses assess whether (and by how much) the positive project outcomes (e.g., lives saved, serious injuries reduced, network connectivity improved, delay avoided) outweigh the project- related costs (e.g., construction costs, maintenance costs, increased property damage, increased fuel consumption). These analyses involve data collection, the thoughtful assessment and selection of assumptions, and the accurate conversion of all cost and benefit elements to a consistent, readily understandable unit (often dollars). Practitioners must consider a wide range of benefits and costs accrued by different intersection designs and safety treatments. The following subsections outline various costs and benefits that practitioners should consider when assessing the potential effectiveness of proposed safety countermeasures. Figure 41. Roadway designed without sufficient consideration of impacts to vulnerable user safety, comfort, or convenience. Source: Toole Design

92 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Nickerson Street: Applying Performance-Based Street Design in Washington The Seattle Department of Transportation (SDOT) used performance-based street design principles to implement the first of many strategic road diets, or “rechannelizations,” on the Nickerson Street corridor in the city’s Queen Anne neighborhood. Prior to 2010, Nickerson Street was a four-lane roadway serving a mix of land uses, including retail shops, restaurants, multifamily homes, and the Seattle Pacific University Campus. The corridor posed several safety challenges: the wide roadway cross-section and lack of crosswalks made it difficult for pedestrians to cross, and most drivers exceeded the corridor’s 30-mph speed limit. To make matters worse, SDOT was compelled to remove three crosswalks from the corridor because they no longer complied with guidelines for when to use uncontrolled crosswalks (i.e., the roadway was too wide to safely accommodate uncontrolled crosswalks). SDOT identified a series of performance measures before implementing countermeasures to improve pedestrian safety and increase driver compliance with the speed limit. The agency gathered data on traffic volume, vehicle speeds, and crashes before the rechannelization project. In 2010, SDOT restriped the roadway to one lane in each direction with a center two-way left-turn lane and bicycle lanes (see Figure 41). After reducing the number of travel lanes, the agency reintroduced uncontrolled marked crosswalks into the roadway and installed median islands. Reducing the roadway width to one lane in either direction also decreased the risk of shielding crashes, where a vehicle in the outer travel lane yields to the pedestrian while the vehicle in the inner travel lane does not yield. By taking a performance-based approach and gathering metrics based on traffic volume, vehicle speeds, and crash history, SDOT was able to quantify the positive results of the rechannelization. The agency collected data on each metric after the rechannelization and showed that the project resulted in a 23-percent reduction in collisions, more than a 90-percent drop in top-end speeders, and a 1-percent decrease in traffic volumes. The success of the Nickerson Street project supported future SDOT efforts to rechannelize other wide Seattle streets. As of March 2012, 36 road rechannelizations had occurred in the city. Aggressive speeding and crashes resulting in injuries also decreased on these corridors, while traffic volumes generally remained stable. By using performance-based design principles, SDOT leveraged a corridor-specific project into a systemic safety treatment that benefits pedestrians and bicyclists citywide. Figure 42. Multimodal safety improvements on Nickerson Street in Seattle were implemented as part of a performance-based practical design process. Source: Google Earth

93 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS Costs NCHRP Web-Only Document 220: Estimating the Life-Cycle Cost of Intersection Designs (Rodegerdts et al. 2015), provides greater detail on many of the data inputs and processes needed to estimate project costs. Unless otherwise noted, all suggested costs in this section reflect the information in NCHRP Web-Only Document 220. • Capital. Costs associated with constructing the intersection treatment. These include project development, engineering, right-of-way, construction, and utility costs associated with the project. • Operations and Maintenance. Costs associated with maintaining the intersection treatment over time. • Environmental (Emissions). Costs associated with emissions released based on vehicle volumes or idling at the intersection without a net offset via shifts to other modes. The cost of greenhouse gases is monetized using the method outlined in the Social Cost of Carbon for Regulatory Impact Analysis by the Interagency Working Group on the Social Cost of Carbon. • Safety. Costs associated with the number and severity of safety conflicts and crashes. Fatal crashes are monetized using the Value of a Statistical Life (VSL), which is provided by the DOT, and crashes with nonfatal injuries are monetized using a fraction of the VSL for their assorted severity level (i.e., a severe injury would have a higher VSL than a complaint-of-pain injury). NHTSA provides a recommended monetized value for each vehicle involved in a property damage-only (PDO) crash. Even with this differentiation noted, it is important to remember that a safety cost–benefit analysis should focus on reducing serious and fatal injuries, and not just an assessment of total crashes. For example, some countermeasures may improve overall safety by reducing serious injuries and fatalities, even though they may increase PDO crashes (e.g., roundabouts). • Congestion. Costs associated with net increased user delay (i.e., after accounting for delay for pedestrians and bicyclists) at the intersection. U.S. DOT guidance and the AASHTO Red Book (AASHTO 2010b) relate users’ value of time to their wage rate to monetize user delay. Different fractions of a users’ wage rates are assigned to users based on transportation mode and trip purpose. However, care should be taken to not give disproportionate weight to the aggregate “benefits” of minor reductions in congestion to platoons or groups of people over individual users. For example, while an intersection may result in 5 seconds of average delay reduction to thousands of motorists, the realized gain of time is 5 seconds for each individual motorist. If this comes at a cost of 30 seconds or more of delay to crossing pedestrians or bicyclists, the impact is quite disproportionate and may discourage walking or bicycling or increase the likelihood of risky crossing behaviors. • Reliability. Costs associated with decreased travel time reliability through the intersection. If reliability data are available, value-of-time data for intersection users can be used to monetize travel time reliability. The Strategic Highway Research Program (SHRP) 2 Project L17 describes several approaches to valuing reliability. • Access and Equity. Costs associated with missing or inadequate multimodal access through the intersection. An assessment of latent demand (the number of nonmotorized users likely to use an intersection if safe and comfortable facilities were available), combined with costs associated with increased travel time (on an alternate route instead of through the intersection) can be used to monetize accessibility. Researchers have applied a simplified four-step travel demand model for four trip purposes (school, shopping/restaurants, parks, walk to transit) to estimate latent demand (Reardon et al. 2017). For example, a decision to require a pedestrian to cross at an intersection located 300 feet or more away from the desired location, or to require a three-stage crossing so that intersection capacity The high cost of crashes in America • In 2014, the price tag for crashes resulted in $871 billion in economic loss and societal harm, with economic costs alone amounting to nearly $900 for each person living in the United States (NHTSA, 2014). • In 2015, the comprehensive cost of crashes ranged from $47,000 for PDO crashes to $10 million per person for fatal crashes. Comprehensive costs include the economic cost and a measure of the value of lost quality of life (obtained through empirical studies of what people actually pay to reduce their safety and health risks). • On average, 13 American people were struck and killed by a car while walking every day between 2008 and 2017 (Smart Growth America 2019).

94 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS for motorists is maximized, disproportionately limits pedestrian access and can have serious impacts on mobility-challenged people (see Figure 43). • Economic. Costs associated with blighted economic activity in the vicinity of the intersection. Since effects on businesses vary by location, agencies should accumulate localized economic data (e.g., sales, employees) to help estimate the effects of projects on businesses. • Health. Costs associated with fewer people walking, biking, using transit, or otherwise exercising (e.g., increases in obesity, heart disease, and related medical costs). The Centers for Disease Control and Prevention and its partners have developed estimates of the percent of health care expenditures associated with inadequate levels of physical activity (Carlson et al. 2014). • Housing and Transportation. Costs associated with raised property values or the use of more- expensive forms of transportation (e.g., auto- centric travel). The Center for Neighborhood Technology provides the average combined cost of housing and transportation for U.S. metropolitan and micropolitan areas. Costs can be assessed from the regional to the neighborhood level (Center for Neighborhood Technology 2018). Benefits NCHRP Web-Only Document 220: Estimating the Life-Cycle Cost of Intersection Design (Rodegerdts et al. 2015) also provides greater detail on many of the data inputs and processes needed to estimate project benefits. Depending on the selected intersection treatment and the specifics of the location, many potential costs can become benefits. Preliminary approaches to monetizing the following benefits can be found in the Costs subsection above. • Environmental (Emissions). Benefits associated with reduced emissions based on a net reduction in vehicle volumes or Figure 43. Intersection that has clearly prioritized motorist convenience over pedestrian safety and convenience. Source: Google Earth

95 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS idling at the intersection (e.g., through accommodating more trips via other modes). • Safety. Benefits associated with reductions in safety conflicts and crashes. • Congestion. Benefits associated with net decreased user delay (including pedestrians and bicyclists) at the intersection. • Reliability. Benefits associated with increased travel time reliability through the intersection. • Access and Equity. Benefits associated with increasing multimodal access through the intersection. • Economic. Benefits associated with increased economic activity in the vicinity of the intersection. • Health. Benefits associated with more people walking, biking, using transit, or otherwise exercising (e.g., decreases in obesity, heart disease, and related medical costs). • Housing and Transportation. Benefits associated with stable property values or the use of less-expensive forms of transportation (e.g., transit, nonmotorized transportation). Conducting Cost–Benefit Analyses at Intersections Many tools and resources exist to help practitioners design and conduct cost–benefit analyses on intersection safety treatments. NCHRP Web-Only Document 220: Estimating the Life-Cycle Cost of Intersection Designs, and FHWA’s Safety Performance Intersection Control Evaluation (SPICE) tool both provide practice-ready tools for conducting cost–benefit analyses. Other useful tools include the Pedestrian and Bicycle Information Center’s Pedestrian and Bicycle Countermeasure Cost Report and Pedestrian Crash Modification Factors Toolbox. 6.4 A Process to Identify Flexible Solutions Every transportation agency has its own design process, which generally involves three stages: • Project initiation, • Preliminary design, and • Final design. Revisit Safety Issues and Intended Project Outcomes Performance Categories (Chapter 2–4) Identify and Refine Countermeasures (Chapter 5–6) Select Safety Project Evaluate Performance Outcomes and Access Financial Feasibility Finalize Countermeasures Based on Performance Figure 44.  Performance-based selection of safety countermeasures.

96 GUIDANCE TO IMPROVE PEDESTRIAN AND BICYCLIST SAFETY AT INTERSECTIONS The preliminary design phase provides a vital opportunity for practitioners to weigh the design trade-offs of potential intersection treatments, assess the benefits and costs of each option, and select the intersection design that best aligns with the transportation and land use contexts and supports operations, safety, and comfort for all intersection users. The task of establishing and implementing a design process that encourages the consideration and assessment of flexible design solutions ultimately falls on individual transportation agencies. Federal guidance on developing a flexible, performance-based process framework for intersection design can be found in NCHRP Report 785: Performance-Based Analysis of Geometric Design of Highways and Streets. Figure 44 presents a sample performance-based process framework that builds on the process outline in NCHRP Report 785 but is tailored to implementing bicycle and pedestrian safety countermeasures at intersections. It is also important to take a step back and understand the intersection design process within the broader context of identifying and implementing effective safety countermeasures at intersections. As a reminder, the following process was described and depicted at the beginning of this Guide as a way for practitioners to identify appropriate safety treatments (see Figure 45). It is hoped that this process, accompanied by the guidance and information in each chapter, will lead practitioners to the appropriate countermeasures or package of countermeasures to address identified safety concerns and work to improve pedestrian and bicyclist safety at intersections. Chapter 7 provides important information about evaluation as an epilogue to the countermeasure selection process. Figure 45. Countermeasure selection process. Identify Treatment Options for Creating Safer Intersections Countermeasure Options Final Countermeasure Selection Evaluate Priorities and Assess Trade-Offs and Viability 4566 Frame the Process Analyze Intersection Safety and Identify Issues Identify and Collect the Data for Analysis 1 2 3Chapter Chapter Chapter Chapter Chapter Chapter Chapter Refine the

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Intersections are challenging locations for all road users, but they can be especially difficult for people walking and biking. Between 2014 and 2016, 27 percent of pedestrians and 38 percent of bicyclists killed in crashes were struck at intersections.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 926: Guidance to Improve Pedestrian and Bicyclist Safety at Intersections provides a succinct process for selecting intersection designs and operational treatments that provide safety benefits for pedestrians and bicyclists, and the most appropriate situation for their application.

In 2016 and 2017, pedestrians and bicyclists made up 18 percent of all fatalities on U.S. streets, despite representing less than 4 percent of all trips. This continues an upward trend in these modes’ share of roadway fatalities since 2007.

An erratum was issued for this report: Tables 15 through 24 have been updated to match the summary Table 25 in the online version of the report.

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