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32 5 Right-Turn Phasing Mode The choice of right-turn phasing mode is often less deliberate than left-turn phasing mode. However, the appropriate right-turn treatment can help optimize right-turn delay and safety, particularly related to conflicts between right-turning vehicles and pedestrians. In addition to addressing right turns, this section of the Guide is also most appropriate for addressing left turns from a one-way street to another one-way street. 5.1 Right-Turn Phasing Modes As with left turns, right turns can operate using one of the following phasing modes: ⢠Permissive-Only, where right turns are usually served by a circular green or flashing yellow right arrow signal indication. During a permissive right-turn movement, a pedestrian phase can be served across the right-turn movementâs departing lanes. Right-turning drivers are required to yield to pedestrians in the parallel crosswalk when turning right on a permissive mode. ⢠Protected-Only, where right turns can be made on a green right arrow indication. During a protected right-turn movement, no conflicting traffic or pedestrian phases may be served, and no phases may be served that use the same departing lanes (unless sufficiently channelized). ⢠Protected-Permissive, where both modes may be used on the same approach during the same signal cycle. The right-turn mode may also change by time of day or in response to changing traffic conditions. Right turns may also be uncontrolled by a traffic signal where the right-turn movement is physically channelized away from conflicting traffic movements and has its own approach lane(s). 5.1.1 Signal Faces Right-turn movements are controlled by one of two types of signal face: ⢠Shared signal face, where the same signal face controls the right-turn movement and another movement (usually the through movement) on the same approach. ⢠Separate signal face, where a signal face controls only the right-turn movement. In most states, a steady red right-turn arrow in a separate signal face communicates to motorists that right turns on red (RTOR) are prohibited. However, a regulatory sign, such as NO TURN ON RED (R10-11) is recommended to supplement the signal display to ensure that motorists are aware of the law. If a separate right-turn signal face is used on an approach where RTOR is permissive, a steady circular red should be used.
33 Table 4 illustrates how the two types of signal displays are typically used to communicate each of the three possible right-turn phasing modes. While the displays in the table are typical, other configurations are possible. Table 4 - Right-Turn Signal Faces for Each Right-Turn Phasing Mode Right-turn phasing mode Example shared signal face Example separate signal face Where RTOR are prohibited Where RTOR are permitted Permissive-Only *Flashing *Flashing Protected-Only A shared face may only be used where the circular green and green right arrow always start and end together. Protected-Permissive *Flashing *Flashing 5.2 Right-Turn Phasing Considerations The following roadway and traffic features influence the selection of a right-turn phasing mode.
34 Visibility Vi sib ili ty To allow permissive right turns, right-turning drivers must have a clear view of the adjacent parallel crosswalk and the pedestrian waiting areas on the near and far sides of the street. Blocked line of sight between drivers and pedestrians Protected-Only recommended Lane Configuration La ne C on fig ur at io n On an approach without an exclusive right-turn lane, permissive-only phasing mode is almost always used. The MUTCD allows protected-only phasing in this case, but only where the right-turn movement starts and ends at the same time as the adjacent through movement (FHWA 2009b). Permissive-Only required unless Split Phasing is used On an approach with only one exclusive right-turn lane, permissive- only phasing mode is normally appropriate, except in cases such as the following, where protected-only phasing mode should be considered: ⢠Where right turns conflict with a high volume of pedestrians or bicycles ⢠Where right-turning vehicles encounter an at-grade railroad crossing just beyond the turn ⢠Where right-turning vehicles encounter other driveways or intersections just beyond the turn that introduce unexpected conflicts Permissive-Only recommended, except as stated in the text On an approach with more than one exclusive right-turn lane and a parallel pedestrian phase, some agencies avoid permissive-only right- turn phasing mode because drivers in the outside right-turn lane may not have a clear view of conflicting pedestrians. However, permissive- only right-turn phasing mode is not prohibited by the MUTCD. with conflicting pedestrian phase Protected-Only recommended
35 La ne C on fig ur at io n On an approach with an exclusive right-turn lane and an adjacent shared through-right lane, the MUTCD does not limit right-turn phasing mode options. A protected right-turn phase that starts or ends at a different time than the through movement is not ideal, because drivers in the shared lane will have different green times based on their intended movement, potentially contributing to uncertainty that could lead to rear-end crashes. However, if the approach has a conflicting pedestrian phase, permissive-only phasing is not ideal because right-turning drivers in the shared lane may not have a clear view of conflicting pedestrians. The ideal phasing mode for this approach is a protected-only right turn that starts and ends at the same time as the through movement but is served at a different time of the signal cycle than the parallel pedestrian phase. It may be more operationally efficient and may offer safety benefits to consider a lane configuration that avoids the shared lane. without conflicting pedestrian phase Permissive- Only recommended with conflicting pedestrian phase Protected-Only that starts and ends at the same time as the through movement recommended Right-Turn Overlap Ri gh t-T ur n Ov er la p A right-turn overlap provides a protected right-turn phase when the cross-street left-turn is served and usually also allows permissive right turns on a circular green indication. A right-turn overlap can increase turning speed when compared with RTOR and improve traffic operations during a portion of the cycle when pedestrians are already prohibited from crossing. When any lane is shared by right- turning traffic and another movement, a right-turn overlap should not be used. Right-turn overlaps are more operationally beneficial with higher right-turn volume. Some agencies have established thresholds to help determine when to consider right-turn overlaps. For example, Virginia considers a right-turn overlap if right-turn volume exceeds 200 vehicles per hour (FHWA 2009b; Virginia Department of Transportation 2011). without significant cross-street U-turn conflict Protected- Permissive optional
36 Ri gh t-T ur n Ov er la p (C on tin ue d) A right-turn overlap can cause a conflict between right-turning vehicles and cross-street traffic making a U-turn. Laws in some states require U-turning drivers to yield to right-turning vehicles when both have a green arrow, but the yielding operation introduces friction between the vehicles no matter which movement yields. Some agencies, such as those in California, do not permit this conflict to exist regardless of traffic volume (California Department of Transportation, 2014). One of the following strategies should be considered to mitigate the conflict: ⢠Eliminate the right-turn overlap and use permissive-only phasing. RTOR could still be permitted. Alternatively, right turns could be permitted on a flashing yellow arrow instead of a green arrow when the cross-street left- turn is served, indicating that right-turning drivers must yield but a stop is not required. ⢠Protected-permissive right-turn phasing mode could still be used, but this would require the protected right-turn movement to be served at a different time of the cycle than the complementary left turn. The protected right turn also could not operate at the same time as the parallel pedestrian movement. Because of these inefficiencies, protected-permissive right-turn phasing mode is not often used without a right-turn overlap. ⢠Prohibit U-turns from the cross-street. ⢠Less desirably, post a sign such as U-TURN YIELD TO RIGHT TURN (R10-16) to indicate the desired yielding behavior. However, some motorists may not understand the message intended by signs such as this. with significant cross- street U-turn conflict Permissive-Only recommended
37 Consideration for Pedestrian Movements Ri gh t-T ur n Co nf lic ts w ith P ed es tr ia n M ov em en ts On an approach with a parallel pedestrian phase,1 the MUTCD prohibits a right-turn green arrow when it conflicts with symbolic or text WALK or flashing DONT WALK indications (FHWA 2009b). with conflicting pedestrian phase Right-turn green arrow and pedestrian phase shall not occur simultaneously On an approach without a parallel pedestrian phase,1 laws in most states allow pedestrians to cross on the circular green indication. The MUTCD does not expressly prohibit a green arrow during this âstatutoryâ pedestrian phase, but serving an arrow remains a potential conflict. Some agencies use complex signal programming to prevent the display of the right-turn green arrow if a pedestrian pushbutton has been actuated but enable the arrow at other times. While this programming complies with the MUTCD, it does not appear to offer any operational benefits over permissive right turns during the circular green indication. without conflicting pedestrian phase but where pedestrians are permitted Right-turn green arrow and circular green should not occur simultaneously On approaches where pedestrians are prohibited from crossing the right-turn movementâs departing lanes, a right-turn green arrow may be used. with no conflicting pedestrian phase and no legal conflicting pedestrian crossing Right-turn green arrow and circular green may occur simultaneously On approaches with an exclusive right-turn lane, a high right-turn volume, and a high parallel pedestrian crossing volume, agencies may consider using protected-only right-turn phasing mode. This allows right turns and pedestrians to be served at different times in the signal cycle, avoiding the conflict. with high-volume conflicting parallel pedestrian crossing Protected-Only recommended
38 Considerations for Bicyclists Bi cy cli st s On an approach with an exclusive right-turn lane and a separated bike lane where through bicyclists (in either or both directions) are directed to ride to the right of a right-turn lane, a conflict is created between through bicyclists and right-turning vehicles. The conflict can be avoided using protected-only right-turn phasing mode, serving bicycles during a different portion of the signal cycle than right turns. In this case, bicyclists can usually be served at the same time as pedestrians and through traffic. with conventional signal indications Protected-Only recommended (FHWA 2015) Bicycle signal indications are not included in the 2009 MUTCD but are available to practitioners as part of an FHWA Interim Approval (IA) (FHWA 2013a). On approaches with an exclusive right-turn lane where bicycle signal indications are used, the IA requires all conflicting vehicular movements to be prohibited during display of the green bicycle signal, including RTOR and permissive right turns. with bicycle signal indications Right-turn green arrow and green bicycle signal shall not (FHWA 2013a) be displayed simultaneously When protected-only right turns are needed because of a temporary condition, such as the presence of high volume of conflicting pedestrians, it may be desirable to consider using a variable right-turn phasing mode. A variable mode can change by time of day, week, or year, such as to account for times when pedestrian volumes are known to be high. A variable mode can also change dynamically in response to intersection conditions, such as using protected-only right-turn phasing mode only when a parallel pedestrian crossing has been actuated. An alternate strategy is to prohibit RTOR at times when certain conditions are prevalent. 5.3 Other Considerations A LPI may help reduce conflicts between pedestrians and right-turning vehicles. LPIs are discussed in more detail in section 7.1.2. A right-turn overlap may complicate street crossings for pedestrians with visual impairments. A continuous flow of right-turning vehicles, first protected and then permissive, may make it difficult to detect the sound of through traffic, which is used to determine when to start crossing (FHWA 2013b). Accessible Pedestrian Signals (APS) help overcome this difficulty. 1 A pedestrian phase means the movement is controlled with pedestrian signal heads that display symbolic or text WALK and DONT WALK indications.
