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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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Suggested Citation:"Chapter 29: Bicyclists." National Academies of Sciences, Engineering, and Medicine. 2022. Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters. Washington, DC: The National Academies Press. doi: 10.17226/26473.
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HFG BICYCLISTS VERSION 2.1 29-1 B CHAPTER 29 BICYCLISTS Signals and Signal Timing for Bicycles at Intersections ........................................................... 29-2 Markings for Bicycles at Intersections ...................................................................................... 29-4 Bicycle Lanes ............................................................................................................................. 29-6 Separated Bicycle Lanes ............................................................................................................ 29-8 Contraflow Bicycle Lanes........................................................................................................ 29-10 Shared Use Lanes ..................................................................................................................... 29-12 Shared Bus-Bicycle Lanes ....................................................................................................... 29-14 Mitigating Heavy Vehicle Conflicts with Bicycles ................................................................. 29-16

HFG BICYCLISTS VERSION 2.1 29-2 SIGNALS AND SIGNAL TIMING FOR BICYCLES AT INTERSECTIONS Introduction Design for traffic signals at intersections are generally determined by motor vehicle use. This creates systems that are not timed for, nor designed to detect the presence of, other road users such as bicyclists, because they use the same roads and signal displays but have different operating characteristics and needs. Therefore designs made to accommodate bicyclists within the given road context are necessary. This guideline discusses signal timing and design countermeasures that can minimize conflicts with motor vehicles and improve bicyclist visibility and conspicuity. Design Guidelines The American Association of State Highway and Transportation Officials (AASHTO) (1) recommends using the following crossing times to ensure that a stopped or rolling bicyclist receives enough time to react to a green signal, accelerate, and cross the intersection before crossing traffic can enter. Note that in the forthcoming 2020 revision of AASHTO’s Guide for the Development of Bicycle Facilities, the typical attained bicycle crossing speed will likely be designated as 13 ft/s to encompass a broader range of cyclists (2). BICYCLE CROSSING TIME – METRIC VALUES [IMPERIAL VALUES] Where: BCTstanding = bicycle crossing time, s initially stopped V = attained bicycle crossing speed, m/s [ft/s] typical min. 4.5 m/s [14.7 ft/s] BCTrolling = bicycle crossing time, s initially rolling BD = braking distance, m [ft] W = intersection width, m [ft] PRT = perception reaction time, typical 1 s L = typical bicycle length (typical 1.8 m) [6 ft] a = bicycle acceleration typical 0.5 m/s2 [1.5 ft/s2] Intersection controllers that can detect if a bicycle is present should use the bicycle minimum green timing, below, instead of the minimum green timing normally calculated for vehicular traffic (1). BICYCLE MINIMUM GREEN TIME Where: BMG = bicycle minimum green time, s Y = yellow change interval, s BCTstanding = bicycle crossing time, s Rclear = all-red interval, s To provide sufficient time for a rolling bicyclist who enters the intersection at the end of a green interval, designers may need to adjust the red intervals and include extensions times using the following equation (1). ALL-RED AND EXTENSION TIME Where: BCTrolling = bicycle crossing time (s) Y = yellow change interval (s) Textension = extension time (s) Rclear = all-red interval (s) Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-3 Discussion Signal Timing: Whether in a road or bike lane, more experienced bicyclists can be comfortable entering intersections during mid-to-late green intervals, others tend to slow down when approaching a green signal in order to start at the beginning of a green interval (1). Youth bicyclists often use crosswalks and pedestrian push buttons to cross intersections, indicating that these facilities should be made available to bicyclists who rely on them to cross comfortably (1). Some traffic signal controllers have bicycle minimum green parameters which can be used with appropriate detection to provide bicyclists with enough time to clear the intersection (1). An all-red interval should be used to provide time for crossing bicyclists to pass beyond the far side of an intersection (1). Leading Bicycle Intervals: A leading bicycle interval (LBI) can reduce right-turn conflicts by giving bicyclists a head start and priority over turning motor vehicles (2). The leading interval increases bicyclist conspicuity by placing them ahead of other vehicles and making them the only travelers in the intersection during the interval. Through and right- turning bicycles should receive the LBI, followed by through and right-turning motor vehicles who must yield to bicyclists and crossing pedestrians who have not yet completed traversing the intersection (2). Bicycle Signal Heads (BSH): Bicycle signal heads are electrically powered traffic control devices that can be used where stand-alone bike paths or lanes cross a street (especially when the bicycle clearance time differs from the pedestrian clearance time). Their purpose is to split signal phases at intersections where bicycle movement conflicts with motor vehicle movement during a green phase, to give bicyclists an advanced green, or indicate an “all-bike” phase where bicyclist turning movements are highly common. Bicycle signal heads are most frequently placed at intersections with high numbers of bicycle and motor vehicle crashes, and at intersections near school zones (3). Bicycle signal heads can help separate bicycle movements from conflicting motor vehicle, streetcar, light rail, or pedestrian movements in urban settings. In addition, they can provide priority to bicycle movements at intersections and accommodate bicycle-only movements within signalized intersections, providing a measure of protection in high-conflict areas. Overall, they can help simplify movements through complex intersections (3). Bicycle signal heads must be placed in a location that is clearly visible to oncoming bicycles (3). If the bicycle phase is not set for each cycle, bicycle signals should be installed with appropriate detection and actuation (3). Adequate clearance intervals, such as those in the design guidelines section above, should be provided to ensure that the bicyclists entering the intersection during the green phase can travel through the intersection so that conflicts with turning or entering vehicles are minimized (3). When the bicycle signal is used to separate through bicycles from right-turning vehicles, the right turn on red shall be prohibited while the bicycle signal is active (3). BSshould be large enough to be visible to bikers and vehicles across wide intersections (three lanes or more). Hybrid Beacons for Bike Route Crossing: Hybrid beacons have been modified by several cities from being pedestrian- focused to incorporating bicycle crossings (3). Hybrid beacons are used to enhance non-motorized crossings of major streets in places where crossing street volumes don’t support the installation of a conventional traffic signal and can be adapted to mid-block crossing locations as well (3). Installing bike signals and signal detection as supplementary measures along with hybrid beacons can be used to increase awareness and reduce conflicts during bicycle crossings of major streets (3). Hybrid beacons and possibly even RRFBs can be used to create gaps for bicyclists to cross busier streets and are associated with a very high driver compliance (3). Design Issues If the intersection controller does not have bicycle detection capabilities but a greater minimum green is needed for local bicyclists, increasing the minimum green time can be considered (1). Cross References Selecting Beacons to Improve Pedestrian Conspicuity at Crosswalks 28-10 Heuristics for Selecting the Yellow Timing Interval 11-6 References 1. American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition. 2. National Association of City Transportation Officials. (2019). Don’t Give Up at the Intersection. New York, NY. 3. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY.

HFG BICYCLISTS VERSION 2.1 29-4 MARKINGS FOR BICYCLES AT INTERSECTIONS Introduction Bicyclists are particularly vulnerable at intersections because they can be less noticeable or easy to miss due to their size. Further, large vehicles with increasingly wide A and B pillars, as well as drivers’ use of interactive screens within vehicles, increase the likelihood that a driver will fail to notice a bicyclist. Bicycle crashes with motor vehicles can be severe due to the bicycle’s lack of protective structures and their small mass relative to motor vehicles. This guideline discusses intersection lane marking countermeasures that can improve bicyclist visibility and conspicuity and minimize conflicts with motor vehicles. Design Guidelines Label Countermeasure a. Use through bike lanes (TBLs) to help correctly position cyclists to the left of right-turn lanes or to the right of left-turn lanes (1, 2). Using dedicated bicycle lanes can reduce the risk of injury by promoting more predictable bicyclist and motorist travel movements while alerting motorists to expect and yield to merging bicyclists (2). b. Apply dotted bike lane extensions to guide bicyclists through long, undefined areas at intersections and signify locations where motorists can safely merge into the turn lane (2, 3). c. Use position sharrows to paint an alignment that represents a practical path for bicycle travel (3). d. Install sharrows to increase operating space for bicyclists, reduce sidewalk riding, enhance motorist awareness of bicyclists, and distances bicyclists from parked vehicles (4, 5). e. Use mixing zone designs to evenly split the onus of merging between bicyclist and motorist, encouraging motorists to yield to bicyclists and reduce their speed within the turn lane (1, 2).  Examples of Designs for Bicycle Lanes at Intersections: Turning Zone with Post Restricted Entry and Through Bike Lane (TBL) Mixing Zone with Yield Entry Markings Source: adapted from Monsere et al. (1) Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-5 Discussion When planning the layout of intersections, designers must consider potential conflicts among all road users, not only between motorists. Though bike lanes next to left-turn lanes, as in the figure above, can help position bicyclists and reduce merging confusion between them and motorists. In one study comparing various intersection bike lane designs, this design had high correct lane use both by turning vehicles (87 percent) and through bicyclists (91 percent). This suggests a clear benefit of a restricted entry approach while creating a semi-protected TBL (1). Separate bicycle left-turn lanes should be considered when there are considerable volumes of left-turning bicycles or if a preferred bicycle route makes a left-turn (3). One tactic used to offer bicyclists a safe way to make left turns at multi-lane intersections from a right-side bike lane is installing two-stage turn queue boxes (2). These two-stage turns can provide more comfort to bicyclists making left turns, provide a formal queuing space for bicyclists making these turns, reduce turning conflicts between bicyclists and vehicles, prevent conflicts from bicyclists queuing in a bike lane or crosswalk, and separate turning bicyclists from through bicyclists (2). For right-turning lanes with mixing zones, such as in the figure above, video evaluation found that nearly all (93 percent) of the turning vehicles used the lane as intended—the highest compliance of all evaluated designs (1). Using mixing zones maintains bicyclist priority in the absence of a dedicated TBL and reduces the risk of right hook crashes at intersections (2). See Shared Use Lanes (page 29-12) for guidance on designing shared use lanes and their markings. Lane markings that control bicycle traffic should be presented in a way that all road users understand that the signal relates to the bicyclist (6). Clear marking, including vertical delineation, of the vehicle entry point to the turning lane is beneficial to all road users and reduces stress in bicyclists (1, 2). Bike lane markings straight through intersections can raise awareness for bicyclists and motorists for potential conflict areas, reinforce bicyclist priority over turning vehicles, make bicycle movements more predictable, and increase the visibility of bicyclists. Installation of bike boxes can lower the number of conflicts with and increase yielding behavior to bicyclists by ensuring that bicyclists waiting at red light intersections are visible to the first driver in the queue (2, 7, 8). Other benefits of bike boxes are that they reduce signal delays for bicyclists, help prevent right hook conflicts with turning vehicles at the start of the green indication, provide priority for bicyclists at signalized crossings of major streets, group bicyclists together to clear intersections more quickly, and benefit pedestrians through reduced encroachment of vehicles into crosswalks (2). Bike boxes that extend across all lanes at intersections can also facilitate left turn positioning for bicyclists and transitions from a right-side bike lane to a left side bike lane during red signal indications (2). With the presence of bike boxes, motorists give bicyclists the right-of-way more often, leading to 77 percent of bicyclists feeling safer moving through intersections using bike boxes (2). Conversions of traditional intersections to roundabouts have resulted in decreases in vehicular injuries and fatalities but increases in bicyclist injuries as well (9). Design considerations for roundabouts that enhance bicyclist safety are discussed in Accommodations for Bicyclists at Roundabouts (see page 30-8). Design Issues Corner radii at intersections should be as small as practical to reduce merging conflicts between bicyclists and motorists, as larger corner radii allow high vehicle turning speeds (3). While two-stage turn queue boxes can increase comfort for turning bicyclists, they also typically increase delays for these bicyclists since they must now wait to receive two separate green signals to make their turn (2). Cross References Bicycle Lanes 29-6 Accommodating Bicyclists at Roundabouts 30-8 References 1. Monsere, C. M., Foster, N., Dill, J., and McNeil, N. (2015). User behavior and perceptions at intersections with Turning and Mixing Zones on Protected Bike Lanes. Transportation Research Record: Journal of the Transportation Research Board, No. 2520, pp. 112–122. 2. https://tooledesign.com/project/update-to-the-aashto-guide-for-the-design-of-bicycle-facilities-2019/ 3. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY. 3. American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition. 4. Fitzpatrick, K., Chrysler, S. T., Van Houten, R., Hunter, W. W., and Turner, S. (2011). Evaluation of pedestrian and bicycle engineering countermeasures: Rectangular rapid-flashing beacons, hawks, sharrows, crosswalk markings, and the development of an evaluation methods report. 5. Foletta, N., Nielson, C., Patton, J., Parks, J., and Rees, R. (2015). Green Shared Lane Markings on Urban Arterial in Oakland, California: Evaluation of Super Sharrows. Transportation Research Record: Journal of the Transportation Research Board, No. 2492, pp. 61–68. 6. Goodno, M., McNeil, N., Parks, J., and Dock, S. (2013). Evaluation of Innovative Bicycle Facilities in Washington, DC: Pennsylvania Avenue Median Lanes and 15th Street Cycle Track. Transportation Research Record: Journal of the Transportation Research Board, No. 2387, pp. 139– 148. 7 Dill, J., Monsere, C., and McNeil, N. (2011). Evaluation of bike boxes at signalized intersections. 8. Taylor, S., Giang, C., Chau, P., and Aumann, P. (2017). Cycling aspects of austroads guides (Report No. 9781925451641). 9. Jensen, S. U. (2013). Safety Effects of Converting Intersections to Roundabouts. Transportation Research Record: Journal of the Transportation Research Board, No. 2389, pp. 22–29.

HFG BICYCLISTS VERSION 2.1 29-6 BICYCLE LANES Introduction Bicycle lanes refers to conventional and buffered bicycle lanes that use pavement markings to designate a portion of the roadway exclusively for bicyclists’ use. While designated bicycle lanes without a physical separation are not the preferred treatments for the majority of people who ride bikes, they can provide additional width to reduce crash potential by separating motor vehicles from bicycles, reducing ‘dooring’ from bicycles colliding with parked car doors, and increasing motor vehicle drivers’ awareness by indicating where they can expect bicyclists to be traveling. This guideline discusses methods for reducing bicyclists’ potential exposure to crashes and increase bicyclists’ comfort when designing bicycle lanes. Design Guidelines Conventional Bicycle Lanes  The desired width of bike lanes adjacent to a curb face is 6 ft. In cities where illegal parking in bike lanes is a concern, 5 ft. wide bike lanes or other physical separation may be preferred (1).  A bike lane next to a parking lane should be at least 5 ft. wide. When adjacent to a narrow parking lane (7 ft.) with high turnover, consider implementing a wider bicycle lane (6–7 ft.) (1, 2).  Add 2 ft. to bike lane widths when the lane is adjacent to a guardrail or physical barrier to provide a minimum shy distance from the barrier (1).  Lane markings used to separate motor vehicle lanes from the bike lane should be a solid white line that is 6-8 in. wide (1).  In most situations where a bicycle lane is adjacent to on-street parking, the suggested width for the parking lane is 8 ft. (3).  Strongly consider including bicycle lanes at sites with travel lane widths of between 16 and 18 ft., even when on-street parking is not allowed (3). Buffered Bicycle Lanes  The MUTCD indicates that buffers be marked by two solid white lanes and with a diagonal hatching or chevron markings if the buffer is 4 ft. in width or wider. NACTO guidelines recommend these markings when the buffer is 3 ft. in width or wider (1). Consider dashing the buffer boundary where vehicles are expected to cross at driveways (1).  Interior diagonal cross hatching should consist of 4 in. lines angled at 30 to 45 degrees and striped at intervals of 10 to 40 ft. Increasing striping frequency can lead to increased motorist compliance (1).  Where space permits, consider installing a narrower bicycle lane with a parking-side buffer rather than a wider bike lane with no buffer (3).  For buffered lanes next to on-street parking, a 5 ft. minimum lane width is recommended to encourage bicyclists to ride outside of the ‘door zone,’ where lane width includes the buffer widths (1). Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data Source: adapted from AASHTO (2) The figure on the left illustrates the recommended lane widths for streets with conventional bike lanes installed (2). The figure on the right shows three examples of different buffer area designs with the thicker line being adjacent to the motor vehicle lane (1). (a) (b) (c) Source: adapted from NACTO (1)

HFG BICYCLISTS VERSION 2.1 29-7 Discussion Bicycle lanes designate a space for bicyclists using pavement markings. In general, bike lanes enable bicyclists to ride at their preferred speed without interference from motor vehicle traffic and can facilitate predictable behaviors and movements between bicyclists and motor vehicles (1). Roadway geometry, available road width, and traffic density can dictate where and when to implement bike lanes. Conventional Bicycle Lanes: Conventional bike lanes are typically installed on the right side of the street between the adjacent travel lane, and the curb, road edge or parking lane (1). Conventional bike lanes are most helpful on streets with average daily traffic of more than 3,000 motor vehicles, on streets with posted speed limits that are greater than 25 mph, on streets with high transit vehicle volumes, and on streets with 10-12 ft. wide travel lanes (1, 3). Conventional bike lanes can be used to create separation between bicyclists and motor vehicles, visually remind motorists of bicyclists’ right to drive on the streets, encourage motor vehicles to stay in their lane when passing bicyclists, and increase bicyclist comfort and confidence on busier streets (1, 5, 6). If designing a bicycle lane next to a parking lane, minimizing the parking lane width in favor of increasing bike lane width will give bicyclists more space to keep outside of the ‘door zone’ (3). Because left side bicycle lanes are conventional bike lanes placed on the left side of one-way streets or two- way median divided streets, the guidance for the design of conventional bike lanes can be translated to left side bike lanes (1). Left side bike lanes offer the ability to minimize ‘door zone,’ bus stop, and loading zone conflicts (1). See the Contraflow Bike Lanes guidelines on page 29-10 for information about designing bicycle lanes that travel opposite the flow of traffic. Buffered Bicycle Lanes: Buffered bike lanes pair conventional bike lanes with a designated buffer space between the bike lane and the motor vehicle travel lane. These buffers can be installed on streets with extra lanes or extra lane width, and on streets with high travel speeds, high travel volumes, and/or high amounts of heavy vehicle traffic (1). Special consideration should be given for installing buffered bike lanes at transit stops to manage bicycle and pedestrian interactions (1). Buffered bike lanes can provide a wider shy distance between motor vehicles and bicycles, provide space for bicyclists to pass other bicyclists without encroaching onto the motor vehicle lane, encourage bicyclists to ride outside of the ‘door zone’ when the buffer is between the bicycle lane and parked cars, and encourage bicycle riding in general by contributing to an increased perception of safety among bicyclists (1, 3). Design Issues Not all roadways have enough space and/or width to accommodate bicycle lanes. A common lane reduction treatment is to convert an undivided four-lane (two-way) roadway to a three-lane roadway (central two-way left-turn lane). This provides space for bike lines on both sides of the road, moderates top speeds of vehicles because there is only one lane in each direction, eliminates the likelihood of multiple threat crashes, and reduces sideswipe crashes since motorists no longer change lanes to a right-side lane in order to pass left-turning vehicles (2). Striped or painted buffers offer a small increase in bicyclists’ comfort, whereas buffers with some sort of physical protection, even protection as minimal as a plastic flex post, yield significant increases in perceived comfort for potential cyclists with safety concerns (7). Cross References Markings for Bicycles at Intersections, 29-4 Shared Use Lanes and Contraflow Bicycle Lanes, 29-10 Separated Bicycle Lanes 29-8 Shared Bike/Bus Lanes 29-14 Mitigating Heavy Vehicle Conflicts with Bicycles 29-16 References 1. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY. 2. American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition. 3. Torbic, D. J., Bauer, K. M., Fees, C. A., Harwood, D. W., Van Houten, R., LaPlante, J., and Roseberry, N. (2014). NCHRP Report 766: Recommended Bicycle Lane Widths for Various Roadway Characteristics. Transportation Research Board, Washington, DC. 4. Federal Highway Administration. (2012). Manual on uniform traffic control devices for streets and highways. 2009 edition with revision numbers 1 and 2 incorporated. Washington, DC. 5. Mehta, K., Mehran, B., and Hellinga, B. (2015). Evaluation of the Passing Behavior of Motorized Vehicles When Overtaking Bicycles on Urban Arterial Roadways. Transportation Research Record: Journal of the Transportation Research Board, No. 2520, pp. 8–17. 6. Sando, T. (2014). Operational analysis of shared lane markings and green bike lanes on roadways with speeds greater than 35 mph. Jacksonville, FL: University of North Florida. 7. McNeil, N., Monsere, C. M., and Dill, J. (2015). Influence of Bike Lane Buffer Types on Perceived Comfort and Safety of Bicyclists and Potential Bicyclists. Transportation Research Record: Journal of the Transportation Research Board, No. 2520, pp. 132–142.

HFG BICYCLISTS VERSION 2.1 29-8 SEPARATED BICYCLE LANES Introduction Separated bicycle lanes are one or two-way exclusive bikeways parallel to the roadway yet physically separated from moving traffic. Separated bike lane barriers can consist of curb separations, landscaped medians, flexible delineators or bollards, or other vertical structures. They remove exposure to crashes and increase comfort by separating bicyclist and larger vehicles in areas in areas with higher traffic volumes and speeds. This guideline discusses strategies for implementing separated bike lanes. Design Guidelines  One-way separated bike lanes should be at least 5-7 ft. wide, while two-way lanes should be at least 12 ft. wide or 8 ft. in constrained locations (1, 2).  A dashed yellow line should be used to separate two-way bicycle traffic and distinguish the bicycle lane from any adjacent pedestrian areas (1).  If the separated bike lane is adjacent to a parking lane, the combined parking lane and buffer should be at least 11 ft. wide to discourage motor vehicle encroachment into the bicycle lane (1).  Barriers between the bicycle lane and motor vehicle traffic should have a minimum 3 ft. width. A minimum width of 1 ft. is possible with a mountable or vertical curb face (1, 2).  Bicycle lane word, symbol, and/or arrow markings (MUTCD Figure 9C-3 (3)) should be placed at the beginning of a cycle track and at periodic intervals along the facility based on engineering judgment (1).  A “DO NOT ENTER” sign (R5-1 (3)) with “EXCEPT BIKES” plaque should be posted along the facility to only permit use by bicycles (1).  For two-way separated bicycle lanes on one-way streets, a “ONE WAY” sign (R6-1, R6-2 (3)) with “EXCEPT BIKES” plaque should be posted along the facility and at intersecting streets, alleys, and driveways informing motorists to expect two-way traffic (1).  Intersection traffic control devices along the street should be installed and oriented toward bicyclists traveling in the contraflow direction (1).  For motor vehicles attempting to cross the separated bicycle lane from a side street or driveway, side furnishings and other features should accommodate a sight triangle of 20 ft. from minor street crossings and 10 ft. from driveway crossings (1, 2).  Consider implementing separated bike lanes using “Oasis Greenways” with landscaped barriers to provide natural separations from the roadway while achieving other benefits from a green environment (4).  Consider creating bike preferred or bike-only “Bike Boulevards” by implementing traffic calming on streets parallel to or near to a main arterial to provide a low-speed path to destinations in high traffic areas (4). The figure below is an example of a one-way separated bicycle lane with pedestrian and motor vehicle barriers from Dickman et al. (2). Example of a One-Way Separated Bicycle Lane (From Dickman et al. (2)) Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-9 Discussion Separation of bike lanes from motor traffic may be desirable for various reasons such as high traffic speeds, high traffic volumes, aggressive motor vehicle behavior, or general lack of consideration by drivers towards bicyclists’ use of roads (5). Additional separation from the sidewalk is valuable for reducing unwanted pedestrian encroachment into the bike lane (1, 2). The use of physical separation with vertical elements, unpaved separation, or detectable edges may be more effective than visual delineation at reducing unwanted encroachment into the bike lane (2). Separated bike lanes provide benefits for bicyclists by dedicating and protecting space for bicyclists in order to improve perceived comfort and safety, providing a more attractive facility for bicyclists of all levels and ages, eliminating the risk and fear of crashes with overtaking vehicles, reducing risk of ‘dooring’ (crashes in which the bicyclist rides into a motor vehicle’s open door) compared to a bike lane, and eliminating the risk of a ‘doored’ bicyclist being run over by a motor vehicle (1, 2). One- way separated bike lanes should be used on streets with parking lanes, streets for which conflicts at intersections can be effectively mitigated using parking lane setbacks, bicycle markings through the intersection and through other signalized intersection treatments, along streets with high bicycle volumes, and along streets with high motor vehicle volumes and/or speeds (1, 2). Two-way separated bike lanes violate drivers’ expectations and should only be used if there is not enough room for one-way separated bike lanes on both sides of the street, where contraflow bicycle travel is desired (see page 29-10), and on streets with extra space for right-of-way on one side (1). Separated bike lanes have also been especially useful to bicyclists when installed at connections between and among high-demand destinations such as schools, parks, transit stops; commercial areas; residential clusters; and disadvantaged populations (2, 6). Since many barriers cannot continue through an intersection or across driveways, treatments such as “Yield to Bikes” signage, colored pavement markings, yield lines, and signal adjustments should be used to manage conflicts between bicyclists and motorists at these locations and make it clear that the cycle track has priority over entering and exiting traffic (1, 5). Motor vehicle traffic crossing the cycle track should be channelized to make turns at sharp angles to reduce travel speed prior to the crossing (1). See Markings for Bicycles at Intersections (page 29-4) for guidelines on designing bicycle lane markings through intersections. Additional consideration should be given to install separated bike lanes around transit stops for managing bicycle and pedestrian interactions (1). Placing a separated bike lane on the left side of a one-way street (out of the way of transit stops along the right side) or choosing to install a separated bike lane on a nearby parallel corridor away from transit can help minimize bicyclist-pedestrian conflicts (2). It may also be beneficial to place separated bike lanes adjacent to rail corridors to encourage bicyclists to ride away from in-street rail tracks that may pose a hazard (2). Using landscaped barriers, such as “Oasis Greenways,” to separate bicycle and motor vehicle traffic provides several additional benefits compared to pavement markings including recreational areas, public health, and increased land value by removing lanes from roads with unneeded capacity and using that space for bike lanes, wide sidewalks, and planting strips (4). Design Issues Some drivers have expressed concern that installing separated bicycle lanes will potentially increase vehicular travel times (7). Solutions for implementing separated bicycle lanes should consider trade-offs associated with impacts on vehicular traffic flow while providing the protection to bicycles afforded by separation from traffic (7). Separated bike lanes may create a false sense of security that encourages bicyclists to behave less cautiously than they would on a shared use lane (5). Cross References Shared Bus-Bicycle Lanes 29-14, Bicycle Lanes 29-6, Contraflow Bicycle Lanes 29-10, Markings for Bicycles at Intersections 29-4 References 1. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY. 2. Dickman, D., Falbo, N., Durrant, S., Gilpin, J., Gastaldi, G., Chesston, C., . . . Pressly, R. (2016). Small town and rural multimodal networks. Washington, DC: Federal Highway Administration. 3. Federal Highway Administration. (2012). Manual on uniform traffic control devices for streets and highways. 2009 edition with revision numbers 1 and 2 incorporated. Washington, DC. 4. Bertulis, T. and Furth, P. (2014). Oasis Greenways: a New Model of Urban Park and Bikeway Within Constrained Street Rights-of-Way. TRB 93rd Annual Meeting Compendium of Papers. Transportation Research Board, Washington, DC. 5. DuBose, B., Lasky, M. E., and Sallaberry, M. J. (2013). Separated bikeways. Washington, DC: Institute of Transportation Engineers. 6. Wang, J., and Lindsey, G. (2017). Equity of Bikeway Distribution in Minneapolis, Minnesota. Transportation Research Record: Journal of the Transportation Research Board, No. 2605, pp. 18–31. 7. Burke, C. M., and Scott, D. M. (2017). TRB 96th Annual Meeting Compendium of Papers. Transportation Research Board, Washington, DC.

HFG BICYCLISTS VERSION 2.1 29-10 CONTRAFLOW BICYCLE LANES Introduction Contraflow bicycle lanes refers to bicycle lanes installed on the left side of a one-way street to give bicyclists the option to ride opposite the flow of traffic in a designated bike lane. Contraflow bike lanes may be considered in situations where travel in a with-flow bike lane would result in substantial out-of-direction travel and can be installed around high bicycle use destinations to provide more direct access (1). This guideline discusses methods for maximizing bicyclist safety and reducing potential traffic conflicts when designing contraflow bicycle lanes. Design Guidelines Contraflow Bike Lanes  Bicycle lane word, symbol, and arrow markings should follow the MUTCD figure 9C-3 (2) and define the bike lane direction so that the portion of the street is designated for preferential use by bicyclists (3).  When configured without parking, a solid double yellow lane line should be used to separate opposing motor vehicle lanes from the contraflow bike lane (3).  If sufficient space exists, a buffered bike lane should be used with the contraflow lane markings. A broken buffer may be used if there is on-street parking present (3). See the Bicycle Lanes guidelines on page 29-6 for guidance on designing buffered bike lanes.  If there is room, bike lanes should be used on both sides of the motor vehicle lanes. If there is not enough room for a dedicated with-flow bike lane, shared lane markings should be used to guide with-flow bicyclists toward the right side of the road (3). See the Shared Use Lanes guidelines on page 29-12 for guidance on designing shared use lanes.  Contraflow bike lane markings should be extended across intersections to alert cross street traffic to look for contraflow bicyclists (3).  Bike lane symbols and directional arrows should be used on both the approach and departure of each intersection to remind bicyclists to use the bike lane in the appropriate direction and to remind motorists to expect two-way bicycle traffic (1).  At traffic signals, signal heads should be provided for contraflow bicyclists. Adding a supplemental plaque that reads, “BICYCLE SIGNAL,” may be needed to clarify the signal head’s purpose (1).  A contraflow bike lane design should be used where there are few intersecting driveways and streets to minimize conflicts between cross traffic that may not be expecting two-way bicycle traffic (1). The figure below is an example of a contraflow bicycle lane design from NACTO (3). A dedicated bike lane is used for with-flow bicycle traffic. If there is less road width available, the dedicated bike lane and adjacent motor traffic lane could be combined into a shared use lane. A contraflow bike lane with the MUTCD bicycle lane markings and a solid double yellow lane line separating contraflow bicycle and motor vehicle traffic. Contraflow Bicycle Lane Design Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-11 Discussion Contraflow bike lanes are designed to allow bicyclists to ride in the opposite direction of motor vehicle traffic and are used to create a two-way bicycle street on a one-way motor traffic street (3). Contraflow bike lanes separate traffic using yellow center lane striping or a buffer (3) and are generally recommended in areas with numerous one-way streets or where following traffic flow would result in difficulty for bicyclists (4). Separating contraflow bike lanes from motor vehicle traffic with a double solid yellow line indicates to motor vehicles that there is opposing bicycle traffic on the other side of the line and no passing is allowed to the left of the double solid yellow line (1, 3). In areas with higher speeds or traffic volumes, installation of buffers, medians, or traffic separators between the contraflow bike lane and the adjacent motor traffic lane should be considered to provide more separation between motorists and bicyclists traveling in opposing directions (1, 3). While yellow center lane striping can alert adjacent motor traffic to the presence of a contraflow bike lane, cross traffic entering one-way streets may not expect these contraflow bicyclists. Extending contraflow bike lane markings across intersections can alert cross traffic to look for contraflow bicyclists and be aware of their presence (3). Contraflow bike lanes can be installed on streets where large numbers of bicyclists are already riding the opposite direction of motor vehicle traffic, on corridors where alternative routes lead to excessive out-of-direction travel or where the alternative route is through unsafe streets with high traffic volumes and/or no bicycle facilities, on streets where the contraflow lane would provide direct access to popular destinations, and preferably on low-speed, low-volume streets (3). Contraflow bike lanes can provide connectivity and access to bicyclists traveling in both directions; reduce dangerous wrong-way riding and sidewalk riding; decrease trip distance, number of intersections encountered, and travel times; and allow bicyclists to use safer, less trafficked streets (3). See the Bicycle Lanes guideline on page 29-6 for information about designing left side bicycle lanes that travel with the flow of traffic. Design Issues Where parking is present along a contraflow bike lane, motorists leaving a parking space may have difficulty seeing bicyclists in the contraflow bike lane, as sight lines may be blocked by other parked vehicles. Therefore, the design of contraflow bike lanes is discouraged where parking is present on the same side of the street (1). Cross References Markings for Bicycles at Intersections, 29-4 Bicycle Lanes 29-6 Shared Use Lanes 29-12 References 1. American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition. 2. Federal Highway Administration. (2012). Manual on uniform traffic control devices for streets and highways. 2009 edition with revision numbers 1 and 2 incorporated. Washington, DC. 3. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY. 4. Raborn, C., Torbic, D. J., Gilmore, D. K., Thomas, L. J., Hutton, J. M., Pfefer, R., . . . Hardy, K. K. (2008). NCHRP Report 500: Guidance for Implementation of the AASHTO Strategic Highway Safety Plan, Volume 18: A Guide for Reducing Collisions Involving Bicycles. Transportation Research Board, Washington, DC.

HFG BICYCLISTS VERSION 2.1 29-12 SHARED USE LANES Introduction Shared use lanes are lanes on the roadway that are designated for mixed use between bicyclists and motorists. Shared lane markings, also known as sharrows, are markings used to indicate the shared lane environment and promote proper bicyclist positioning. When shared use lanes are supplemented with shared lane markings, bicycle traffic on the street is legitimized and motor vehicle drivers are alerted to the potential presence of bicyclists without requiring additional street space (1). This guideline discusses methods for maximizing safety and reducing potential traffic impacts when designing shared use bike lanes. Design Guidelines Shared Use Lanes  Where possible, lane widths that are 14 ft (4.3 m) or greater are recommended to allow motorists to pass bicyclists without encroaching into the adjacent lane (2).  Use a “Share the Road” sign assembly (W11-1 + W16-1P (3)) at the end of dedicated bicycle lanes and/or at the beginning of a shared use lane to alert motorists and bicyclists that they will be sharing the road (2).  Post a “BICYCLES MAY USE FULL LANE” sign (R4-11, (3)) at the beginning of roads that are too narrow for bicyclists and motorists to ride side-by-side within the shared use lane (2). Shared Lane Markings  On roads with on-street parallel parking, shared lane markings should be placed at least 11 ft (3.4 m) from the curb face, or edge of the traveled way where there is no curb. For roads without on-street parallel parking, shared lane markings should be placed at least 4 ft (1.2 m) from the road’s edge (1, 2).  Shared lane markings can be placed farther towards the center of the lane than the minimum distances above, such as in cases where the lane is too narrow for side-by-side operation of a bicycle and a motor vehicle (2).  Consider using bicycle priority lane markings to encourage cyclists to ride farther from parked cars (i.e., outside of the ‘door zone’) and in the priority zone. Using priority lane markings encourages cyclists to ride in the priority zone rather than on the sidewalk (4). Examples of priority lane markings include super-sharrow markings (a continuous band of green in conjunction with shared lane markings) and sharrow markings between dashed lines (5, 6). The figure at left shows the typical placement of shared lane markings (sharrows). The sharrow marking placements reflect minimum distances from the curb, however, sharrows should be placed in the center of the lane if there is not enough room for side-by-side riding (2). Note that the MUTCD guidance used for shared lane marking placement assumes an 8 ft wide parking lane (3). Source: adapted from AASHTO (2) Shared Lane Marking Placement Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-13 Discussion Shared Use Lanes: Shared use lanes can be used on bicycle boulevards, traffic calmed streets with a designed speed of less than 25 mph, on downhill segments (if space does not permit a wide downhill bike lane), within single or multilane roundabouts, along front-in angled parking, and where street widths can only accommodate a dedicated bicycle lane in one direction (2). Using shared use lanes on roads with narrow lane widths may increase bicyclist lateral distance to the curb, increase lateral separation between vehicles and bicycles, reduce vehicle encroachment to the adjacent inside lane when passing bicycles, and reduce wrong-way riding (7, 8). Shared Lane Markings: Shared lane markings indicate a shared lane environment for bicycles and motor vehicles and are painted at an alignment that represents a practical path for bicycle travel (2). Shared lane markings should be placed in the center of the usable lane unless it is possible for bicyclists and motorists to share the lane safely side-by-side (9). Implementing shared use lane markings alerts motor vehicle drivers to the potential presence of bicyclists, alerts road users of the lateral position bicyclists are expected to occupy within the travel lane, advertises the presence of bikeway routes to all users, provides a wayfinding element along bike routes, keeps bicyclists out of the ‘door zone,’ encourages safe passing by motorists, and reduces wrong-way bicycling while requiring no additional street space (2). Design Issues From the perspective of both safety and reducing potential traffic impacts, designated bicycle lanes are preferred over shared use lanes when the road is sufficiently wide enough to accommodate bicycle lanes (9, 10, 11). Cross References Markings for Bicycles at Intersections, 29-4 Bicycle Lanes, 29-6 Shared Bike/Bus Lanes, 29-14 References 1. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York. 2 American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition. 3. Federal Highway Administration. (2012). Manual on uniform traffic control devices for streets and highways. 2009 edition with revision numbers 1 and 2 incorporated. Washington, DC. 4. Kassim, A., Ismail, K., and Woo, S. (2017). Investigation of the Effect of Super-Sharrows on Cyclist and Vehicle Behavior. Transportation Research Record: Journal of the Transportation Research Board, No. 2659, pp. 224-232. 5. Foletta, N., Nielson, C., Patton, J., Parks, J., and Rees, R. (2015). Green Shared Lane Markings on Urban Arterial in Oakland, California: Evaluation of Super Sharrows. Transportation Research Record: Journal of the Transportation Research Board, No. 2492, pp. 61–68. 6. Furth, P. G., and D. M. Dulaski. (2011). More Than Sharrows: Lane-Within-a-Lane Bicycle Priority Treatments in Three U.S. Cities. TRB 90th Annual Meeting Compendium of Papers. Transportation Research Board, Washington, DC. 7. Sando, T. (2014). Operational analysis of shared lane markings and green bike lanes on roadways with speeds greater than 35 mph. Jacksonville, FL: University of North Florida. 8. Raborn, C., Torbic, D. J., Gilmore, D. K., Thomas, L. J., Hutton, J. M., Pfefer, R., . . . Hardy, K. K. (2008). NCHRP Report 500: Guidance for Implementation of the AASHTO Strategic Highway Safety Plan, Volume 18: A Guide for Reducing Collisions Involving Bicycles. Transportation Research Board, Washington, DC. 9. Brady, J. F., Mills, A. F., Loskorn, J. A., Duthie, J. C., and Machemehl, R. B. (2010). Effects of shared lane markings on bicyclist and motorist behavior along multi-lane facilities. Paper presented at the Annual Conference of the Canadian Society for Civil Engineering, CSCE 2010. 10. Hourdos, J., Lehrke, D., Duhn, M., Ermagun, A., Singer-Berk, L., and Lindsey, G. (2017). Traffic impacts of bicycle facilities. Minneapolis, MN: University of Minnesota. Retrieved from http://dot.state.mn.us/research/reports/2017/201723.pdf 11. Love, D. C., Breaud, A., Burns, S., Margulies, J., Romano, M., and Lawrence, R. (2012). Is the three-foot bicycle passing law working in Baltimore, Maryland? Accident Analysis & Prevention, 48, pp. 451-456.

HFG BICYCLISTS VERSION 2.1 29-14 SHARED BUS-BICYCLE LANES Introduction Shared Bus-Bicycle Lanes refers to dedicated lanes with right-of-way restricted to the use of buses, bicycles, and sometimes right-turning vehicles. Increasingly, cities across the U.S. are implementing these lanes to improve multimodal mobility. Safety implications associated with shared bus-bicycle lanes are related to disparities in travel speeds and vehicle sizes between buses and bicycles, shared lane width, bicycle visibility, and interactions between buses and bikes, particularly at and around bus stops. This guideline provides recommendations for designing bus- bicycle shared lanes that can help mitigate these safety challenges. Design Guidelines  Pavement markings must indicate that the lane is dedicated to transit, including a solid white line and “BIKE BUS ONLY” or similar marking (1).  Install signs permitting buses and bicycles, and excluding other traffic. “BUSES-BIKES ONLY” signs may be used. Overhead signs are preferred (1).  Buses must operate on the right side of the lane and pull to the curb at stops when possible. Coordination with transit operator instruction is key to the success of a bus-bike lane (1).  Recommended width of a full-time bus-bike lane is 10–11 feet for offset lanes, and up to 12 feet for curbside lanes (1).  Lanes 13–15 feet wide should be avoided in most cases to limit unsafe passing movements (1).  If 15–16 feet of width is available, consider providing a marked conventional bike lane on the left or right side of the bus lane, marked and signed as a green-colored bicycle lane to enhance visibility (1, 2).  If 13–14 feet of width is available, a marked buffer can be added on the left side of the bus-bike lane so that buses are guided to the right, allowing any passing bicycle traffic to use the buffer area at stops (1).  Consider installing dedicated bike lanes or separated bike lanes at bus stops to minimize interactions between buses and bicycles (1). The figure below shows suggested lane widths and possible configurations for shared bus-bicycle lanes (1). Suggested Lane Widths for Shared Bus-Bicycle Lanes Source: NACTO (1) Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-15 Discussion Shared bus-bicycle lanes (SBBLs) are lanes dedicated for use by both buses and bicyclists and often, right-turning vehicles at intersections (3). SBBLs provide a time advantage to buses by prioritizing their travel over other vehicular traffic, while also providing bicyclist protection from mixed traffic (3), and reduce the impact of general traffic on both buses and bicycles when insufficient roadway space is available to provide separate exclusive facilities for the two modes (1, 4). For both modes of travel, however, SBBLs are low-comfort solutions because buses and bicyclists compete for the same space near the curb, often with limited lane width and close proximity when passing each other (1). Separate dedicated bus and bicycle lanes are preferred over SBBLs, particularly on high-volume bus routes during peak traffic times (1). Lane width is an important consideration when designing SBBLs. Because buses tend to overtake bicyclists on the road, adequate lane widths are necessary for the bus to pass without encroaching on the adjacent vehicle lane (1). Although wider shared lanes provide bicyclists with more space during bus overtaking maneuvers, they also result in higher overtaking speeds by buses (5). Even when not being overtaken, bicyclists in the study by De Ceunynck et al. had significantly higher riding speeds at narrower roads if they knew a bus was behind them, indicating a level of discomfort for bicyclists in these situations. There are several other issues created by SBBLs that must be considered when designing shared lanes. Bicyclists approaching a stopped bus at a bus stop often pass the bus to avoid stopping themselves (6). Because bicycles are typically much slower than buses, the bus will generally overtake and pass the bicyclist after leaving the bus stop (6). This “leapfrogging” between buses and bicycles heightens the risk to bicyclists by increasing the number of interactions between the vehicles. Countermeasures to minimize “leapfrogging” and provide sufficient lane width for safe passing are recommended where feasible. Another potential conflict is when a bus pulls forward from a bus stop at the same time that a bicyclist attempts to overtake the previously stopped bus (1). Separating a bike lane from the SBBL at bus stops can minimize bus-bicycle interactions by providing bicyclists a way to safely pass buses while passengers are boarding and disembarking the bus and for buses to safely pass bicyclists upon leaving the bus stop (1). Right and left hook crashes may also occur when buses turn right or left while a bicycle is passing in the blind spot (1). Bike lane markings straight through intersections can raise awareness for bicyclists and motorists for potential conflict areas, reinforce bicyclist priority over vehicles that are turning, make bicycle movements more predictable, and increase the visibility of bicyclists (2). Design Issues Shared bus and bicycle lanes will not provide the same level of benefit as other bus lane types, particularly when right turns need to be accommodated at intersections, and there will typically be some degree of illegal driving, parking, or stopping activity in the lane despite active enforcement efforts (4). Roadways with significant uphill grades are not good candidates for SBBLs because the speed differential between bicycles and buses is considerably greater compared to level or downhill roadway sections (4). Roadways with a high volume of oncoming traffic in the adjacent lane are also not good candidates for SBBLs since buses would frequently have to slow behind bicyclists while waiting for a gap in traffic to move around the bicyclist (4). Current road design guidelines assume that bicyclists take up a width of one meter, however observations collected by De Ceunynck et al. showed that bicyclists may take up much less space while being overtaken. Cross References Markings for Bicycles at Intersections, 29-4 Bicycle Lanes, 29-6 Mitigating Heavy Vehicle Conflicts with Bicycles, 29-16 References 1. National Association of City Transportation Officials (NACTO). (2016). Transit Street Design Guide. Island, Press. 2. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY. 3. Hillsman, E. L., Hendricks, S. J., and Fiebe, J. (2012). A summary of design, policies and operational characteristics for shared bicycle/bus lanes. Tampa, FL: University of South Florida. 4. Ryus, P., K. Laustsen, K. Blume, S. Beaird, and S. Langdon. (2016). TCRP Report 183: A Guidebook on Transit-Supportive Roadway Strategies. Transportation Research Board, Washington, DC. 5. De Ceunynck, T., Dorleman, B., Daniels, S., Laureshyn, A., Brijs, T., Hermans, E., and Wets, G. (2017). Sharing Is (S)caring? Interactions between Buses and Bicyclists on Bus Lanes Shared with Bicyclists. Transportation Research Part F: Traffic Psychology and Behaviour, 46, Part B, pp. 301-315. 6. American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition.

HFG BICYCLISTS VERSION 2.1 29-16 MITIGATING HEAVY VEHICLE CONFLICTS WITH BICYCLES Introduction The difference in mass and size between heavy vehicles and bicycles can contribute to serious bicyclist injuries or fatalities when conflicts between these two modes of travel occur. Heavy vehicle blind zones and reliance on mirrors for visibility make it difficult for heavy vehicle operators to observe bicyclists riding close to the vehicle, while bicyclists are often unaware of these visibility challenges and ride too close to the truck or engage in unsafe maneuvers. This guideline provides recommendations for road designs that help to mitigate heavy vehicle conflicts with bicycles. Design Guidelines  Consider including a buffered bike lane on roadways with a high percentage of heavy vehicle use to provide separation between trucks and bicycles, particularly when the bike lane is adjacent to a parking lane (1, 2).  Avoid roadway features, such as green infrastructure, that obstruct the view of the intersection (3, 4).  Reduced speed limits at intersections and road segments with high bicycle and heavy vehicle traffic volumes (1).  Sufficient parking for commercial vehicles should be considered when implementing bike lanes to minimize the incidence of trucks parking in the bike lane when making deliveries (5).  At intersections, place bike lanes closer to the vehicle lane (Richter and Sachs (3) suggest no more than 0.5 m) to maximize the visibility in the truck’s right-hand mirror and to avoid occluded views caused by landscaping, parked cars, and other obstructions.  At intersections, consider placing a bicycle box or stop line ahead of the vehicle stop line to make bicycles more visible and conspicuous (4).  Consider installing separate signals for bicycles at intersections with heavy truck traffic volumes and provide advance green timing for bicycles to allow bicycles extra time to cross the intersection and increase their conspicuity (3). RECOMMENDED LANE WIDTHS FOR URBAN AND SUBURBAN TWO-LANE UNDIVIDED ROADWAYS WITH ON-STREET PARKING AND CONSTRAINED ROADWAY WIDTHS (6 ) . Widths (ft)—One direction of travel Curb to Curb (ft) Roadway conditions1 Parking Lane Buffer Bike Lane Buffer Travel Lane Curb to CL 8 3* 4 2 10 27 54 All conditions 7 3* 4 2 10 26 52 All conditions 7 2* 4 2 10 25 50 High volume or high truck percentage 7 3 5 0 10 25 50 Low volume and low truck percentage 7 1.5 4 1.5 10 24 48 High volume or high truck percentage 7 3 4 0 10 24 48 Low volume and low truck percentage 7 2 5 0 10 24 48 Low volume and low truck percentage 7 2 4 0 10 23 46 All conditions 7 0 5 0 10 22 44 All conditions 7 1** 4 0 10 22 44 All conditions * May consider combining buffers to create a 4-ft buffer between parking and bike lanes. ** Caution that striping of double white lines may cause confusion. 1 The suggested threshold for distinguishing between low and high traffic volume is 20,000 vpd, and the suggested threshold for distinguishing between low and high truck percentage is 10 percent trucks in the vehicle mix. Based Primarily on Expert Judgment Based Equally on Expert Judgment and Empirical Data Based Primarily on Empirical Data

HFG BICYCLISTS VERSION 2.1 29-17 Discussion Heavy vehicle-bicycle crashes in urban settings were generally found to occur in locations with higher employment shares in freight-dependent industries (e.g., wholesale, transportation, warehousing, and retail) (5). A study conducted in Beijing suggests that using a median division between the roadway and bikeway to help reduce crashes in areas like the freight-dependent commercial sections of cities (1). Of all heavy vehicle-bicycle lane violations, about 81 percent were in standard lanes, while only 7 percent were in protected lanes or curbside lanes (5). Torbic et al. found that bicyclists positioned themselves approximately 2.5 to 3.0 ft closer to parked vehicles or the curb when in the presence of a higher proportion of heavy vehicles. As such, on streets with truck percentages above 10 percent, additional displacement of bicyclists due to trucks should be considered when determining the allocation of street width between parking lanes, bicycle lanes, and travel lanes (2). In particular, consideration should be given to designating additional street width to bicyclists and/or providing a buffer to account for the additional displacement of bicyclists at higher truck percentages (2). Akhtar et al. recommend using an overtaking clearance of at least 1.5 m., citing an incident in which a truck driver tried to overtake bicyclists with just 0.5 m of clearance and struck one of the cyclists with the trailer (7). In most situations where a bicycle lane is adjacent to on-street parking, Fees et al. recommend an 8 ft. width for the parking lane. An 8-ft parking lane provides sufficient space for a large percentage of heavy vehicles to park within the limits of the parking lane, and it allows more of the roadway cross section to be designated for bicyclists in the bicycle lane and motor vehicles in the travel lanes (6, 8). A rather small distance between the bicycle and vehicle lanes at intersections should be preferred because of the increasing obstructive view created when increasing the distance between vehicle lanes (3). This problem can be seen in left and right hook crashes (3). Bike lane markings straight through intersections can raise awareness for bicyclists and motorists for potential conflict areas, reinforce bicyclist priority over vehicles that are turning, make bicycle movements more predictable, and increase the visibility of bicyclists (4). Other visibility countermeasures for bicycles such as the installation of bike boxes ahead of traffic at intersections are discussed further in Markings for Bicycles at Intersections (see page 29-4). Countermeasures for designing bicycle signals and adjusting signal timing for bicycles can be found in Signals and Signal Timing for Bicycles at Intersections (see page 29-2). Design Issues The addition of bicycle lanes on local roads that serve as commercial vehicle delivery routes can have a negative impact on bicycle safety because of commercial vehicle parking while making deliveries. Commercial vehicle drivers have been found to park their trucks on bicycle lanes while making their deliveries, requiring bicyclists to exit the bike lane and merge into traffic (5), increasing their exposure to hazards. Designs that accommodate commercial vehicle parking in such areas are preferable whenever possible. Cross References Markings for Bicycles at Intersections, 29-4 Signals and Signal Timing for Bicycles at Intersections, 29-2 Bicycle Lanes, 29-6 Separated Bicycle Lanes, 29-8 Heuristics for Selecting the Yellow Timing Interval, 11-6 References 1. Yan, X., Ma, M., Huang, H., Abdel-Aty, M., and Wu, C. (2011). Motor vehicle-bicycle crashes in Beijing: Irregular maneuvers, crash patterns, and injury severity. Accident Analysis & Prevention, 43(5), pp. 1751-1758. 2. Torbic, D. J., Bauer, K. M., Fees, C. A., Harwood, D. W., Van Houten, R., LaPlante, J., and Roseberry, N. (2014). NCHRP Report 766: Recommended Bicycle Lane Widths For Various Roadway Characteristics. Transportation Research Board of the National Academies, Washington, DC. 3. Richter, T., Sachs, J.-C., Swedish National, R., & Transport Research, I. (2016). Turning accidents between vehicles and cyclists driving straight ahead. Paper presented at the Road safety on five continents (RS5C): 17th international conference, Rio de Janeiro, Brazil. 4. National Association of City Transportation Officials. (2014). NACTO urban bikeway design guide (2nd ed.). New York, NY. 5. Conway, A., Tavernier, N., Leal-Tavares, V., Gharamani, N., Chauvet, L., Chiu, M., and Yeap, X. B. (2016). Freight in a Bicycle-Friendly City: Exploratory Analysis with New York City Open Data. Transportation Research Record: Journal of the Transportation Research Board, No. 2547, pp. 91–101. 6. Fees, C. A., Torbic, D. J., Bauer, K. M., Van Houten, R., Roseberry, N., and LaPlante, J. (2015). Design Guidance for Bicycle Lane Widths. Transportation Research Record: Journal of the Transportation Research Board, No. 2520, pp. 78–89. 7. Akhtar, J., Aust, M. L., Eriksson, R. J., Fagerlind, H., Hoye, A., Phillips, R. O., and Sagberg, F. (2010). Factors contributing to road fatalities: Analysis of in-depth investigation data from passenger car intersection crashes and from collisions between bicycles and motorized vehicles (Report No. 1067/2010). 8. American Association of State Highway Transportation Officials. (2012). Guide for the development of bicycle facilities, fourth edition..

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In 2015, there were more than 6 million police-reported crashes in the United States. While crashes are complex and it is generally interactions between road users, vehicles, and the environment that lead to crashes, some form of driver error is a contributing factor in most crashes.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 316: Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New Chapters is an addendum to NCHRP Report 600: Human Factors Guidelines for Road Systems (HFG),Second Edition, which was the first complete holistic release of the HFG.

Supplemental to the document is a flier describing the updated and new chapters and NCHRP Web-Only Document 316: Human Factors Guidelines for Road Systems 2021 Update,Volume 2: Conduct of Research Report.

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