Side boarding islands, like boarding bulbs, are dedicated waiting and boarding areas for passengers that streamline transit service and improve accessibility by enabling in-lane stops.
Side boarding islands are separated from the sidewalk by a bike channel, eliminating conflicts between transit vehicles and bikes at stops. For both streetcars and buses, boarding islands allow the creation of accessible in-lane stops with near-level or level boarding.
Green Lane Project
Application
Streets with moderate to high transit frequency, transit ridership, pedestrian volume, or bicycling volume can utilize boarding islands to maintain in-lane stops and provide separation to more users.
If bicycle facilities exist or are planned, island stops maintain continuity of the bike lanes.
If in-lane stops are desirable, especially adjacent to offset transit lanes, boarding islands can be accommodated in existing street width.
Platforms can be configured for level or near-level boarding.
If sidewalk width permits, boarding islands may be applied to streets with curbside transit operations and a bike facility.
Benefits
In-lane stop style reduces transit vehicle dwell times; on busy streets, in-lane stops may reduce stop delay between 5 and 20 seconds per location. Delay reductions are amplified as traffic congestion increases.1
Boarding islands eliminate bus-bike “leapfrogging” conflict at stops, in which buses merge across the bicycle travel path at stops, causing bicycles to merge into general traffic to pass the stopped bus, only to be passed again as the bus accelerates. At boarding islands, both buses and bicycles can move straight at the stop, in their own dedicated space.
Islands provide more space for transit passengers and amenities while maintaining a clear pedestrian path on the sidewalk. Operators are able to deploy ramps or bridge plates, as needed, onto the island without disrupting pedestrian flow.
Considerations
Boarding islands usually require less complex drainage modifications than boarding bulbs.
At high-volume stops, it may be necessary to require people on bikes to yield to people accessing the island directly from the sidewalk. Markings, color, and signage must reinforce appropriate yield behavior.
Lateral alignment with streetcars may require realignment of general traffic lanes or bike lane.
Bicycle signals can enhance the clarity of intersection movements. Consider using bike signals with far-side boarding islands to provide a dedicated bike and pedestrian through phase, especially if high turn volumes or a right-turn pocket is present. Bike signals are also applicable at near-side boarding islands where turns are prohibited and bicycles move concurrently with other through-traffic.
Critical
Boarding islands must be designed to permit accessible boarding. For low-floor vehicles using bridge plates, near-level boarding can usually be achieved with a 9.5- to 12-inch platform. Higher (14-inch) platforms typically require that all doors be configured for level boarding, and may be incompatible with some buses.
An accessible boarding area, typically 8 feet wide by 5 feet long, must be provided to permit boarding maneuvers by a person using a wheelchair (ADA Std. 810.2.2) (see Universal Design Elements).
Where the bike lane or cycle track requires bicyclists to yield at a crosswalk from the sidewalk onto the island, the BIKES YIELD TO PEDESTRIANS sign (MUTCD R9-6) and yield triangle markings must be installed.
Platform must be aligned to streetcar tracks with appropriate lateral clearance for level boarding; may require 9-foot moving lane or other track or lane realignment in cases with right-lane mixed-traffic operations.
Platform access ramp may have a maximum slope of 1:12 at a crosswalk or other crossing point, at the sidewalk and onto the platform (ADA Std. 405.2).
1Use reflective signage or other visible raised element on the leading (back left) corner of the island. KEEP LEFT or KEEP RIGHT (MUTCD R4-8) or object marker (OM-3) signs may be used.
Detectable warning strips must be placed on both sides of every crossing over the bike lane.
Recommended
2An accessible ramp should be placed at the intersection end of the island entering the crosswalk. If there is no crosswalk at the intersection, install one, with a refuge island tip to protect pedestrians (at least 6 feet wide).
For mid-block stops, include raised crosswalks across bike channel to encourage people on bikes to yield to people accessing the island.
3Boarding island stops should include shelters, seating, wayfinding, and passenger information when feasible.
4Shelters should be located at least 10 feet from crosswalks over the bike lane to allow visibility between people on bicycles and people exiting the island. Leaning rails may be located along this gap.
Optional
5Install leaning rails along the edge of the island along the bike channel on portions of the island without a shelter or accessible boarding area. If leaning rails or fence are installed along the accessible boarding area, the total island width usually must be increased to 9 feet. Boarding islands can be extended to include bike parking, additional seating, parklets, or other community facilities.
In locations with wide sidewalks and no parking, the bike lane or cycle track may be bent in to the sidewalk to create a boarding island. In this case, raised crossings are an option to encourage yielding to people accessing the island, and to reduce bicycle speeds at the stop. Bike lanes should not generally be bent into the sidewalk to create pull-out bus stops on streets with parking lanes.
A YIELD stencil marking may be marked in the bike channel prior to the crosswalk to reinforce the requirement to yield.
Near-side stop with bike channel at sidewalk level
1The boarding platform must at minimum span from the front door to the rear door, and may be extended to meet capacity demands.
2The bicycle lane behind the floating boarding island can be at street grade or may be raised. Where the bike lane changes grade, bicycle ramps should not exceed a 1:8 slope.2 If raised, delineate bike and pedestrian realms using colored paint or paving materials.
Bike lanes may be narrowed to slow bicycle traffic and reduce conflicts, with a minimum 5-foot width.
3Mark pedestrian crossings through bike lane. Yield teeth and other markings and signs such as YIELD stencils and BIKES YIELD TO PEDESTRIANS (MUTCD R9-6) signs inform bicyclists of the requirement to yield to pedestrians.
Where a near-side island is combined with a right-turn restriction, extend the refuge island into the intersection and reduce the curb radius to self-enforce the turn restriction and provide additional pedestrian space.
Continuing the bike lane in a protected configuration through the intersection simplifies interactions with pedestrians and provides right-turning vehicles with a place to wait as they approach the conflict zone.3
Portland Bureau of Transportation
Far-side stop with bike channel at street level
1If high turn volumes are present, include a rear storage area so cars are less likely to queue into the intersection while the bus dwells. More storage space may be necessary on streets with only one lane per direction.
2Accessible ramps should be paired with crosswalks to direct users to safe crossings. If the bike channel stays at street grade, ensure that ramps, landings, and detectable warnings are provided whenever pedestrians cross into another “modal zone” (i.e. bikeway or travel lane).
3At high passenger volumes, channelize pedestrian movements on and off the platform to reduce conflicts.
If a lean bar or railing is installed continuously along the back of the platform, the island must be at least 9 feet wide to accommodate the 8-foot deep accessible landing. If the accessible landing opens directly to an accessible crossing (either flush or raised), the island may be 8 feet wide.
A crossing over the bike channel may be raised to provide a flush path to the sidewalk. Install yield teeth and “YIELD TO PEDESTRIANS” signs. Bicycle ramps should not exceed a 1:8 slope.
Urban Bikeway Design Guide
Learn more about designing bike-friendly streets in NACTO’s Urban Bikeway Design Guide.
- On Dexter Avenue in Seattle, an important corridor through a rapidly growing neighborhood, side-boarding islands have been crucial to maintaining bus travel times. Average transit trip time through 1.5 mile segment has increased 0.4 seconds in three years post-implementation, during which time traffic volume increased 19% from 11,800 to 14,100 ADT. Bicycle ridership also increased 39% over the same period.
Chang, Dongho. Expanding Networks to Seattle’s Job Centers. Presentation, Seattle Department of Transportation: September 2015. ↩︎ - A slope between 1:10 and 1:25 is recommended by FHWA.
Goodman, Daniel, et al. Separated Bike Lane Planning and Design Guide. Federal Highway Administration, Washington, DC: 2015. ↩︎ - Rabito, Luciano, et al. Separated Bike Lane Planning & Design Guide. Massachusetts Department of Transportation, Boston, MA: 2015. ↩︎