Design Controls for Bicycle Facilities

Motor vehicle volumes and speeds are not fixed. They can be changed through policy and design, resulting in safer streets for all users. Implementing bikeways will increase the comfort of people on bikes and improve safety for all users.

In some cases, a bicycle facility may fall short of the AA&A criteria but can still substantially reduce traffic stress for people on bikes. Jurisdictions should not use the inability to meet the AA&A criteria to avoid implementing a bikeway and should not prohibit the construction of facilities that do not meet the criteria.

Design User

To achieve growth in bicycling, bikeway design should meet the needs of a broad set of people who would potentially bike. When selecting a bikeway design strategy, identify potential design users based on network goals and the potential to broaden the base of people who might bike on a specific street.

A typical bikeway should appeal to current and potential users, favoring those who need low-stress bikeways, such as protected bike lanes or bike boulevards, to be safe and confident while biking. Personal safety concerns should be considered in bikeway design, resulting in well-lit, connected routes that attract more users.

For AA&A bikeways, pay additional attention to the needs of younger and older users, including differences in the ability to detect risks, visual acuity, and physical strength.

All Ages & Abilities Bikeways

Community conversations and Bike Network Plans should be oriented toward an AA&A bike facility that will serve the broadest range of people. Bikeways should be selected based on local conditions, including street design, motor vehicle speeds and volumes, transit use, adjacent land use, and curbside demand.

Protected bike lanes are the only type of AA&A bikeway tool permissible for AA&A streets with high curbside demand, speeds of more than 25 mph (40 km/h), multiple adjacent general-purpose travel lanes, and streets with volumes above 6,000 vehicles per day.

Not every segment of a bike network must have a protected bike lane. Where motor vehicle speeds and volumes are strictly managed, designers can draw on a range of bikeway types. The number of adjacent general travel lanes for these bikeways must not exceed one at the midblock. Additional lanes may be added at signalized intersections as necessary for safety and where the bikeway is designed through the intersection. (See Design Strategies for Signalized Intersections.)

Design Vehicle

Design for the most vulnerable street user rather than the largest possible vehicle. While designs must account for the challenges that larger vehicles, especially emergency vehicles, may face, these challenges must not override the safety or comfort of all other users. Assume that emergency vehicles can use the full right-of-way in both directions.

For most urban streets, the largest design vehicle should be a single-unit truck (SU-30) with a turning radius of 42 ft (12.6 m). Lane widths of 10 ft (3 m) are appropriate and positively impact a street’s safety without impacting traffic operations.¹

On streets that serve transit or have more than 10% heavy vehicle traffic, lane widths of 11 ft (3.3 m) may be used. While the SU-30 should remain the design vehicle on these streets, a WB-50 control vehicle may be used at relevant intersections.

Increases in bikeway width or buffers, even of less than a foot, are noticeable to users and can provide significant benefits, while the same space assigned to a motor vehicle lane is often unnoticeable or even counterproductive.

Bikeway Design Vehicle

Bikeway use is growing in tandem with the diversity of devices, in size and speed, being used. This growth requires new thinking about street and bikeway design. When designing bikeways, the most common devices fit into one of four operational categories:

• Mini devices: Electric and non-electric scooters, skateboards, rollerblades, and other devices under 20 in (50 cm) wide that are typically used while a person is standing upright
• Typical bikes: Electric and conventional upright bikes and tricycles, as well as recumbent bikes, hand cycles, and any wheeled devices up to 2.5 ft (0.8 m) wide
• Cargo bikes: Electric and conventional bikes and tricycles between 2.5-3 ft (0.8-0.9 m) wide that have an extended wheelbase or that are pulling a trailer
• Extra-large bikes: large freight tricycles, pedicabs, and other devices between 3 ft (0.9 m) and typically up to 4.5 ft (1.4 m) wide

Devices from all of these categories should be expected in any bikeway. Designers should provide appropriate width and turning space for the longest and widest device possible.

Rideable Width

In shared environments, such as bike boulevards, the total curb-to-curb width is available for people on bikes and other micromobility devices, subtracting any space allocated to parking or curb extensions. However, all other bikeways dedicate a specific width to these activities. 

As bikeway use grows and people use a more diverse mix of devices and a wider variety of speeds, bikeways need to be sized to meet new operating needs, such as platooning, riding side-by-side, and passing. Wider bikeways can comfortably accommodate more users. Wide protected bike lanes are valuable for children and caregivers, side-by-side riders, people using adaptive devices, and people moving goods.

Design bikeways to have enough rideable width for all expected users to operate comfortably, ride side-by-side, or pass one another. Rideable width is the usable width of a bikeway for riding, excluding any shy distance or unrideable areas. Rideable width can extend beyond the marked bikeway to include parts of the buffer at the same level as the bikeway.

The shy distance for bikeways is the unrideable surface next to a vertical object, such as a curb, barrier, streetlight, or sign pole. 

• Gutter pans are not rideable and have a shy distance of 1-2 in (2-5 cm).
• For beveled curbs, the shy distance is 6 in (15 cm).
• For low curbs under 6 in (15 cm) tall, the shy distance is 8 in (20 cm).
• For vertical curbs that are 6 in (15 cm) tall, the shy distance is 10 in (25 cm).
• Barriers that are over 2 ft (0.6 m) high have a shy distance of 20 in (50 cm).

In many cities, the rideable width also accommodates maintenance vehicles necessary for sweeping, snow plowing, and snow removal. Maintenance vehicles designed to sweep or clear snow range in widths from 4 ft (1.2m) to over 8 ft (2.4 m). Cities relying on these vehicles for maintenance needs typically have a minimum clear distance of 7-8ft (2.1-2.4 m) on protected bike lanes.

Rideable widths do not include the shy distance to vertical objects adjacent to the bike lane. Preferred rideable widths allow for both passing space and riding space without having any overlapping space.

Turn Radii

Turning radii at intersections need to be maneuverable by all devices operating in the bikeway. People on e-scooters may find it challenging to turn safely at their minimum turn radius. Cargo and tandem bikes have particularly wide turn radii. Cargo bikes have a minimum inner turn radius of 5 feet (1.5 meters) and a sweeping radius of at least 9 feet (2.7 meters). Tandem bikes have an inner radius of 7.5 feet (2.3 meters) and a sweeping radius of at least 10.5 feet (3.2 meters).² If possible, the inside radius of horizontal curves should be at least 10 feet (3 meters) to accommodate typical bikes and wider-turning devices at low speeds.^3,4

Design Speed

Speed plays a critical role in the likelihood and severity of crashes. There is a direct correlation between speed, crash risk, and the severity of injuries. Design streets using target speed (the speed you intend for drivers to go) rather than operating speed. Bring the design speed in-line with the target speed by implementing measures to reduce and stabilize operating speeds as appropriate. Narrower lane widths, fewer general-purpose travel lanes, constructed traffic-calming devices, and the addition of dedicated bikeways reduce traffic speeds and improve the quality of the bicycle and pedestrian realm.

Bikeway Design Speed

While e-bikes and conventional bikes can have similar speeds, observed operating speeds for e-bikes are typically higher and spread over a smaller range than conventional bikes. Urban e-bike operating speeds are typically 12-18 mph (19-29 km/h), while conventional bike speeds range from about 4-18 mph (4-29 km/h).^5,6 Electric options for mini devices are typically limited to 8-15 mph (13-24 km/h).

In bike boulevards, advisory bike lanes, constrained bike lanes, protected bike lanes, and shared-use paths, the typical design speed for people riding bikes can be assumed to be 10-15 mph (16-24 km/h), although signal progression, operating width, and platooning will reduce overall operating speeds. On shared-use paths or bike paths with low volumes of pedestrians, people on bikes or other mobility devices may travel at speeds of 20 mph (32 km/h) or more, though slower users should be expected.

When designing bikeways, keep in mind the design user; they may be people traveling at the lower end of typical speeds. Do not assume confident people on bikes will set the pace for all others. Speed differentials may also require different design strategies when considering downhill and uphill needs.

1. “…this study found no evidence that narrower lanes are associated with the higher number of crashes and that narrow lanes (9-foot and 10-foot) increase the risk of vehicle accidents, after controlling for cross-sectional street design characteristics and other confounding variables. Quite contrary, our models confirm that in some cases (in the speed class of 30–35 mph), narrowing travel lanes is associated with significantly lower numbers of non-intersection traffic crashes and could actually contribute to improvement in safety.”
   Hamidi, S, and R. Ewing. A National Investigation on the Impacts of Lane Width on Traffic Safety. Johns Hopkins Bloomberg School of Public Health, November 2023: 3. https://narrowlanes.americanhealth.jhu.edu/report/JHU-2023-Narrowing-Travel-Lanes-Report.pdf.  ↩︎
2. Department for Transport. Cycle Infrastructure Design. Department for Transport, 2020. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/951074/cycle-infrastructure-design-ltn-1-20.pdf. ↩︎
3. Department for Transport. Cycle Infrastructure Design. Department for Transport, 2020. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/951074/cycle-infrastructure-design-ltn-1-20.pdf. ↩︎
4. American Association of State Highway and Transportation Officials. Guide for the Development of Bicycle Facilities, 4th Edition. AASHTO, 2012: Table 5-2, page: 5-14. https://epg.modot.org/files/9/97/641.1_Bicycle_Facilities_2021.pdf.  ↩︎
5. MacArthur, John. “Are e-bikes faster than conventional bicycles?” Portland State University Transportation Research and Education Center, November 2014. https://trec.pdx.edu/blog/are-e-bikes-faster-conventional-bicycles.  ↩︎
6. FHWA’s findings in extensive active and in-situ studies on trails found slightly higher and less widely distributed speeds for pedal-only bicycles, averaging 11 mph (17 km/h), with a 15th percentile of 7 mph (11 km/h) and an 85th percentile of 14 mph (22 km/h). 
   Federal Highway Administration. Characteristics of Emerging Road and Trail Users and Their Safety. Publication Number FHWA-HRT-04-103. USDOT, 2004: Table 12, page 74. https://www.fhwa.dot.gov/publications/research/safety/04103/index.cfm. ↩︎