Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges (2021)

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3-1 Bicycles are used for commuting, accessing transit, traveling to the store and to visit friends, recreation, and exercise. Although highly confident bicyclists may be comfortable riding with motor vehicles in large or complex intersections, including A.I.I.s, many bicyclists will view these intersections as barriers to mobility if such intersections have not been designed to facili- tate bicycle travel. The potentially large intersection footprint, the complexity of vehicle (and bicycle) movements, and potentially high vehicular traffic speeds and volumes prevalent in these intersections can present significant challenges to people cycling. The design of A.I.I.s should consider the needs of bicyclists traversing the intersection, as well as wayfinding and crossing concerns—especially when bicyclists use a separate path. Design decisions for bikeway types and crossing treatments should prioritize safety while considering the demographics and abilities of people likely to ride within the A.I.I. A.I.I.s should be designed to be as nonthreatening as possible to vulnerable road users. Bicycle facility design techniques in these settings should provide adequate bikeway width and separa- tion from motor vehicle traffic while minimizing exposure to conflicts and high-speed vehicles. Depending on the context, full separation may not be necessary or feasible, but the selection of bicycle facility type should be considered in the early stages of an A.I.I. design. Facility selection is explored in Section 3.3.5. 3.1 Characteristics of Bicyclists Given their exposure, bicyclists are at risk of severe injury in even minor crashes with motor vehicles. This vulnerability has proven to affect perceptions of traffic danger, which greatly influ- ence whether people bicycle, where they bicycle, and how they operate their bicycles. As bicycling becomes more popular, communities are seeking to encourage more people to choose bicycles as a mode of transportation. Perceptions of traffic danger influence bicyclist tolerance for traffic stress, as well as comfort when riding with or near motor vehicle traffic. Most people prefer to ride bicycles in space dedicated to that purpose, separated from and with as few interactions with motor vehicles as possible. Bicyclists also differ in their confidence levels and riding abilities. People who ride bicycles can be categorized into one of three groups based on their confidence (1); these categories are illustrated in Exhibit 3-1. The categories are useful for anticipating the design needs of the expected bikeway user within an A.I.I. and are as follows. • Highly Confident Bicyclists. The smallest proportion of bicyclists, these riders have a high tolerance for traffic stress and prefer direct routes, even if it requires mixing with motor vehicle traffic. Although they also enjoy separated bike facilities, they may avoid bikeways they perceive to be less safe, too circuitous, or too congested with other bicyclists and/or pedestrians. C H A P T E R 3 Bicycles

3-2 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges • Somewhat Confident Bicyclists. Somewhat Confident Bicyclists make up a slightly larger percentage of the bicycling population than Highly Confident Bicyclists. They actually tend to bicycle more frequently than Highly Confident Bicyclists, but are more selective about the types of bicycle facilities they will use. Their traffic stress tolerance is lower than that of Highly Confident Bicyclists, and they generally prefer low-volume residential streets and striped or separated bike lanes when bicycling on major streets. However, they will tolerate higher levels of traffic stress for short distances when necessary for key connections to avoid out-of-direction travel. • Interested but Concerned Bicyclists. Most people who ride bicycles or who want to ride bicycles fall into this category. They have the lowest tolerance for traffic stress and tend to ride only in locations with networks of separated bikeways or very low-volume streets with safe roadway crossings. To maximize the potential for bicycling as a viable transportation option, bicycle facilities need to meet the needs of the Interested but Concerned Bicyclist category. When bicyclists have been considered in the design of A.I.I.s, most designs have generally defaulted to configurations used only by those who are highly tolerant of traffic stress, or the Highly Confident Bicyclist. These designs leave the bicyclist to share travel lanes with motorists or to navigate the intersection in a striped, on-street bike lane. In most contexts, ranging from very rural to very urban, A.I.I.s have the potential to see bicy- clists from a wide cross section of the community, including children, older adults, and families. Many of these riders will fall within the Somewhat Confident and Interested but Concerned categories, and they will not be willing to share roadway space with motorists or endure high- stress crossings. This can result in bicycling on sidewalks or avoiding bicycling through the A.I.I. altogether if comfortable bicycle facilities are not provided. Exhibit 3-1. Bicyclist design user profiles. Source: FHWA Bikeway Selection Guide, Figure 6 (6).

Bicycles 3-3 3.2 Types of Bicycle Facilities Bicycle facilities can be differentiated based on their separation from motor vehicle traffic and/or the presence of a vertical physical barrier. Bikeways that provide dedicated space for bicyclists but do not include vertical barriers include • On-street bicycle lanes, and • In rural areas, shoulders designed to accommodate bicyclists. Conversely, bikeways that provide horizontal separation, vertical barriers, or both between bicyclists and motorists include • Separated bicycle lanes, also known as protected bicycle lanes or cycle tracks; and • Shared-use paths, also known as sidepaths when within the street right-of-way. In some cases, bicyclists may ride in a travel lane with motor vehicles; however, this is gener- ally appropriate only in low-speed, low-volume conditions. Bicycle treatments at a specific A.I.I. may largely be a function of which bikeway types exist on the streets connecting to it. However, even with on-street bike lanes, transitions can be designed on the approaches to A.I.I.s to allow bicyclists to move to more comfortable positions separated from motor vehicle traffic (see Chap- ter 5). Exhibit 3-2 provides images of various facility types. Given that implementation of A.I.I.s requires reconstruction or new construction, it is recom- mended that the highest quality bikeway be considered to maximize the comfort and safety of bicyclists operating through the A.I.I. 3.2.1 On-Street Bicycle Lanes On-street bike lanes provide dedicated space for bicycling and are differentiated from motor vehicle space by pavement markings and signing. Striped bike lanes may include a single stripe to designate the bike lane, or they may include a striped buffer space to separate bicyclists from motorists further. Striped bike lanes typically follow the routing of motor vehicles and are normally located to the right of motor vehicle travel lanes. Exhibit 3-2. Bicycle facility types, from left to right: shared-lane, on-street bike lane, buffered bike lane, two-way separated bicycle lane, and shared-use path.

3-4 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges The AASHTO Guide for the Development of Bicycle Facilities provides guidance on the sizing of bike lanes (3). Conventional striped bike lanes should be at least 5 feet wide, exclusive of the gutter space. The preferred width is at least 6 feet to better accommodate the bicyclist operating width and buffers from curbs and moving traffic. Bike lanes may need to be wider when there is a vertical barrier at the edge of the bike lane that is high enough for the bicycle handlebars to hit, such as at some DDIs. However, bike lanes 8 feet wide or more may be confused with on-street parking if such lanes are not properly marked and/or signed. Buffered bike lanes are generally preferable when bike lane space exceeds 7 feet in width. Separated bike lanes can also be provided when lane width exceeds 7 feet (see below). Buffered bike lanes have two components: the bike lane space, typically at least 5 feet exclusive of the gutter; and a painted buffer with diagonal or chevron hatching, typically at least 2 feet in width, to separate the bike lane from adjacent travel lanes horizontally (3). The values provided above represent design minimums and are not recommended widths. In general, more lateral clear- ance, including buffer width, is preferable. In high-speed, high-volume conditions, striped bike lanes are unlikely to see use by anyone but those bicyclists with the highest traffic stress tolerance (Exhibit 3-3). Further guidance on bikeway selection is presented in Section 3.3. 3.2.2 Separated Bicycle Lanes Like striped on-street bike lanes, separated bike lanes (also known as protected bike lanes or cycle tracks) establish a dedicated space for people to ride bicycles. However, separated bike lanes increase the safety and comfort of people riding a bicycle by physically separating their operating space from motor vehicle and pedestrian uses with vertical design elements. Vertical separation is provided with either a vertical object or a differentiation in elevation. Often, additional horizontal width is provided to improve separation from adjacent motorized traffic and to improve bicyclist comfort and safety. To emphasize the separation of a bikeway from pedestrian activity, it is preferable to provide a detectable edge for people with vision dis- abilities. The provision of a visual delineation in surface type or material has been used, although these visual treatments are insufficient for pedestrians with vision disabilities. For more information on the detailed design of separated bike lanes, see FHWA’s Separated Bike Lane Planning and Design Guide (4) and the Massachusetts Department of Transportation’s Exhibit 3-3. Example of on-street bicycle lanes at A.I.I.s in a high-speed, high-volume environment unlikely to see much use by bicyclists due to safety concerns.

Bicycles 3-5 Separated Bike Lane Planning and Design Guide (5), or the AASHTO Guide for the Develop- ment of Bicycle Facilities (3). Separated bike lanes (Exhibit 3-4) provide increased comfort in locations with higher speed, higher volume motor vehicle traffic. Bicyclists of all types prefer separated bike lanes and shared- use paths or sidepaths (see Section 3.2.3) in these higher stress environments. 3.2.2.1 One-Way Versus Two-Way Separated Bike Lanes While separated bike lanes may be one-way or two-way, a one-way configuration is preferable in most situations, because it establishes bicyclist travel patterns that are more consistent with motorist expectations. Matching motorist expectations in this way can create safer crossings at intersections and driveways. Two-way separated bike lanes generally require more complex transitions to directional bikeways at their endpoints, as well as more complex signal phasing to reduce or eliminate bicycle conflicts with turning motorists. Further detail on potential appli- cations of one-way versus two-way separated bike lanes can be found in the FHWA Bikeway Selection Guide (2). 3.2.2.2 Separated Bike Lane Widths Recommended widths for one-way separated bike lanes depend on the expected volumes of users. The preferred minimum width is 6.5 feet (exclusive of gutter widths) to provide space for faster bicyclists to pass those riding more slowly, with an absolute minimum of 5 feet (4). Where bicycle activity is expected to be high, the bike lane width should exceed 6.5 feet to allow for passing within the bike lane or side-by-side riding (4). For information about separated bike lane widths, see the FHWA Separated Bike Lane Planning and Design Guide (4), the Massachusetts Department of Transportation (MassDOT) Separated Bike Lane Planning and Design Guide (5), and the AASHTO Guide for the Development of Bicycle Facilities (3). 3.2.2.3 Separated Bike Lane Elevation and Materials A wide range of design treatments may be used to create separated bike lanes. Separated bike lanes may be implemented at sidewalk-level with some detectable division between the bikeway Exhibit 3-4. Example of separated bicycle lanes.

3-6 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges and pedestrian space on the sidewalk. Separated bike lanes may also be placed at street-level at the same elevation as motor vehicle lanes, or at an intermediate level above street-level and below sidewalk-level. The options for separation materials also vary. The greatest protection is usually offered by concrete curb separation; this separation may be provided by placing the bike lane at sidewalk- level or by constructing a curbed concrete island between travel lanes and the bike lane for intermediate- or street-level configurations. This is more common in new construction or reconstruction projects. For many retrofit projects and some reconstruction projects, lower-cost separation materials may be used for street-level separated bike lanes. These devices, including flexible delineators and rubber wheel stops, do not provide the same quality of comfort to bicyclists as concrete curb separation, because it is easier for motorists to drive over these devices and encroach into the bike lane. These materials are more appropriate in lower speed environments. In other cases, high-cost concrete barriers may be appropriate based on motorist speeds or in locations where there is limited space to increase the width of the buffer between the travel lanes and bike lanes. 3.2.3 Shared-Use Paths or Sidepaths Shared-use paths are paved facilities separated from motor vehicles and are designed for activity by both bicyclists and pedestrians. When located along a roadway within the street right-of-way, shared-use paths are known as sidepaths. These facilities are typically at least 10 feet wide, allow for travel in both directions, and are appealing to all types of bicyclists. Shared-use paths and sidepaths can increase the safety and comfort of people riding bicycles by using vertical and horizontal design elements to separate physically their operating space from that of motor vehicles. Paths with high volumes of bicyclists and pedestrians can have degraded comfort and safety as conflicts between users increase because of the two-way operation and shared operating space. The designer should consider the volume of users expected on a shared- use path, particularly the number of bicyclists and the potential for conflicts between users when determining the appropriateness of shared-use path facility and when determining an appropriate width. (See Chapter 4 for an explanation of the Shared-Use Path Level of Service tool that can be used to determine an appropriate path width.) In locations where use by bicyclists and pedestrians is expected to be high, additional width should be added to the shared-use path. Shy distance should also be added to the ultimate width of the shared-use path (see Chapter 5 for further discussion). Exhibit 3-5 provides an example of a shared-use path at a DDI. 3.3 Selecting a Bikeway Type and Width Every effort should be made to include a bikeway that provides bicyclists with a dedicated and safe space for their operation. As described in Section 3.2, separated bike lanes and shared-use paths are more suitable for providing dedicated bicycling space where motor vehicle traffic con- ditions are higher speed, higher volume, or both. Even on lower speed or lower volume streets, the intersection configuration may benefit from transitioning to a separated bicycle facility. Choosing the most appropriate bikeway type should be based primarily on the prevailing speeds and volumes of motor vehicles expected in the A.I.I. and a comparison of the benefits associated with each bikeway type.

Bicycles 3-7 In addition to selecting the bikeway type, the design parameters for the bikeway must be determined, such as width and separation type. These parameters will be based on various factors, including right-of-way and expected bicyclist and pedestrian volumes. 3.3.1 Expected Motor Vehicle Speeds and Volumes Often, A.I.I.s are implemented where motor vehicle throughput is meant to be optimized, which tends to correlate with locations where high volumes of motor vehicles are expected. The determination of an appropriate bicycle facility should be based on the planned traffic context as recommended by FHWA (2). For facilities in urban, urban core, suburban, and rural town contexts, the typical bicyclist is in the Interested but Concerned category. In these cases, FHWA provides guidance on selecting the most appropriate bikeway type based on adjacent motor vehicle speeds and volumes (2). Exhibit 3-6 provides a selection chart for facilities in the urban, urban core, suburban, and rural town contexts. The FHWA Bikeway Selection Guide provides additional guidance for using the chart. Often, the conditions found within an A.I.I. will exceed 30 mph or 6,000 vehicles per day; therefore, selecting a shared-use path or separated bike lane will often be the preferred choice. If the decision is made to select a bikeway type that is less appropriate for the conditions (e.g., implementing a buffered bike lane in place of a shared-use path), the designer should expect that fewer bicyclists will ride in the facility. Accordingly, the intersection may see lower-than-expected bicycle ridership, or there may be more instances of people riding bicycles on the sidewalks. In rural areas, FHWA provides guidance for selecting a shoulder-width to accommodate bicycles based on the adjacent motor vehicle speeds and volume (2). This table is given in Exhibit 3-7, which assumes a more confident cyclist will be the design user. However, if bicycle activity is expected to be common in rural areas (for example, in locations with bicycle tourism), a shared-use path or separated bike lane may be more appropriate. 3.3.2 Available Right-of-Way The amount of right-of-way that an A.I.I. needs can be larger or smaller than that for a con- ventional intersection for the same traffic volume, depending on the form of A.I.I. Often, the Exhibit 3-5. Example of shared-use path at a DDI with pavement markings to delineate two-way operation on each side of the roadway.

3-8 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges A.I.I. may take a shape that is more compatible with existing right-of-way constraints; this can allow the provision of a higher quality bicycle facility. A.I.I.s are also sometimes constructed in greenfield locations where adequate right-of-way is available for an optimal bikeway design. However, most A.I.I. projects have been retrofits for existing conventional intersections. One reason A.I.I.s are becoming increasingly popular in retrofit situations with right-of-way con- straints is that little-to-no additional right-of-way may be needed to redesign the intersection. However, if right-of-way acquisition is necessary to accommodate the required geometry for motor vehicles, the acquisition of right-of-way to accommodate other users should be included. If an A.I.I. requires less right-of-way than the existing conditions, every effort should be made to use that space for safe separated bicycle facilities. Preferred and minimum dimensions for the bicycle facility options were discussed in Sec- tion 3.2. Where right-of-way is constrained, tradeoffs may be required to achieve the preferred bikeway design. Options to adjust the intersection may include narrowing or reducing the number of travel lanes, narrowing center islands or channelization areas, reallocating landscaping space, reducing or eliminating shoulder widths, and other treatments to provide the preferred bikeway. There may be conditions where providing shared-use paths, which heighten bicyclist comfort at the potential expense of pedestrian comfort, could conserve more right-of-way than on-street or separated bike lanes. Similarly, there may be conditions where the bikeway Exhibit 3-6. Bicycle facility selection for urban areas. Source: FHWA Bikeway Selection Guide, Figure 9 (2).

Bicycles 3-9 dimensions could be narrowed to minimum dimensions. Narrowing bikeways or downgrading the quality of the bikeway should be among the last options considered in favor of preserving the preferred bikeway type. Changes to the bikeway design should be considered only after travel lanes and other areas have been narrowed to minimum practical values, recognizing that minimum widths for all elements are not an ideal outcome. 3.3.3 Expected Bicyclist Volumes Where lower pedestrian and bicycle activity is anticipated, it may be possible to use a shared- use path instead of separated bicycle and pedestrian facilities. In these cases, the FHWA Shared-Use Path Level of Service (SUPLOS) tool (see Chapter 4) should be used to determine if a shared-use path is an appropriate facility. The SUPLOS tool can help assess whether a shared-use path provides adequate width or if users would be better served by providing Exhibit 3-7. Bicycle facility selection for rural areas. Source: FHWA Bikeway Selection Guide, Figure 10 (2). .

3-10 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges sidewalks for pedestrians and separated bike lanes for bicyclists. If the SUPLOS score is pro- jected to be at or below C, separating bicyclist and pedestrian activity should be considered. Providing separate accommodations for bicyclists and pedestrians reduces the likelihood of crashes between the two user groups and minimizes the potential for frustrating interactions between users in a confined space. 3.3.4 Sight Distance An important design factor for street crossings is the provision of sight distance for bicyclists and motorists to view each other clearly on the approaches to any conflict points. Both parties should have the ability to perceive and react to a potential conflict, and motorists should be able to come to a full stop before conflicting with a bicyclist. The deceleration rate to come to this full stop should be no more than 5 feet/sec2, to minimize the risk of a vehicle-to-vehicle rear-end collision. That deceleration rate is consistent with AASHTO Green Book recommendations for drivers decelerating in approach to an uncontrolled intersection and is significantly less than the rate used for signal timing applications. This sight distance, which is needed at both uncontrolled and controlled crossings and relates to multiple-threat conditions, is discussed in Chapter 5. The design should provide adequate approach clear space before crossings by eliminating tall and opaque roadside elements that could limit visibility between motorists and vulnerable users approaching the crossing. 3.3.5 Facility Selection Summary Exhibit 3-8 summarizes the bicycle facility selection guidance based on FHWA (2). This table is useful as designers consider tradeoffs between different facility types. The assessment frame- work in Chapter 4 provides detailed guidance on how to select and evaluate bikeway facilities. 3.4 Design Principles for Bicycle Facilities The design of bicycle facilities requires consideration of factors that make bikeways safe and pleasant to use. Riding a bicycle is traditionally a human-powered activity (although using elec- tronically assisted bikes, or e-bikes, is on the rise), so consideration should be given to reducing route lengths and uphill grades that require additional effort. In the interest of safety for all users, designs should also seek to minimize the risk of crashes between bicyclists and motorists, as well as between bicyclists and pedestrians. Achieving these aims is guided by the principles in Sec- tions 3.3.1 through 3.3.3. Bicyclist comfort is not as tangible or readily quantifiable as delay or conflict points, but selecting the appropriate bikeway facility and designing it to serve the three listed purposes will promote a comfortable facility that encourages use. Design principles for bicycle facilities fall into three categories: • Bicyclist Routing and Delay • Minimizing Conflicts with Motor Vehicles • Minimizing Conflicts with Pedestrians Unless the design of an A.I.I. includes grade separation that fully separates motor vehicle movements from those of bicyclists and pedestrians (i.e., an overpass or underpass), the inter- action between motorists and these vulnerable road users will occur. The design of the A.I.I. should consider likely conflict scenarios and configure the intersection or signal phasing to manage conflicts between these users where possible. A design that minimizes or physically separates conflict points between motorists and bicyclists is also likely to result in greater atten- tiveness by all users at each crossing, resulting in a safer multimodal interaction. The design

Bikeway Type Design Alternative Benefits Considerations Shared-Use Path or Sidepath Recommended 10’ Minimum Width Provides a high level of comfort for bicyclists when pedestrian volumes are low to moderate. The design should include a minimum 2’ street buffer or vertical railing/barrier to separate path from travel lanes. Crossing treatments may be combined with pedestrian crossings. Preferred 12’-16’ Width Can allow for greater separation between bicyclists and pedestrians. Wider width accommodates higher volumes of bicyclists and pedestrians. The design should include a minimum 2’ street buffer or vertical railing/barrier to separate lanes. May require additional right-of-way. Additional width should be added to accommodate shy distances if railings or walls are used. Crossing treatments may be combined with pedestrian crossings. Separated Bike Lanes (also called Protected Bike Lanes or Cycle Tracks) Sidewalk-level Separated Bike Lane Separates bicyclists both vertically and horizontally from motorists. Also provides horizontal separation from pedestrians. Functions similarly to a shared-use path in terms of separation from motorists. Also provides horizontal separation from pedestrians. The bike lane width depends on expected demand. The preferred width is at least 6.5 feet, the minimum width is 5 feet. Requires ADA-compliant tactile separation from sidewalks to avoid pedestrian encroachment. Provides similar levels of comfort as shared-use paths. May require special design treatments at crossings. Enhanced treatments such as green pavement are recommended. Note: green paint is an interim approval (IA-14) from FHWA. Intermediate- level Separated Bike Lane Separates bicyclists both vertically and horizontally from motorists and pedestrians. The bike lane width depends on expected demand. The preferred width is at least 6.5 feet; the minimum width is 5 feet. Construction may be more challenging than sidewalk-level or street-level separated bike lanes. Provides similar levels of comfort as shared-use paths. May require special design treatments at crossings. Enhanced treatments such as green pavement are recommended. Note: green paint is an interim approval (IA-14) from FHWA. Exhibit 3-8. Summary of bicycle facility types. (continued on next page)

Exhibit 3-8. (Continued). Street-level separated bike lane with Concrete Curb Separation Concrete curb separation is more effective than other street-level separation devices for preventing encroachment by motorists. Concrete curb separation should be at least 2-ft wide where adjacent to travel lanes. The bike lane width depends on expected demand. The preferred width is at least 6.5 feet; the minimum width is 5 feet (exclusive of the gutter). Crossing treatments may be similar to conventional bike lanes. Enhanced treatments such as green pavement are recommended. Note: green paint is an interim approval (IA-14) from FHWA. Bikeway Type Design Alternative Benefits Considerations Street-level Separated Bike Lane with Other Types of Separation (e.g., Flexible Delineators) Visually delineates bicyclist space. Offers more bicycling space than conventional bike lanes. Separation with flexible delineators, wheel stops, and other nonconcrete devices is less effective for protecting occupants of the bike lane. The bike lane width depends on expected demand. The preferred width is at least 6.5 feet; the minimum width is 5 feet (exclusive of the gutter). Crossing treatments may be similar to conventional bike lanes. Enhanced treatments, such as green pavement, are recommended. Note: green paint is an interim approval (IA-14) from FHWA. Striped Bike Lanes Buffered Bike Lanes Provides dedicated bicycling space with additional width to horizontally separate bicyclists from motorists. Does not provide adequate comfort for bicyclists in high-speed and/or high-volume roadway conditions. 4- to 6-foot preferred minimum bike lane width with minimum 2- to 3-foot buffer. Lack of vertical separation devices increases the likelihood of encroachment by motorists. Conventional Bike Lanes (i.e., single stripe designation) Provides dedicated bicycling space. Does not provide adequate comfort for bicyclists in high-speed and/or high-volume roadway conditions. 5-foot minimum bike lane width. Lack of vertical or horizontal separation increases the likelihood of encroachment by motorists. In high-speed, high-volume conditions, unlikely to be used by any but the Highly Confident Bicyclist.

Bicycles 3-13 should also apply techniques to reduce crash severity by reducing motorist speeds, improving sight distance, and implementing other safety treatments. A design that minimizes or physi- cally separates conflict points between motorists and bicyclists is also likely to result in greater attentiveness by all users at each crossing, resulting in a safer multimodal interaction. 3.4.1 Bicyclist Routing and Delay The design principles associated with best practices for bicyclist routing and minimizing delay are as follows: • Provide a highly visible and coherent route. • If on-street bike facilities are provided, bicyclists should be able to proceed through the inter- section in a relatively straight line. To this end, provide lane line extensions to guide bicyclists through wide intersections. If a straight line cannot be achieved, designs should avoid abrupt turns for bicyclists. • Consider bicycle desire lines and reduce out-of-direction travel to accommodate both through and turning movements. • 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. • Minimize bicyclist exposure to high-speed and/or free-flowing traffic movements. Exhibit 3-9 shows “bicycle routing and delay” principles at a MUT intersection. 3.4.2 Minimizing Conflicts with Motor Vehicles The design principles associated with best practices for minimizing conflicts between bicyclists and motorists are as follows: • Maximize visibility between bicyclists and motorists. – Provide bicycle crossings that are as perpendicular to conflicting motorists as possible. – Provide bicycle crossings in conspicuous locations where there are clear sightlines and adequate sight distance between motorists and bicyclists. – Provide adequate lighting at the crossing locations. • Maintain separated bicycle facilities or transition bicyclists to off-street facilities near high- speed and/or high-volume conflict areas. Exhibit 3-9. Bicycle routing and delay principles.

3-14 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges • Reduce motor vehicle speeds in conflict areas. – Limit speeds to 20 mph or less where bicyclist and motorist paths cross. – Minimize or avoid the use of conflicts with high-speed merging lanes and/or high-volume traffic movements. – Minimize corner radii to slow turning speeds. – Use traffic calming measures such as raised crossings. • Minimize the severity of conflicts where they cannot be eliminated. – Separate movements in time using traffic controls as well as with geometric separation when feasible. – Minimize exposure to conflicts with motorists by providing short crossing distances and physically separated bikeways. – Avoid designs that require bicyclists to merge across multiple lanes of traffic. – Minimize speed differential at conflict points. • Provide adequate signal timing for bicyclists to clear intersections before permitting conflict- ing movements to proceed. Exhibit 3-10 shows “minimizing conflicts with motor vehicles” principles at a DLT inter- section. Note: not all conflict points are shown. 3.4.3 Minimizing Conflicts with Pedestrians The design principles associated with best practices for minimizing conflicts between bicy- clists and pedestrians are as follows: • Maximize visibility between bicyclists and pedestrians. • Where separated bike lanes are provided, continue to separate bicyclists and pedestrians at crossings. • In shared-use paths, ensure there is adequate width for safe passing by bicyclists and pedestrians. • Provide curb ramps that match the full width of shared-use paths. Exhibit 3-11 shows “minimizing conflicts with pedestrians” principles at a MUT intersection. Exhibit 3-10. Minimizing conflicts with motor vehicles principles.

Bicycles 3-15 3.5 References 1. Dill, J., and N. McNeil. 2016. “Revisiting the Four Types of Cyclists.” Transportation Research Record 2587. Transportation Research Board of the National Academies, Washington, DC. 2. Schultheiss, B., D. Goodman, L. Blackburn, A. Wood, D. Reed, and M. Elbech. February 2019. Bikeway Selec- tion Guide. Report FHWA-SA-18-077. Federal Highway Administration, Washington, DC. 3. AASHTO. 2012. Guide for the Development of Bicycle Facilities, Fourth Edition. AASHTO, Washington, DC. 4. FHWA. 2015. Separated Bike Lane Planning and Design Guide. https://www.fhwa.dot.gov/environment/ bicycle_pedestrian/publications/separated_bikelane_pdg/page00.cfm 5. MassDOT. 2015. Separated Bike Lane Planning and Design Guide. MassDOT, Boston, MA. https://www. mass.gov/lists/separated-bike-lane-planning-design-guide Exhibit 3-11. Minimizing conflicts with pedestrians principles.