Exclusive Bike Phases
Exclusive bike phases prohibit all motor vehicle movements during the bike phase, reducing delays for bike movements that would otherwise be multi-stage crossings.
Diagonal Bike Crossing
Use a diagonal bike crossing where a bikeway switches sides of the street or transitions from one-way on each side to two-way on one side. Diagonal bike crossings require bike signals and should include a diagonal crossbike. Consider informational signage for all street users, particularly when newly installed. This configuration does not require experimentation in the U.S.
Bike Scramble
A bike scramble provides time for bike movements from all directions simultaneously. Bike scrambles are most helpful at intersections with a high volume of bike turn movements, such as where two busy bikeways intersect. They are also used at intersections with high volumes of motor vehicle turns where providing multiple bike phases would have operational drawbacks.
A bike scramble may be combined with exclusive pedestrian movements if bikes proceeding on green are not in perpendicular conflict with dominant pedestrian movements, such as at protected intersections with adequate forward queuing areas and larger corner islands. People with disabilities, older adults, and those traveling with children may be challenged by the bike scramble as it can feel unpredictable. Always provide concurrent pedestrian phases during vehicular phases to provide other opportunities for people walking to cross.
Because bike scrambles provide a smaller percentage of the total signal cycle for bike movement, people on bikes may be delayed more than typical. Excessive bike delay can be avoided by minimizing cycle lengths or running the bike scramble phase multiple times per cycle to create both leading and lagging bike phases in both directions.
Bike signals are required. Consider informational signage for all street users, particularly when newly installed. This configuration requires experimentation in the U.S.
Protected Bike Phases
Protected bike signal phases eliminate motor vehicle conflicts with through movements for the bikeway. They are typically implemented only where it is possible to separate vehicular turns with turn lanes and signals.
Protected bike phases are easily understood and provide high-comfort crossings for people on bikes but occur only during a relatively short percentage of the signal cycle. Providing full protection usually involves longer bike wait times than a partially protected phase. Late-arriving bikes may face a red signal at intersections with lower-volume turns but not experience any turn conflict, leading to signal disregard.1
Protected Bike and Pedestrian Phases
People biking and walking in parallel paths share a protected phase. The bikeway has a green bike signal, and people walking are served with a Walk phase. Drivers continuing through the intersection see a green signal, but those turning face a solid red arrow signal. Bikeway users have a red bike signal during the turn phase.
Bike signals are required. This phasing may be applied to unidirectional or bidirectional bikeways. This configuration does not require experimentation in the U.S.
Exclusive Bike Phases with Concurrent Pedestrian Phases
At some intersections, exclusive bike movements are necessary, but the longer clearance time for pedestrians necessitates a pedestrian phase concurrent with vehicular traffic. The pedestrian phase begins before the vehicle movement and continues during the vehicle turn phase while bikes are stopped.
Bike signals are required. This phasing may be applied to unidirectional or bidirectional bikeways. Consider informational signage on the bikeway approach to inform users that they will face a red signal even while the pedestrian Walk phase is on. This configuration does not require experimentation in the U.S.
Partially Protected Bike Phases
Partially protected bike phasing allows vehicular through movements to start simultaneously to parallel bikeway movements. After a period of protected-only movement, bike movements continue, and drivers making turns see a green or flashing yellow arrow (FYA) turn phase.
Partially protected signal phasing can reduce the number of conflicts, even compared with full signal protection. They also provide more bike green time than a protected bike signal phase, reducing excessive delays and improving compliance. People biking and driving typically respond positively to surveys on this phasing strategy.
Partially protected bike phases are practical solutions in urban environments. They can be used where adding turn lanes and phases are unnecessary, such as where the right-of-way is constrained, where policies prioritize the right-of-way for non-vehicular uses, and where signal cycles are too short to accommodate an additional phase for turning vehicles.
Credit: Chicago Department of Transportation
Leading Bike and Pedestrian Intervals
Leading Bike Intervals (LBI) give people on bikes a head start at signalized intersections without a turn lane or phase for the conflicting vehicular turn. The phase begins without conflicting vehicular movements; conflicting movements begin after several seconds and continue through the remainder of the bike signal phase. Turning motor vehicle speeds are managed through geometric design.
Similar to a Leading Pedestrian Interval (LPI), this combination serves people of all ages and abilities at a high degree of comfort and service. LPIs reduce serious crashes and injuries for people walking by 10-30%.2
LBIs are recommended as a widespread treatment for signalized intersections without dedicated turn lanes that meet the contextual thresholds for permissive or partially protected bike phases.
LBIs and LPIs typically last the same duration when implemented together. LBI duration should be based on the width of the street being crossed as measured from the bike stop line. An LBI is typically at least six seconds. At shorter crossings and in low-speed conditions, an LBI may be as few as three seconds. Apply engineering judgment based on actual conditions at the intersection, including vehicular turn volumes, visibility, grade, crash history, current and expected bike and pedestrian volumes, and the percentage of heavy vehicles moving through the intersection.
Use bike signals to indicate the LBI. Maintain the green bike signal phase during concurrent vehicle turn movements. Using a bike signal with this configuration is experimental in the U.S., but has shown no trend of safety concerns across applications in the U.S. and in Canada.
TURNING VEHICLES YIELD TO PEDESTRIANS (MUTCD R10-15) signs may be used or modified to include bikes.
Variation: Allow bikeway users to proceed on an LPI
Add a BICYCLES USE PEDESTRIAN SIGNAL (MUTCD R9-5) sign to an LPI to create the same operational conditions as an LBI. This option does not require the use of bike signals or require experimentation in the U.S. Allowing bikeway users to proceed with LPI phases is a low-cost way to improve safety at intersections along a bikeway.
Some jurisdictions, including the State of California, New York City, the District of Columbia, and the Province of Quebec, allow bike traffic to proceed on a pedestrian signal by default. LBIs created with bike signals are preferable to this condition, as they improve legibility across various contexts and allow for accurate bike clearance times. Only consider this option if the pedestrian signal is easily visible to people using the bikeway.
Consider modifying the BICYCLES USE PEDESTRIAN SIGNAL (MUTCD R9-5) sign to say MAY USE, which more explicitly allows people in the bikeway to enter the intersection while the pedestrian signal is in Flashing Don’t Walk or Don’t Walk but the parallel vehicle traffic still faces a green signal.
Variation: “No Turns” blank-out sign
Use a green signal for both the bike and vehicle movement with a blank-out “no right turn,” “no left turn,” or “no turns” sign to create operational conditions similar to an LBI without installing bike signals. During the first part of the green phase, illuminate the blank-out sign to prohibit turns, allowing people on bikes a head start.
This phasing strategy can be used with or without dedicated turn lanes. If installed without dedicated turn lanes to store turning motor vehicles, through-moving drivers wait behind any turning vehicles but can proceed if the lead motor vehicle is not turning. This configuration does not require experimentation in the U.S.
Split LBI
Split LBIs allow vehicle through movements to start at the same time as the parallel bikeway. Bikeway users and drivers heading through the intersection are served a green bike and green signal, respectively. Pedestrians receive a Walk. Turning drivers face a red arrow signal. During the next phase, the bike green, Walk, and through vehicle movements all continue. Turning motor vehicles receive an FYA turn phase.
This phasing strategy is applicable on streets with and without transit lanes, with both unidirectional and bidirectional bikeways, and on streets that provide one-way or two-way vehicular travel.
Bike signals are required. This configuration is experimental in the U.S.
Lagging Lefts
On two-way streets with signalized left turn lanes, hold the left turn while through vehicle, bike, and parallel pedestrian traffic moves through the intersection. The left turns can proceed in a protected phase.
Lagging left turns are useful in many intersections and are particularly effective in reducing crash rates where the left turn crosses multiple travel lanes and a bikeway. Lagging left turns can be applied on one-way streets with left-aligned bikeways to give people biking and walking the opportunity to cross without conflicts and with minimal delay. In this context, confirm that the signal coordination does not result in bikeway users arriving at the intersection after the lefts have begun.
Bike signals are not required.
Overlap Turns
In very busy intersections, overlap phases can efficiently process vehicle traffic separately from bike traffic.
Permissive Phases
Intersections without bike phases must meet contextual guidance on the number of conflicting turns over the bikeway per cycle. Ensure that the total time provided for the bikeway crossing allows people who arrive at the end of the yellow phase enough time to complete the crossing. (See Signal Phasing and Timing Strategies – Signal Operations.) If the bikeway approach is not on recall, people in the bikeway must be able to be detected reliably.
TURNING VEHICLES YIELD TO PEDESTRIANS (MUTCD R10-15) signs may be used or modified to include bikes. Consider installing blank-out signs indicating that turning vehicles must yield to bikes. These signs are activated by detecting an approaching bikeway user.
- “The high rate of minor conflicts typically occur during the turning vehicle phase when bicyclists would continue through the intersection (disregarding the red bicycle signal indication).”
New York City Department of Transportation. Cycling at a Crossroads: The Design Future of New York City Intersections. NYCDOT, 2018. https://www.nyc.gov/html/dot/downloads/pdf/cycling-at-a-crossroads-2018.pdf. ↩︎ - Results from studies in Chicago, New York and Charlotte resulted in a CMF of 0.87 or a 13% reduction in crashes.
Federal Highway Administration. Safety Evaluation of Protected Left-Turn Phasing and Leading Pedestrian Intervals on Pedestrian Safety. Publication Number FHWA-HRT-18-044. USDOT, 2018. https://www.fhwa.dot.gov/publications/research/safety/18044/index.cfm. ↩︎