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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
×
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
×
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
×
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Suggested Citation:"Chapter 2 - Pedestrians." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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2-1 Pedestrians should be expected at most A.I.I.s., and the design should integrate their needs, starting at an early concept development stage and continuing throughout the design process. Pedestrians are vulnerable road users; their risk of death in a crash increases significantly with higher vehicle speed (2). The design of A.I.I.s should provide for people walking, with con- sideration of pedestrians of all abilities. The Americans with Disabilities Act (1) specifies that if pedestrian facilities are provided, they must serve the need of all pedestrians, including those with disabilities. Understanding the needs and characteristics of the full range of pedestrians is a critical component of developing inclusive designs. 2.1 Characteristics of Pedestrians Design parameters and guidance are set forth by FHWA, AASHTO, the U.S. Access Board, and other entities to construct sidewalks and other pedestrian facilities that serve pedestrians (e.g., 1, 3, 4, 5, 6). Designers should recognize that people have a wide range of physical, cogni- tive, and sensory abilities, meaning roadway design should serve the variety of pedestrians that might be present and the different characteristics of those pedestrians. Young adults typically walk at a faster pace than older adults do. Children, young teens, people with disabilities, and elderly individuals may have limitations in their ability to predict the speed of oncoming traffic and detect gaps. Designers should identify all likely users and ensure that all designs meet the needs of these users. 2.1.1 Walking Speeds Most pedestrians walk at speeds between 2.5 ft/s and 6.0 ft/s. A design speed of 3.5 ft/s is typical for calculating signal timing and similar design parameters (3). In some locations with higher populations of young children, older adults, people with disabilities, and/or large groups of people walking together, walking design speeds of 3.0 ft/s or lower may be more appropriate (2, 3). FHWA notes that speeds can be higher or lower than these ranges, citing that 15% of older pedestrians were more comfortable at a lower speed of 2.2 ft/s (7). Depending on local context (e.g., proximity to schools or hospitals), designers may use values that are lower than the 3.0 ft/s noted above. 2.1.2 Spatial Needs For two people walking side by side or passing each other while traveling in opposite direc- tions, the average space taken up is 4.67 feet (2). Wheelchair users typically need at least 5 feet of width to pass each other, and 5.4 feet is appropriate for a walking pedestrian to pass a C H A P T E R 2 Pedestrians

2-2 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges person pushing a double stroller. Greater sidewalk widths are needed as volumes of pedestri- ans increase, and pedestrian facilities in urban areas tend to require more space than in lower volume areas. Where vertical objects are present (e.g., building faces, bridge parapets, sign- posts), pedestrians tend to shy away from these objects to provide space between themselves and the object. This shy distance, which is typically 1 foot or greater, reduces the effective width of pedestrian facilities. Shy distance from vertical surfaces is generally not included in the cal- culation of pedestrian space (8), nor is pedestrian space that may be affected by opening doors from cars or buildings. 2.1.3 People with Disabilities Pedestrians with disabilities, including wheelchair users and pedestrians with vision impair- ments (e.g., those who are blind), are key design users. According to the 2010 Census, 56.7 mil- lion people (18%) in the United States and 52% of Americans age 65 and over reported having a disability. With the aging of the population, these proportions are expected to increase, and designs to serve these users should be a key focus. The range of different pedestrian disabilities has practical implications for the design of sidewalk widths, grades, cross slopes, refuge island widths, pushbutton placement, accessible signals, and curb ramps to comply with requirements set forth by the Americans with Disabilities Act (ADA). The regulations implemented with the ADA of 1990 (1) require newly constructed facilities to be “accessible to and usable by” individuals with disabilities [Sections 28 CFR 35.151(a)(1) and (b)(1)]. The Department of Justice published the 2010 ADA Standards for Accessible Design (9) to set minimum requirements for state and local government facilities, public accommoda- tions, and commercial facilities. These regulations addressed only some aspects of projects in the public rights-of-way. The proposed regulations for addressing public rights-of-way, Pro- posed Accessibility Guidelines for Pedestrian Facilities in the Public Right-of-Way [proposed Public Rights-of-Way Accessibility Guidelines (PROWAG)] was published in the Federal Register in 2011, but, as of this writing, has not been adopted as a final rule. However, the proposed PROWAG is recognized by FHWA (10) as the best practice for the design of ADA-compliant pedestrian facilities in public rights-of-way. The guidance of these proposed rules is generally considered minimum needs for access. A pedestrian access route within the sidewalk must be at least 4 feet wide, firm, stable, slip- resistant, and free of surface discontinuities, with no more than 2% cross slope (the slope perpendicular to the direction of travel). Passing spaces at least 5 feet wide are required every 200 feet. The proposed PROWAG allows sidewalk grade within the right-of-way to be the same as or less than the grade of the adjacent roadway. A maximum running grade of 5% is required for shared-use paths if constructed on a separate alignment from a roadway. Curb ramps must be provided where the sidewalk or shared-use path crosses a curb. The proposed PROWAG provides specifications for perpendicular curb ramps, parallel curb ramps, and blended transi- tions. Detectable warning surfaces (truncated domes) are required on curb ramps or blended transitions to alert blind pedestrians to the location of the street. The proposed PROWAG also requires accessible pedestrian signals (APS). The Manual on Uniform Traffic Control Devices (MUTCD) provides standards for APS that include audible and vibrotactile indications of the walk interval, pushbutton locator tones, tactile arrows, and auto- matic volume adjustment (3). Guidance is also provided to identify the specific location of APS devices associated with the crosswalks they serve. The proposed PROWAG contains other information on sign mounting height and legibility, maintenance of accessible features, and maintenance of the pedestrian access route during construction activities.

Pedestrians 2-3 When designing for people with disabilities, it is important to design not just for the minimum requirements, but with consideration for the needs of all other users of the facility and their rela- tive volumes. For example, while the minimum curb ramp width to meet accessibility require- ments is 48 inches in proposed PROWAG, that width cannot accommodate large groups of people walking or accommodate bicyclists operating on a shared-use path. Wider curb ramps may often be necessary or appropriate. 2.1.3.1 People with Mobility Disabilities People with mobility disabilities may include those using wheelchairs, scooters, support canes, crutches, walkers, and prostheses. For these users, surfaces need to be smooth, stable, and slip- resistant, and there should be adequate room to maneuver. Curb ramps are required where a pedestrian access route crosses a curb. Maximum running slopes for ramps, street crossings, and the sidewalk or shared-use path area are specified in ADA requirements. Cross slopes steeper than 2% along any point of the pedestrian access route can also be a significant problem for individuals using mobility aids when traveling on the sidewalk or negotiating curb ramps. Grates or cracks wide enough to catch the tip of a cane or the front casters of wheelchairs limit the usefulness of a facility. These features must be carefully considered in the design, construc- tion, and maintenance of crossings, refuge islands, and travel paths through all intersections, including A.I.I.s. 2.1.3.2 People with Vision Disabilities People with vision disabilities often travel independently and must walk or use transit during their travels. Many people who are blind or who have low vision use a white cane, dog guide, or other mobility aid; however, many who are legally blind may not use any aid that identifies them as blind. Elderly pedestrians with macular degeneration may not see details in a way that allows them to read signs, recognize faces, or see pedestrian signals, but may nonetheless travel without using any type of mobility aid. Warning surfaces, such as truncated dome detectable warnings, must be detectable underfoot, and with a white cane. Although a white cane or dog guide may be used to identify streets or obstacles in their paths, individuals who are blind or who have low vision use their hearing and other senses to maintain their orientation and travel efficiently to their destinations. These individuals will not already be oriented to each intersection location or area where they may travel. Just like sighted pedes- trians or drivers, they may get directions to a new location and travel there, figuring it out as they go. They may use accessible mapping or transit direction-type programs, if available, to gain information about their route, but details regarding signals or intersection configurations are usually determined by listening to traffic movement. Varying colors, materials, and textures are sometimes used in the sidewalk environment and, if used consistently, may provide useful information for individuals with vision disabilities. However, decorative changes in texture or pavement across a sidewalk may be mistaken for level changes by individuals with low vision, and the texture change may be confusing for a person who is blind. Individuals who use a white cane when traveling may use varying techniques in different settings. In outdoor travel on a sidewalk, the white cane is typically used in an arcing, tapping motion close to the sidewalk surface to detect changes in elevation or obstacles in the path. A small proportion of the population of individuals who are blind or who have low vision uses dog guides. Dog guides operate in response to commands from their handlers, who use voice commands, hand motions, or both. Handlers who are blind typically walk on the right side of the dog, and dog guides often walk near the left edge of the sidewalk. The dog guide stops to

2-4 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges indicate drop-offs (e.g., curbs or stairs) and waits for a command from the handler. Dog guides do not use traffic signals or decide about street crossings. They usually stay within the sidewalk area but can be confused by wide plaza areas or skewed crossings. More information about wayfinding and street crossing techniques is provided in Section 2.3. 2.1.3.3 People with Cognitive Disabilities Cognitive disabilities can hinder the ability to perceive, recognize, understand, interpret, and respond to information. The skills of people with cognitive disabilities vary widely, but they may have difficulty navigating intersections with complex configurations, signals, and signs. Designs that accommodate individuals with cognitive disabilities may also benefit adults who do not read English. Signs that use pictures, universal symbols, and colors can convey meaning to a range of individuals, but the symbols and colors should be consistent to improve comprehension. 2.1.3.4 People with Hearing Disabilities Hearing loss may limit pedestrians’ ability to use cues, such as the sound of approaching vehicles. This condition can be exacerbated where there are limited sight lines or complicated traffic patterns. It is unclear how this complication may affect the ability to recognize and detect traffic in conditions where traffic patterns are atypical. Providing additional visual cues and designing the angle at which a pedestrian crossing intersects traffic close to 90 degrees may help mitigate the absence of expected auditory cues. 2.1.4 The Walking Experience The experience of an A.I.I. for people walking will vary depending on the intersection. In some A.I.I. designs, a pedestrian may not perceive significant differences when crossing compared to doing so at a “traditional” intersection. In more complex intersection designs, the intersection may present subtle differences or more complex challenges to creating a safe and comfortable pedestrian experience, and these challenges should be anticipated and mitigated through design. For any A.I.I. design, there will be challenges to overcome in design, and opportunities to optimize the safety and operations for pedestrians through the intersections, as discussed in Chapter 1. Sometimes, the pedestrian experience through an A.I.I. can be safer and better opera- tionally than a traditional intersection for some movements. This guidebook is structured to help the reader recognize the challenges associated with designing for pedestrians in A.I.I.s and how these challenges may be addressed. The AASHTO Guide for the Planning, Design, and Operation of Pedestrian Facilities (2) assesses the decision to walk and the associated experience according to these key factors: • Distance and densities. The length of a trip greatly influences the decision to walk. Most walking trips are 1 mile or less, and community structures with higher densities of destina- tions and mixed land uses encourage walking trips. The design of A.I.I.s should include pedestrian design features in nearly any land use context. For A.I.I.s in areas with destinations near together and distributed on more than one quadrant of the intersection, the likelihood of people walking within the A.I.I. could be common and should be anticipated. • Route directness. Depending on the A.I.I., the pedestrian route through the intersection may not be as direct as in traditional intersections. Pedestrians value the directness of a walking route and are discouraged when forced to travel circuitous paths that take them out of their way. Where A.I.I.s require pedestrian routing that is indirect or nonintuitive, the designer should minimize the distance that pedestrians must divert from a direct path between points.

Pedestrians 2-5 • Personal safety and security. Many elements that the AASHTO Pedestrian Guide (1) notes as detrimental to a pedestrian’s sense of personal safety and security may be present at A.I.I.s, as with any intersection. Such elements include fast-turning motorists, long crossing dis- tances, and long block lengths. Some of these factors can be mitigated in A.I.I.s through atten- tive design, including constructing raised median refuges and implementing prohibitions against motorist turns across the crosswalk during the Walk interval. Other treatments that can enhance personal safety and security in A.I.I.s include pedestrian-scale lighting, railings, wider walkways, and increased separation or using physical barriers to motor vehicle traffic. Designs that improve personal safety and security can promote walking and bicycling activity throughout the day. • Personal comfort and attractiveness. Pedestrians are naturally more engaged with their surroundings than motorists are because pedestrians are moving more slowly through the roadway environment. Within an A.I.I., the presence of shade, artistic or visually interesting design treatments, and separation from motor vehicle traffic can all enhance the comfort and appeal of walking. Besides the aspects identified by AASHTO, travel time is an important factor in pedestrian activity. Travel time is the time to traverse the intersection, accounting for the length of the pedestrian route and walking speed, and delays incurred along the route. These delays may be created by multistage crossings, long cycle lengths at signalized locations, insufficient traffic gaps, or failure of motorists to yield at uncontrolled crossings. Pedestrian travel time through intersections and between destinations should account for the time in motion and the delay when stopped. 2.1.5 Safety Pedestrian safety can generally be viewed considering three tasks that must be completed by a pedestrian: traversing, wayfinding, and crossing as shown in Exhibit 2-1. These are described in the following sections. All three tasks can cause safety concerns, and all three can be mitigated through proper design techniques and using countermeasures, as needed. One of the key factors in pedestrian safety is vehicular travel speed, with higher speeds linked to a higher risk of injury or death to pedestrians if a collision occurs (2). Research has further shown that motorist yielding behavior at uncontrolled crossings declines with higher speeds Exhibit 2-1. Three components of pedestrian travel at A.I.I.s.

2-6 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges and multiple lanes of traffic (Exhibit 2-2) (11, 12). The overall design of the A.I.I. should con- sider alignments to maximize the comfort of nonmotorized users by creating a geometry that • Eliminates multiple-threat conditions; • Minimizes the need for uncontrolled movements across crosswalks and bicyclist crossings, particularly in high-speed and/or high-volume conditions; • Reduces motorist speeds at uncontrolled crossings; and • Provides lateral space between travel lanes and nonmotorized facilities by establishing buffer zones and/or widening sidewalks and sidepaths. Pedestrian safety is particularly important in nighttime conditions when visibility is limited. In 2017, the National Highway Traffic Safety Administration (NHTSA) reported that 74% of all pedestrian fatalities happened at night (13). Proper lighting of the overall A.I.I., with supplemen- tal lighting at any crossing point, is needed to enhance pedestrian visibility to drivers. An important design factor for street crossings is providing sufficient sight distance for pedes- trians and motorists to view each other clearly on the approaches to any conflict points. Both parties should be able to perceive and react to a potential conflict, and motorists should be able to come to a full stop before conflicting with a pedestrian. This sight distance, which is needed at both uncontrolled and controlled crossings and relates to multiple-threat conditions, is dis- cussed in Chapter 5. The design should provide adequate approach clear space before crossings Exhibit 2-2. Motorist yielding behavior at uncontrolled crossings. Source: (11, 12).

Pedestrians 2-7 by eliminating tall and opaque roadside elements that could limit visibility between motorists and vulnerable users approaching the crossing. At uncontrolled crossings, the ability to identify appropriate gaps in traffic is critical for pedes- trians. At controlled crossings, sight distance is critical when there are potential conflicts, such as permissive right-turns-on-red and concurrent pedestrian and motorist signal phases that could lead to turning conflicts with pedestrians. 2.2 Traversing When designing for pedestrians within an intersection, the designer should seek configu- rations that minimize out-of-direction travel and the number of crossings to be traversed in balance with the many other objectives the intersection form seeks to address. Large, complex intersections are often perceived by pedestrians as barriers to travel, and routes that include significant out-of-direction travel can further exacerbate this perception. Exhibit 2-3 shows the out-of-direction travel encountered when traversing an RCUT intersection. Each location where pedestrians must cross a motor vehicle path presents a potential risk, and these crossings should be minimized and appropriately designed to manage that risk. It may be necessary, often, to balance pedestrian route length with the number of crossings to maintain a tolerable pedestrian environment within the intersection. Additionally, pedestrian comfort and perceptions of safety are affected by their proximity to traffic, so adequate street buffers should be incorporated into the design to increase the pedestrian distance from moving vehicles. Chapter 4 includes more details on these design details and their evaluation. 2.3 Wayfinding Wayfinding refers to the process by which a pedestrian navigates an intersection. Exhibit 2-4 shows wayfinding at a DDI. At A.I.I.s, vehicular, pedestrian, and bicycle paths that differ from simple intersections may make wayfinding more challenging. Wayfinding can be more compli- cated for blind pedestrians than for sighted pedestrians due to the inability to detect visual cues available to sighted pedestrians. NCHRP Research Report 834 provides detailed information derived from research at round- abouts and channelized turn lanes regarding wayfinding and crossing problems and solutions Exhibit 2-3. Traversing task illustrated at an RCUT intersection.

2-8 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges for pedestrians with vision disabilities (14). Many of the same issues may be present at A.I.I.s, and Sections 2.3 through 2.4 of this report are derived from the information in NCHRP Research Report 834. Given their experience and familiarity with conventional intersections, pedestrians are accus- tomed to walking in a generally direct path between contiguous quadrants of an intersection. In some A.I.I.s, however, the pedestrian route with the fewest conflicts or shortest travel time may not be the most obvious, and a pedestrian expecting a straight path between intersection quadrants may need to travel out-of-direction for some part of the trip. Out-of-direction travel for pedestrians should be minimized in any design. Where it cannot be eliminated, the designer may need to incorporate guidance to show pedestrians how to reach their destination. For very large A.I.I.s, it may be useful to follow the principles of the wayfinding process that help people spatially orient themselves: orientation, route decision, route monitoring, and destination recognition (15). Traditional wayfinding signage facilitates this process by provid- ing sign assemblies for routing decisions, routing confirmation, and turns needed for specific destinations (3, 5). Additional design considerations to ease pedestrian travel through a complex walking envi- ronment may include • Providing high-visibility crosswalks, including preservation of the visibility of the crosswalk and other pavement markings through routine maintenance; • Locating pedestrian pushbuttons in accessible locations near the crossing and placed on the side of the pole where pedestrians will approach the pushbutton; • Where staged crossings are needed, installing pedestrian pushbuttons at intermediate dwell- ing locations to avoid trapping pedestrians on median islands or other mid crossing locations; • Providing accessible signals for people with vision disabilities to help with orientation to pre- ferred crossing locations; • Providing lighting along the preferred walking route; • Providing wayfinding kiosks to illustrate the preferred routes for pedestrians using both visual and tactile methods on the kiosk display; and • Providing pavement markings for pedestrians to indicate from which direction traffic is coming (see Chapter 9, Section 9.5). 2.3.1 Determining the Appropriate Crossing Location Pedestrians who are blind and approaching an intersecting street intending to cross and con- tinue in their direction of travel often assume that they are within the width of the crosswalk as they approach and that the crosswalk will continue across the street in the same direction they Exhibit 2-4. Wayfinding task illustrated at a DDI.

Pedestrians 2-9 have been traveling. They may also assume that vehicles idling on the street they want to cross are stopped at a stop line parallel to the direction of the crosswalk. The typical techniques used by a blind pedestrian intending to continue in their direction of travel is to stop when they reach a curb or a location that seems to be a curb ramp, check features with their cane, and listen to traffic. Pedestrians then cross from that location if they believe motorists have stopped or are yielding to them. This set of techniques may not be effective at finding a crosswalk at many A.I.I.s. If there is a landscaped, unwalkable, or otherwise detectable edge as a traveler approaches the intersection, a blind pedestrian may follow (i.e., trail) along that edge, looking for the intersect- ing sidewalk or curb ramp. If there is not a detectable edge, some individuals may follow the curb while using their canes, looking for a sloped area that may be a curb ramp, or for a detectable warning surface. Some dog guide users may seek a detectable warning surface with their feet if they are uncertain about the location of a crosswalk. However, some individuals will cross from the point at which they contact a curb, not wanting to risk becoming disoriented while looking for a curb ramp. 2.3.2 Aligning to Cross Blind pedestrians typically use two primary strategies to align when preparing to cross at a typical intersection. To establish a heading to the desired location on the opposite side of the street, travelers often assume they will be continuing to travel in the same direction as they were traveling when they approached the intersection. The first strategy is to use auditory and tactile cues to maintain that line of travel. The second strategy is to align with the sound of traffic pro- ceeding straight ahead on the street parallel to the travel direction (16, 17, 18) and/or to square off (i.e., directly face the loudest point) of traffic moving perpendicular to their path. When traffic is flowing on the street adjacent to them as they cross, it is then assumed to be flowing in the same direction as the crosswalk (i.e., parallel), helping with both initial alignment and maintaining alignment during crossing. This is an effective strategy at intersections with traditional geometry, because the traffic is normally moving parallel to the crosswalk. However, in some A.I.I.s, the crosswalk may not lie straight ahead in alignment with the sidewalk as one approaches an intersection. Depending on the location of the crosswalk and the geometry of the intersection: • Traffic direction may not give adequate auditory cues to the orientation of the crosswalk. • Traffic movement may not coincide with a safe pedestrian crossing opportunity. • Traffic may not be traveling perpendicular to the crosswalk. • Traffic may be moving on both sides of the crosswalk nearby. • Traffic may be flowing in an unexpected counterflow direction adjacent to the crosswalk. These conditions may confuse a person with vision disabilities attempting to cross the roadway. Absent traffic traveling parallel to their crossing direction, individuals who are blind may attempt to align with (or square off with) the traffic traveling across the crosswalk perpendicular to their travel path. The success of this strategy depends on the angle and location of the cross- walk in relation to the traffic movement. Pedestrians who are blind may also judge alignment based on the street gutter and align themselves so they are perpendicular to the gutter or the curb line on each side of the ramp. To offset the potential routing challenges a person with vision disabilities may encounter moving through an A.I.I., it is important to provide curb ramp designs that help a person orient to the desired crossing and to install APS where signalization is provided.

2-10 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges Curb ramps should slope and align in the direction of travel to the associated crosswalk to serve as a wayfinding aid for pedestrians who are blind. Curb ramps should serve a single direc- tion of pedestrian travel (i.e., directional curb ramps), rather than serving two diverging cross- walks via a diagonal curb ramp. Diagonal curb ramps require people in wheelchairs to enter the street at an angle and then turn in their desired direction (6). They also do not direct people with vision disabilities into the correct crossing. Detectable warning surfaces, used to indicate where a pedestrian is crossing from the sidewalk into the roadway, are not intended as an alignment cue, and neither pattern nor the edge of the detectable warning results in accurate alignment for crossing (19). Therefore, although they may affect alignment, neither the slope of curb ramps nor how truncated dome detectable warnings are installed are usually considered reliable sources of information for aligning to cross. Despite this unreliability, many blind pedestrians attempt to use a combination of the slope of the curb ramp, the gutter of the street, and the detectable warning surface as additional alignment infor- mation. While this is a strategy that may work for some blind pedestrians absent other cues, it is not recommended as a design strategy for A.I.I.s. 2.3.3 Maintaining Correct Heading while Crossing The act of maintaining correct heading while crossing is a wayfinding task distinct from the act of determining when to cross and complete the crossing. The primary strategy used by pedestrians who are blind to maintain their heading and travel straight across crosswalks at signalized and stop-controlled intersections is to travel parallel to straight-ahead traffic on the street beside them as they cross (20, 21). This strategy is not useful at A.I.I. crossings where traffic may not be moving straight ahead, parallel to the crosswalk. Where there are channelized lanes, this strategy may work for the main part of the intersection, but not at the channelized lane crossing. At shorter crossings, the need for additional information while crossing is miti- gated by the shorter distance. As long as individuals are properly aligned to begin the crossing, they will usually complete the crossing within the crosswalk if there are only one or two lanes. The likelihood of veering out of the crosswalk increases with crosswalk length. An accessible pedestrian signal or other treatment with an audible message, if present, may serve as a far-side audible beacon to help with maintaining heading. 2.4 Crossing The crossing task consists of determining when to enter a crosswalk and then completing the crossing—an action distinct from wayfinding tasks of maintaining alignment while crossing. Exhibit 2-5 shows crossing at a DLT intersection. A crossing opportunity generally exists when either a sufficient gap exists between conflicting vehicles or a driver yields. In addition, these opportunities can be enhanced with traffic control devices that assist in assigning right-of-way (e.g., pedestrian signals). Most A.I.I.s feature a combination of signalized crossings (typically at the main intersection) and uncontrolled crossings (typically across channelized lanes, but sometimes across the major legs). Crossing type, crossing length, and vehicle speeds are key factors in the safety of a crossing and become key variables in the assessment framework dis- cussed in Chapter 4 of this guidebook. 2.4.1 Street Crossings for Pedestrians Who Are Blind Like wayfinding, this task can be more challenging for pedestrians with limited vision than for pedestrians with full vision. At A.I.I.s, unexpected vehicular movements can present unique

Pedestrians 2-11 challenges to pedestrians. The potential for vehicles to be approaching from an atypical direc- tion can be confusing. In the United States, pedestrians are taught from an early age to look left, look right, look left, and then cross. There is the possibility in an A.I.I. that traffic may not come from a “typical” direction, which may cause confusion (particularly for those with cogni- tive disabilities) or cause a person to miss detecting close approaching vehicles. Some DDIs, for example, have used “LOOK RIGHT” pavement markings (particularly at unsignalized crossings) to inform pedestrians about traffic movements and where to look for approaching traffic. The same information needs to be communicated to pedestrians who are blind, which may require the use of audible devices with custom speech messages. At signalized crossings of typical orthogonal intersections, pedestrians who are blind or have low vision typically listen to the movement of traffic, along with APS, if present, to determine when to cross. Stopping traffic on the cross street, combined with the surge of traffic on the street parallel to the crosswalk, can provide a relatively strong confirmation of APS information and cues to the signal changes. At unsignalized crossings, the pedestrian who is blind has two types of crossing opportuni- ties: (1) when there is a gap in traffic such that no approaching vehicle can reach the cross- walk before the crossing is completed, or (2) when vehicles have yielded (19). The yield crossing can be in the form of a voluntary yield maneuver by drivers or may involve crossing in front of the vehicle(s) that have stopped or are stopping just upstream of the crosswalk for other reasons (e.g., queuing). When crossings are at high-speed locations, drivers are less likely to yield to a pedestrian preparing to cross. For those who are totally blind, these decisions must be made using sound cues alone. Individuals with low vision may be able to visually observe vehicles stopping or visually detect a gap in traffic within certain distances or locations in rela- tion to the crosswalk. 2.5 Design Principles for Pedestrian Facilities This section summarizes the key design principles for designing for pedestrians at an A.I.I. These principles should be considered in balance with the needs for other modes, recogniz- ing that tradeoffs will likely be needed for a given context and constraint. There will be cases where A.I.I.s are proposed for very constrained areas, and these constraints may be used to justify Exhibit 2-5. Crossing task illustrated at DLT intersection.

2-12 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges reductions or elimination of elements for pedestrian safety and/or comfort unnecessarily. Three primary categories of design principles for pedestrian facilities are discussed below: • Pedestrian Routing and Delay • Minimizing Conflicts with Motor Vehicles • Minimizing Conflicts with Bicycles Efforts should be made to include as many positive pedestrian features as possible in the given context and constraints. Sometimes, a different intersection form may provide a better balance of these tradeoffs. 2.5.1 Pedestrian Routing and Delay The design principles associated with best practices for pedestrian routing and minimizing delay are as follows: • Provide a highly visible and coherent route; • Consider pedestrian desire lines and reducing out-of-direction travel; • Minimize grade changes (unless grade separation is provided); • Minimize the use of multistage crossings unless a multistage crossing can reduce delay or eliminate crossings of high-volume, free-flow ramps; and • Minimize pedestrian exposure to high-speed and/or high-volume traffic movements. Exhibit 2-6 shows “pedestrian routing and delay” principles at an RCUT intersection. 2.5.2 Minimizing Conflicts with Motor Vehicles Design principles associated with best practices for minimizing conflicts between pedestrians and motorists are as follows: • Maximize visibility between pedestrians and motorists, by providing – Pedestrian crossings in conspicuous locations where there are clear sightlines between motorists and pedestrians. – Pedestrian crossings as perpendicular to conflicting motorists as possible. – Adequate lighting at the crossing locations. • Reduce motor vehicle speeds at conflict areas with uncontrolled or concurrent motor vehicle movements by – Limiting motor vehicle speeds to 20 mph or less where a pedestrian and motorist path cross. – Minimizing or avoiding the use of high-speed merging lanes and free-flow traffic movements. Exhibit 2-6. Pedestrian routing and delay principles.

Pedestrians 2-13 – Minimizing corner radii to slow turning speeds. – Using traffic calming measures such as raised crossings. • Minimize the severity of conflicts where they cannot be eliminated by – Separating movements in time using traffic controls. – Separating movements in space using geometry. – Minimizing exposure to conflicts with motorists by providing short crossing distances. – Minimizing the speed of vehicles at conflict points. • Provide adequate signal timing for pedestrians to clear crossings before permitting conflict- ing movements to proceed (i.e., by providing pedestrian lead, lag, or exclusive phases when appropriate). Exhibit 2-7 shows “minimize conflicts with motor vehicles” principles at a DDI with con- trolled turns from the off-ramp. 2.5.3 Minimizing Conflicts with Bicyclists Design principles associated with best practices for minimizing conflicts between bicyclists and pedestrians are as follows: • Maximize visibility between bicyclists and pedestrians. • Provide separated bike lanes at locations with higher volumes of bicyclists or pedestrians where bicyclists are likely to operate on a sidewalk due to traffic speeds over 30 mph or traffic volumes over 6,000 vehicles/day on the roadway. • Where separated bike lanes are provided, continue to separate bicyclists and pedestrians at crossings. • Ensure shared-use paths are wide enough to service anticipated volumes while minimizing conflicts (understanding that, even in low-volume locations, people will walk or bicycle side by side when traveling in groups). • Provide wide curb ramps that match the full width of shared-use paths. Exhibit 2-8 shows “minimize conflicts with bicyclists” principles at a DDI. Exhibit 2-7. Minimize conflicts with motor vehicles principles.

2-14 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 2.6 References 1. AASHTO. 2004. Guide for the Planning, Design, and Operation of Pedestrian Facilities. AASHTO, Wash- ington, DC. 2. Americans with Disabilities Act (ADA) of 1990, as amended. https://www.ada.gov/pubs/adastatute08.htm. Accessed March 7, 2019. 3. FHWA. 2009. Manual on Uniform Traffic Control Devices (MUTCD). https://mutcd.fhwa.dot.gov/index.htm 4. Institute of Transportation Engineers (ITE). 2014. Recommended Design Guidelines to Accommodate Pedes- trians and Bicycles at Interchanges: An ITE Proposed Recommended Practice. 5. National Association of City Transportation Officials (NACTO). 2014. Urban Bikeway Design Guide. Island Press. 6. United States Access Board. 2011. Proposed Guidelines for Pedestrian Facilities in the Public Right-of-Way (PROWAG). https://www.access-board.gov/guidelines-and-standards/streets-sidewalks/public-rights- of-way/proposed-rights-of-way-guidelines 7. FHWA. Federal Highway Administration University Course on Bicycle and Pedestrian Transportation. Lesson 8: Pedestrian Characteristics. Publication No. FHWA-HRT-05-099. https://www.fhwa.dot.gov/publications/ research/safety/pedbike/05085/chapt8.cfm. Accessed March 24, 2019. 8. TRB. 2016. Highway Capacity Manual, Sixth Edition. Transportation Research Board of the National Acad- emies, Washington, DC. 9. United States Access Board. 2010 ADA Standards for Accessible Design. https://www.ada.gov/regs2010/2010 ADAStandards/2010ADAstandards.htm. Accessed March 26, 2019. 10. FHWA. Pedestrians and Accessible Design. https://www.fhwa.dot.gov/programadmin/pedestrians.cfm. Accessed March 26, 2019. 11. Bertullis, T., and D. Dulaski. 2014. “Driver Approach Speed and its Impact on Driver Yielding to Pedestrian Behavior at Unsignalized Crosswalks.” Transportation Research Record 2464. Transportation Research Board of the National Academies, Washington, DC. 12. Fitzpatrick, K., S. Turner, M. Brewer, P. Carlson, B. Ullman, N. Trout, E. S. Park, J. Whitacre, N. Lalani, and D. Lord. 2006. NCHRP Report 562: Improving Pedestrian Safety at Unsignalized Crossings. Transportation Research Board of the National Academies, Washington, DC. 13. National Highway Traffic Safety Administration (NHTSA). Pedestrian Safety. https://www.nhtsa.gov/ road-safety/pedestrian-safety. Accessed March 26, 2019. Exhibit 2-8. Minimize conflicts with bicyclists’ principles.

Pedestrians 2-15 14. Schroeder, B., L. Rodegerdts, P. Jenior, E. Myers, C. Cunningham, K. Salamati, S. Searcy, S. O’Brien, J. Barlow, and B. Bentzen. 2016. NCHRP Research Report 834: Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook. Transportation Research Board of the National Academies, Washington, DC. 15. Lidwell, W., K. Holden, and J. Butler. 2003. Universal Principles of Design. Rockport Publishers. 16. Barlow, J. M., B. L. Bentzen, D. Sauerburger, and L. Franck. 2010. “Teaching travel at complex intersections.” In W. Wiener, R. Welsh & B. Blasch. (Eds.), Foundations of Orientation and Mobility, 3rd ed., Vol. 2. American Foundation for the Blind, New York, NY. 17. Guth, D. A., J. J. Rieser, and D. H. Ashmead. 2010. “Perceiving to move and moving to perceive: Control of locomotion by students with vision loss.” In W. Wiener, R. Welsh & B. Blasch (Eds.), Foundations of Orientation and Mobility, 3rd ed., Vol. 1. American Foundation for the Blind, New York, NY. 18. Stollof, E. 2005. “Wayfinding at intersections: Efforts toward standardization—A joint workshop of the Institute of Transportation Engineers and the U.S. Access Board.” ITE Journal, Vol. 75 No. 4, pp. 20-25. 19. Scott, A., J. Barlow, D. Guth, B. L. Bentzen, C. Cunningham, and R. Long. 2011. “Walking between the lines: Nonvisual cues for maintaining heading during street crossing.” Journal of Visual Impairment and Blindness, 105: pp. 662-674. 20. Hill, E., and P. Ponder. 1976. Orientation and Mobility Techniques: A Guide for the Practitioner. American Foundation for the Blind, New York, NY. 21. Jacobson, W. J. 2013. The Art and Science of Teaching Orientation and Mobility to Persons with Visual Impair- ments: Second Edition. American Foundation for the Blind, New York, NY.

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Alternative Intersections and Interchanges (A.I.I.s) are designs that improve operations and safety for motorized traffic by strategically adjusting the geometric features at a given location, working on the general principle of redistributing motor vehicle demand at an intersection in an attempt to limit the need to add capacity with new lanes to improve traffic flow.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 948: Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges provides specific guidance for four common A.I.I.s: Diverging Diamond Interchange (DDI), Restricted Crossing U-Turn (RCUT), Median U-Turn (MUT), and Displaced Left-Turn (DLT).

These designs may involve reversing traffic lanes from their traditional directions, which may introduce confusion and create safety issues for pedestrians and bicyclists. In addition, pedestrian paths and bicycle facilities may cross through islands or take different routes than expected. These new designs are likely to require additional information for drivers, bicyclists, and pedestrians as well as better accommodations for pedestrians and bicyclists, including pedestrians with disabilities.

NCHRP 20-44(35) is the implementation project for NCHRP Research Report 948. The implementation project's objective is to share and disseminate the research results with public agencies and provide hands-on technology transfer assistance to these agencies. Find project outcomes, including webinars and training materials, on the implementation project page.

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