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Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges (2021)

Chapter: Chapter 7 - Restricted Crossing U-Turn (RCUT) Intersections

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Suggested Citation:"Chapter 7 - Restricted Crossing U-Turn (RCUT) Intersections." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 7 - Restricted Crossing U-Turn (RCUT) Intersections." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 7 - Restricted Crossing U-Turn (RCUT) Intersections." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 7 - Restricted Crossing U-Turn (RCUT) Intersections." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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Suggested Citation:"Chapter 7 - Restricted Crossing U-Turn (RCUT) Intersections." National Academies of Sciences, Engineering, and Medicine. 2021. Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges. Washington, DC: The National Academies Press. doi: 10.17226/26072.
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7-1 7.1 Introduction The Restricted Crossing U-Turn (RCUT) intersection, also called a reduced conflict inter- section (RCI), a superstreet intersection, a J-turn intersection, or a synchronized street inter- section, differs from a conventional intersection by eliminating the left-turn and through movements from cross street approaches. To accommodate these movements, the RCUT inter- section requires minor street drivers to turn right onto the major street and then make a U-turn maneuver at a one-way median opening downstream of the main intersection. At the major street approaches, the left-turn movements are typically accommodated similarly to left-turn movements at conventional intersections. Sometimes, left-turn movements from the major street can be removed and redirected to the downstream U-turn crossover. The RCUT intersection is similar to the MUT intersection. However, these alternative inter- section types each have unique design features and are implemented at different locations with unique characteristics: • Both intersections reroute minor street left-turn movements. However, the RCUT inter- section also reroutes minor-street through movements; the MUT does not. The MUT typically reroutes major street left-turn movements; the RCUT typically does not. • The RCUT intersection typically has better signal progression than the MUT intersection but does not serve minor street approaches with high through demand as well as the MUT intersection. • The RCUT intersection may complement a corridor with MUT intersections by serving intersections that are mostly turning movements to and from the minor street, with the MUT intersections serving those intersections that also have significant through movements on the minor street. RCUT intersections can have either three or four legs. With a four-legged RCUT intersection, there are two U-turn crossovers, and minor street left-turn and through movements are not allowed to be made directly at the intersection. There are three main types of RCUT intersections: • Signalized. A signalized RCUT intersection can provide favorable progression along an urban or suburban corridor. RCUT intersection signals typically require only two phases, which can minimize the lost time at the intersection. Because each direction of the major street is controlled by a two-phase signal that can be operated independently of the other direction, efficient progression can be provided in both directions with any speed or signal spacing. • Stop-controlled. A stop-controlled RCUT intersection is sometimes used as a safety treat- ment at an isolated intersection on a four-lane divided arterial in a rural area. There are known C H A P T E R 7 Restricted Crossing U-Turn (RCUT) Intersections

7-2 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges vehicular safety benefits with this RCUT intersection. Sometimes, a stop-controlled RCUT intersection is later converted to a signalized RCUT intersection if traffic volumes increase. • Merge- or yield-controlled. Where funding for interchanges and overpasses may not be readily available, a merge-controlled RCUT intersection can allow a rural high-speed divided four-lane corridor to function similarly to a freeway corridor. This RCUT intersection relies on long distances to U-turn crossovers to enable motorists to make the movement. Hybrids of the three main types of RCUT intersections are possible, and the RCUT inter- section is sometimes converted from one type to another. Exhibit 7-1 presents vehicular move- ments at an RCUT, overlaid on pedestrian and bicycle routes. Much of the material in this chapter is derived from earlier work for FHWA (1) and has been updated to reflect the knowledge gained in this research. 7.2 Multimodal Operations This section presents the multimodal operational characteristics of an RCUT intersection, starting with motorized vehicles and then explaining how pedestrians and bicyclists are served. 7.2.1 Motorized Vehicles Exhibit 7-2 shows the concurrent eastbound movements and concurrent westbound move- ments at a typical signalized RCUT intersection. Mainstreet through movements at an RCUT intersection can operate independently of each other, allowing for unique cycle lengths and offsets in each direction. Exhibit 7-3 shows the typical signal locations for this configuration. Signals at the RCUT main intersections (Signals 1 and 4 in the exhibit) traditionally operate with two phases: one for the major street through movement and one for the major street left-turn movement and minor street movements. As will be seen later, an additional phase is sometimes added to facilitate minor street pedestrian and bicycle crossing movements at the main inter- section. Similarly, the signals at the RCUT crossover intersections (Signals 2 and 3 in the exhibit) traditionally operate in two phases. A phase is sometimes added at the crossover signals to serve traffic turning right from a driveway or side street. Signal timing at an RCUT intersection or corridor is fundamentally different from that of any other intersection or corridor, due to the ability to have different cycle lengths in each direc- tion of the major street. Signal timing at an RCUT intersection or corridor can use a common Exhibit 7-1. Example of an RCUT intersection with signals.

Restricted Crossing U-Turn (RCUT) Intersections 7-3 cycle length in both directions of the major street or a different cycle length for each direction of the major street. If a common cycle length in both directions is used, there is an opportunity to provide for some progression for the movements using the crossovers. This can also facilitate design configurations (see Section 7.4) that facilitate one-stage crossings for pedestrians and bicyclists. With different cycle lengths in each direction, most pedestrians and bicyclists will likely cross the major street in two stages (with a delay in the median), and minor street motorist movements will likely not be progressed. These challenges can be mitigated by using cycle lengths with a common denominator and prioritizing bicycle and pedestrian progression. 7.2.2 Pedestrians Depending on their configuration, RCUT intersections may require pedestrian crossings that differ substantially from those at conventional intersections. The RCUT intersection’s wide geometric footprint can make it challenging to accommodate pedestrians, but the short cycle lengths associated with RCUT intersection operations can help make the crossing times of pedestrian movements more comparable to those at conventional intersections. Pedestrian crossings at RCUT intersections must be accessible for all users, including those with visual impairments. Therefore, the provisions for pedestrians must consider the need to Exhibit 7-2. Concurrent eastbound movements and concurrent westbound movements at signalized RCUT intersection. Exhibit 7-3. Signal placement at signalized RCUT intersection.

7-4 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges communicate crossing patterns in nonvisual ways, using wayfinding techniques discussed in the PROWAG (2). This may include audible devices, channelization, and separation and detectable delineation of the pedestrian route and crossing. These concepts are discussed in more detail in Chapter 2. 7.2.2.1 Main Intersection One of the common means of serving pedestrians at an RCUT intersection is a “Z” crossing treatment, shown in Exhibit 7-4. A “Z” crossing allows all six desired pedestrian movements at an intersection. The two minor street crossings (A to B, C to D) are made similarly to those at a conventional intersection. Three of the movements (A to C, B to D, and A to D) require pedestrians to take a longer route via the “Z” crossing. The sixth movement (B to C) allows pedestrians to make a more direct diagonal movement across the intersection. Exhibit 7-5 shows a “Z” crossing at a signalized RCUT intersection near San Antonio, TX. The major road crossing distance could be shortened by adding a raised barrier or channel- ization between major street through lanes and major street right-turn lanes. Exhibit 7-4. Pedestrian movements in an RCUT intersection. Exhibit 7-5. Signalized RCUT with “Z” crossing near San Antonio, TX (2).

Restricted Crossing U-Turn (RCUT) Intersections 7-5 Despite the common application of the “Z” crossing, RCUT intersections can be served with pedestrian crossings that are more direct and reduce both geometric and operational pedestrian delay. In Section 7.4, pedestrian crossing options that differ from the common “Z” crossing are shown. 7.2.2.2 U-turn Crossover U-turn crossover intersections create additional opportunities for midblock pedestrian cross- ings. The details and options for the U-turn crossover are the same for RCUT intersections as for MUT intersections. Detail on U-turn crossovers is in Chapter 6. 7.2.3 Bicyclists The three primary ways to serve minor street through and left-turn bicyclists in an RCUT intersection are by using the following: • A “Z” crossing with pedestrians (if one is provided); • A more direct route (if provided); and • A route similar to motor vehicle traffic using the U-turn crossover. These options are illustrated in Exhibit 7-6. Designs can vary substantially, depending on the context and travel patterns for each mode being served. Although the “Z” crossing may be suitable if the pathway through the intersection is designed for shared use and is wide enough to be comfortable for bicyclists, it introduces substantial out- of-direction travel for bicyclists. The second option, the direct bicycle crossing, features some alternatives introduced in Section 6.4. These allow separated bicycle facilities and the protected intersection concept (see Section 5.2.6) to be applied to the main RCUT intersection. An unsignalized version may also be used in some contexts, such as in Exhibit 7-7, which shows a treatment used in North Carolina to aid minor street left-turning and through bicyclists in negotiating a rural RCUT intersection with stop-control and no pedestrian facilities due to the lack of nearby pedestrian- generating land uses. The treatment consists of curb cuts and narrow paths through the median. Signs should direct bicyclists to the crossing, because it otherwise may not be apparent that it is intended for them. Exhibit 7-6. Minor street through options for bicycles.

7-6 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges The third option, using the U-turn crossover, introduces a substantial safety challenge for bicyclists, because the path to the U-turn crosses that of through motorists. The U-turn itself may be difficult for bicyclists, because motorists making U-turns may have difficulty staying in lanes, and large vehicles may produce greater off-tracking into lanes occupied by bicyclists. 7.3 Safety and Comfort This section discusses safety and comfort principles for pedestrians and bicyclists at RCUT intersections. For motor vehicles, RCUT intersections have been shown to result in significant safety benefits compared to standard four-legged intersections. The safety benefits for vehicles are attributable to eliminating left-turns at the main intersection and simplifying driver decision- making (that is, by generally dealing with one direction of travel at a time). The RCUT offers potential safety benefits for pedestrians through reduced conflict points, but no safety data have shown quantitative safety benefits for pedestrians or bicyclists. The biggest safety risk for pedes- trians and bicyclists is for those users who, due to excessive delay or indirect paths, try to find paths that differ from the intended design. Desired pedestrian and bicycle operations need to be developed at the beginning of Stage 2 of the ICE Process to develop geometric elements. Once geometric elements are developed, the focus can shift to the specific safety elements within the geometry, as described below. 7.3.1 Conflict Points The conflict points for pedestrians at an RCUT can vary depending on the geometric configu- ration. At an RCUT intersection, left-turns are removed from the minor street and occur away from the intersection, thus removing potential pedestrian exposure to left-turning vehicles. However, the volume of vehicles turning right to the minor street is higher than at a conven- tional intersection. Exhibit 7-8 shows the pedestrian conflict points with an RCUT intersection design using a “Z” crossing. An RCUT intersection reduces the number of vehicle-pedestrian conflict points relative to conventional intersections by using a “Z” crossing. However, movements requir- ing a longer unconventional route (against the “Z”) or having more conflict points may tempt Exhibit 7-7. Curb cut design used in North Carolina to assist bicyclists crossing at a rural RCUT with a stop sign.

Restricted Crossing U-Turn (RCUT) Intersections 7-7 pedestrians to cross the major street directly or to cross from the center diagonal island to one of the alternate quadrants. Bicyclists on the major street travel though an RCUT intersection the same way they travel through a conventional intersection. Minor street left-turning or through bicyclists do not have a direct route at a typical RCUT intersection unless such facilities are provided, as dis- cussed in Section 7.4. RCUT intersections can reduce or eliminate out-of-direction travel by bicyclists. Both the challenges and benefits that RCUT intersections offer bicyclists must be evaluated carefully to guide project planning and design decisions. 7.3.2 Pedestrians–Key Safety Challenges Similarly to the MUT intersection, the RCUT intersection can enhance pedestrian safety by simplifying vehicular movements and eliminating left-turns. The remaining pedestrian safety concerns specific to the RCUT intersection are as follows: • Compared to a conventional intersection, the RCUT intersection is likely to result in an increased vehicular right-turning volume, because left-turns have to make a right-turn to get to the U-turn crossover (minor street left-turn and through movements) and make a right- turn after the U-turn maneuver (minor street through movements). These right-turns may be controlled to ensure safe pedestrian crossings, and the high volume of right-turns could exacerbate the Motor Vehicle Right-Turns design flag (Section 4.4.1). However, RCUTs inher- ently avoid the Motor Vehicle Left-Turns design flag (Section 4.4.10) for the minor street. • The Z-crossing configuration at some RCUT intersections results in some out-of-direction travel for pedestrians crossing “against the Z.” For these movements, additional exposure and delay are introduced for the additional crossing points. The additional length should be evaluated using the Indirect Paths design flag (Section 4.4.5). • Depending on the signal timing, pedestrian delay for a full crossing can be high, because the middle segment of the Z-crossing usually requires a two-stage crossing with multiple delay points. This condition triggers the Long Red Times design flag (Section 4.4.8). • A supplemental pedestrian crossing can be provided at each U-turn location, given it is a signal-control location for the U-turns. The outbound vehicular travel lanes rarely are signalized but would necessitate a control device or treatment if a crossing is provided so as to avoid forcing pedestrians to cross multiple uncontrolled high-speed vehicular travel lanes. If no signal was provided for the outbound vehicular movement, the Crossing Yield- controlled or Uncontrolled Vehicle Paths flag (Section 4.4.4) would be triggered. Exhibit 7-8. Pedestrian-vehicle conflict points at an RCUT intersection.

7-8 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges In consideration of these challenges and pedestrian conflict points, Exhibit 7-9 presents the design flags applicable to pedestrians, along with the location of their discussion and applicable treatments (design flags and treatments whose discussion applies across alternative intersection types are in Chapter 5). Some design flags unlikely to be present at an RCUT intersection include the following: • Nonintuitive motor vehicle movements (Section 4.4.3): No motor vehicle movements are crossed over or otherwise approaching from an unintuitive direction for people crossing at an RCUT. • Executing unusual movements (Section 4.4.6): The wayfinding, traversing, and crossing at RCUTs are relatively straightforward, without unexpected directionality or unintuitive turns. Flag Description Mode/Travel Path Motor Vehicle Right-Turns (Section 4.4.1) This flag would carry forward to the final design stage, based on right-turns. Because RCUTs have relatively high volumes of right- turns, the geometry of the turning movement will be a critical factor in controlling speeds. Pedestrian, all crossings Crossing Yield- or Uncontrolled Vehicle Paths (Section 4.4.4) With the right-turns identified in the design flag above, pedestrians at the main intersection crossings would cross a high volume of right-turning vehicles with a green signal indication. Pedestrian, all main intersection crossings Indirect Paths (Section 4.4.5) Major street crossings that conflict with high-volume minor street right-turns are sometimes closed at an RCUT. In such cases, pedestrians are rerouted via a Z- crossing or similar arrangement. Multilane Crossings (Section 4.4.7) The major street crossings at an RCUT may be relatively long. A median refuge is common, but the single-direction travel lane configuration may remain a long crossing. Pedestrians, all crossings Undefined Crossing at Intersections (Section 4.4.9) This flag is not unique to RCUTs, but given the relatively high volume of right-turning vehicles conflicting with the pedestrian crossing, lack of clearly defined user space would be stressful for pedestrians. Pedestrians, all crossings Long Red Times (Section 4.4.8) If trying to cross “against the Z,” pedestrians or bicyclists may have a high amount of travel time delay that would incentivize risk- taking behavior. Pedestrians with an origin-destination pattern contrary to the walking path conveyed by the intersection in a Z-crossing Pedestrians with an origin-destination pattern contrary to the walking path conveyed by the intersection in a Z-crossing Exhibit 7-9. Design flags applicable to pedestrians at RCUTs.

Restricted Crossing U-Turn (RCUT) Intersections 7-9 7.3.3 Bicycles–Key Safety Challenges At RCUTs, bicycles may travel on shared-use path systems along with pedestrians, travel on a dedicated separated bicycle facility, or operate in a shared environment with vehicles. For bicycles traveling in on-street facilities, these additional safety challenges apply: • Bicycle left-turn and through movements from the minor approach face significant out- of-direction travel (to and from the U-turn), as well as safety risks in needing to perform a crossover maneuver across potentially busy and fast-moving vehicular travel lanes. This is described by the Lane Change Across Motor Vehicle Travel Lanes design flag (Section 4.4.16). • No clear direct path option exists for bicycle left-turns and minor street through movement without modifying the design (see Section 7.3). This triggers the Indirect Paths design flag (Section 4.4.5). • Bicycle right-turns may conflict with pedestrian crossings and potentially high right-turning vehicle volumes. • If channelized lanes are provided on any approach, the design issues in Channelized Lanes (Section 4.4.17) apply. Safety concerns related to the design of the channelized lanes are discussed further in Chapter 5. Exhibit 7-10 presents the design flags applicable to bicycles at RCUTs. Design flags and treat- ments whose discussion applies across alternative intersection types are provided in Chapter 5. 7.3.4 Other Safety Concerns In addition to the preceding discussion of key pedestrian and bicycle safety concerns, RCUT intersections present other general benefits and concerns. Design flags that are more universal and not unique to RCUTs include the following: • Intersection Driveways and Side Streets (Section 4.4.11); • Sight Distance for Gap Acceptance Movements (Section 4.4.12); • Grade Change (Section 4.4.13); and • Off-tracking Trucks in Multilane Curves (4.4.20). Some design flags typically eliminated by the RCUT design include nonintuitive motor vehicle movements (Section 4.4.4). The RCUT introduces no crossover movements or atypical travel directions that would be unintuitive to a road user. Sometimes, these design flags may need to be resolved in subsequent stages of design. 7.4 RCUT Intersection-Level Concepts Four design concepts have been developed to present options for improving pedestrian and bicycle safety and operational performance at RCUT intersections. These concepts are not suggested as designs to be replicated as is; rather, they illustrate the RCUT options possible in various contexts. These concepts mix design approaches. The designer must consider traffic volume and speed when matching designs and treatments to the appropriate context. Following each concept is a discussion of the flags remaining with the design—the flags not obviated by the design that would still need to be addressed. The designs include the following: • RCUT Bike Lane and Path Concept • RCUT Shared-Use Path Concept • RCUT Separated Bike Lane Concept • Rural RCUT Shoulder Concept

7-10 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 7.4.1 RCUT Bike Lane and Path Concept This RCUT concept (shown in Exhibit 7-11) is distinguished by its provision of on-street bike lanes along with a shared-use path. The concept would be appropriate for a low-speed and/or low-volume context and provides an example for carrying existing bike lanes through an RCUT; consult Sections 3.1 and 3.3 to consider intended bicycle design users and guidance for matching a bicycle facility to speed and volume conditions. 7.4.1.1 Benefits The RCUT concept is shown in Exhibit 7-11 and includes the following key elements: • Motor Vehicle Right-Turns design flag: Where pedestrian crossings exist, corner refuge islands tighten right-turn radii and extend physical protection for crossing pedestrians. Though this turn radius may need to be modified based on the intended design vehicle path, the design would control speeds of right-turning vehicles. Additionally, although the removal of a crossing triggers other flags, this removal eliminates pedestrian conflicts with the antici- pated high volume of vehicle right-turns. Design Flag Description Mode/Travel Path Indirect Paths (Section 4.4.5) For bicyclists seeking to make a left- turn at the intersection or a through movement along side streets, the U- turn as designed represents considerable out-of-direction travel (several hundred feet), which may exceed thresholds for yellow or red flags (see Section 4.4.6). Bicyclists making left- turns via U-turn maneuver at RCUTs Multilane Crossings (Section 4.4.7) For bicyclists crossing with pedestrians or using a path, the major street crossings at an RCUT may be relatively long. A median refuge is common, but the single- direction travel lane configuration may remain a long crossing. Bicyclists, all path crossings Undefined Crossing at Intersections (Section 4.4.9) The movements are not clearly demarcated for the common expectation for left-turning bicyclists to proceed straight through the signal and cross over traffic to make a U-turn. Bicyclists making left- turns via U-turn maneuver at RCUTs Lane Change Across Motor Vehicle Travel Lane(s) (Section 4.4.16) Bicyclists making the U-turn maneuver must cross over one or several lanes of motor vehicle traffic on a tangent roadway section to position for the U-turn. Bicyclists making left- turns via U-turn maneuver at RCUTs Turning Motorists Crossing Bicycle Path (Section 4.4.18) The expected relative high right- turn volumes at an RCUT exacerbate potential conflicts between right- turning vehicles and through bicyclists. Through bicyclists (particularly on the major street) Exhibit 7-10. Design flags applicable to bicyclists at RCUTs.

Restricted Crossing U-Turn (RCUT) Intersections 7-11 • Indirect Paths design flag: For bicyclists, the design includes on-street bike lanes with ramps to shared-use paths. This feature has the benefit of providing an off-street left-turn or minor street through movement for all bicyclists (through the “Z”) and mitigates the Indirect Paths design flag. For pedestrians, the ability to cross all four legs of the intersection (as well as the supplemental crossings at the U-turn) promotes accessibility and eliminates circuitous paths. • Crossing Yield-Controlled or Uncontrolled Vehicle Paths design flag: All pedestrian cross- ings would be signal-controlled, providing safe crossing opportunities and eliminating the possible associated design flag. • Physical Separation for Bicyclists: For bicyclists who use the available ramps, this concept moves their riding away from mixed traffic with physical separation. Bicyclists would cross motor vehicle paths using marked crossings; consult Chapter 5 for guidance on these cross- ings. This design eliminates the following design flags: – Riding in Mixed Traffic; – Bicyclist Crossing Motor Vehicle Travel Lane(s); – Turning Motorists Crossing Bicycle Path; and – Riding between Travel Lanes, Lane Additions, or Lane Merges. Where right-turning vehicles would cross the through bike movements, the crossings are recessed to promote bicyclist visibility. • Shared-use path system in the Z-crossing configuration for pedestrians and bicyclists with all signalized crossings; • Two-stage pedestrian crossings across the major roadway with wide median refuge. 7.4.1.2 Challenges The bike lane and path concept leaves some design flags remaining (see Exhibit 7-12). As two paths for the bicyclists are provided, this analysis will be conducted assuming the bicyclist uses the shared-use path. If the on-street bicycle lanes were considered for analysis, different flags would apply. 7.4.2 RCUT Shared-Use Path Concept This RCUT shared-use path concept (shown in Exhibit 7-13) is distinguished by its imple- mentation of a shared-use path through the intersection. The design concept also features crossings on all four intersection approach legs. The concept is intended to be implemented in Exhibit 7-11. RCUT bike lane and path concept.

7-12 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges Exhibit 7-13. RCUT shared-use path concept. Flag Remaining Description Mode/Travel Path Motor Vehicle Right- Turns (Section 4.4.1) The right-turn volume will likely be relatively high for most approaches because it is a consolidation of multiple movements. However, if the curb radii can be designed to keep speeds from exceeding 25 mph, the flag may be mitigated. Pedestrians and Bicyclists, all crossings at the main intersection Uncomfortable/Tight Walking Environment (Section 4.4.2) The careful design of the median walkway is necessary as the design progresses to ensure the walkway provides adequate space for all users. Pedestrians and Bicyclists, center median crossing Indirect Path (Section 4.4.5) The Z-crossing design requires users wanting to cross directly across the major street or from the southeast to northwest quadrants to experience out-of-direction travel. The midblock crossing may mitigate this flag for some users depending on the location of volume generators. Pedestrian and Bicyclist, direct major street crossing Multilane Crossings (Section 4.4.7) Although median refuges are included for crossing the major street, a crossing pedestrian would still cross three concurrent same- direction travel lanes crossing all streets, meriting a yellow flag. Pedestrians, all main intersection crossings Long Red Times (Section 4.4.8) RCUTs allow for independent signal timing for each major street direction of travel. If the signals are not coordinated, users crossing the major street would likely need to cross in two phases, likely resulting in a flag. Pedestrians and Bicyclists, major street crossings Exhibit 7-12. Summary of design flags remaining with RCUT Bike lane and path concept.

Restricted Crossing U-Turn (RCUT) Intersections 7-13 locations with either relatively high motor vehicle volumes or high speeds. The separated path provides a low-stress riding environment for people biking, including less confident bicyclists. The path would be appropriate for a relatively low combined expected volume of bicyclists and pedestrians. With higher volumes of both, separate facilities for each mode would be appropriate. See Sections 3.1 and 3.3 to consider intended bicycle design users and guidance for matching a bicycle facility to speed and volume conditions. 7.4.2.1 Benefits The RCUT shared-use path concept, shown in Exhibit 7-13, features the following design elements: • Motor Vehicle Right-Turns design flag: The design includes corner refuge islands that tighten turn radii and extend physical protection for crossing pedestrians. The turn radius would need to be refined based on the intended design vehicle path but would control right- turning vehicle speeds. Crossing pedestrians are pulled back to enhance their visibility. • Indirect Paths design flag: For bicyclists, the design includes separated paths that enable riders to complete left-turns in two stages and to complete a minor street through movement without a U-turn. This provides more intuitive movements for all bicyclists and mitigates the Indirect Paths design flag. For pedestrians, the midblock (at the U-turn) crossings and the four approach legs being striped provide more potential for route directness by allowing pedestrians to cross in some locations. • Crossing Yield-Controlled or Uncontrolled Vehicle Paths design flag: All pedestrian cross- ings would be signal-controlled, providing safe crossing opportunities and eliminating the possible associated design flag. • Undefined Crossing at Intersections design flag: Crossings for pedestrians and bicyclists are defined with this design; particularly for bicyclists, the path gives positive guidance and wayfinding benefits throughout the intersection. • Physical Separation for Bicyclists: This concept moves all riding through the intersection away from mixed traffic with physical (horizontal and vertical) separation and ramps to and from the shared-use paths. Bicyclists would cross motor vehicle paths using marked cross- ings; consult Chapter 5 for guidance on these crossings. This design eliminates the following design flags: – Riding in Mixed Traffic; – Lane Change Across Motor Vehicle Travel Lane(s); – Turning Motorists Crossing Bicycle Path; and – Riding between Travel Lanes, Lane Additions, or Lane Merges. Where right-turning vehicles would cross the through bike movements, the crossings are recessed to promote bicyclist visibility. • An exclusive pedestrian phase would allow the possibility of a complete pedestrian cross- ing in one stage. Additionally, the pedestrian crossings could be coordinated to minimize the delay between stages, with minimal to no disruption to vehicle signal progression. Both options would require the major street signals to be coordinated, reducing the vehicular operational benefit of the RCUT. Signal timing details would be finalized in later stages of design. Introducing a third phase at the RCUT would result in less efficient vehicle operations, compared to the standard operation with two critical phases. 7.4.2.2 Challenges The RCUT shared-use path concept leaves several design flags remaining, as presented in Exhibit 7-14.

7-14 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 7.4.3 RCUT Separated Bike Lane Concept The RCUT separated bike lane concept (shown in Exhibit 7-15) is distinguished by the sepa- rated bike lane and the removal of the major street left-turns. The design concept also features crossings on all four intersection approach legs. The concept is intended to be implemented in locations with either relatively high motor vehicle volumes or high speeds; the separated bike lane provides a low-stress riding environment for people biking and separates bicyclists from pedestrians. The removal of the major street left-turn movement would either make this Flag Remaining Description Mode/Travel Path Motor Vehicle Right- Turns (Section 4.4.1) The right-turn volume will likely be relatively high for most approaches because it is a consolidation of multiple movements. However, if the curb radii can be designed to keep speeds from exceeding 25 mph, the flag may be mitigated. Pedestrians and Bicyclists, all crossings at the main intersection Multilane Crossings (Section 4.4.7) Users crossing the major street encounter a five-lane cross section on one approach. This distance meets the flag threshold and may affect signal timing, making a complete major street crossing in one phase difficult for some pedestrians. Pedestrians and Bicyclists, major street crossing Long Red Times (Section 4.4.8) RCUTs allow for independent signal timing for each major street direction of travel. If the signals are not coordinated, users crossing the major street would likely need to cross in two phases, probably resulting in a flag. Pedestrians and Bicyclists, major street crossings Exhibit 7-14. Summary of design flags remaining with RCUT shared-use path concept. Exhibit 7-15. RCUT separated bike lane concept.

Restricted Crossing U-Turn (RCUT) Intersections 7-15 design feasible only with low volumes of left-turns or with left-turn operations as an explicit tradeoff of the design. The bike lanes would either be matched to the existing roadway or could be developed through a ramp from the approach lanes. See Sections 3.1 and 3.3 to consider intended bicycle design users and guidance for matching a bicycle facility to speed and volume conditions. 7.4.3.1 Benefits This design addresses these key elements regarding safety and comfort: • Motor Vehicle Right-Turns design flag: The design includes the protected intersection con- cept with corner refuge islands that tighten turn radii and extend physical protection for crossing pedestrians. The turn radius would need to be refined based on the intended design vehicle path but would control right-turning vehicle speeds. Crossing pedestrians are pulled back to enhance their visibility. All right-turn movement volumes are increased with this design, given the elimination of all left-turn vehicle movements. Providing an exclusive pedes- trian phase would provide time-separation of the minor street right-turns and the major street pedestrian and bicycle movement. • Indirect Paths design flag: For bicyclists, the design includes separated bike lanes enabling bicyclists to complete left-turns in two stages. This provides a more intuitive left-turn move- ment for all bicyclists and mitigates the Indirect Paths design flag. For pedestrians, the mid- block (at the U-turn) crossings provide more potential for route directness by allowing pedestrians to cross the major street upstream or downstream of the intersection. All four main intersection legs include pedestrian crossings, allowing for direct walking routes. • Motor Vehicle Left-Turns design flag: The concept eliminates all vehicle left-turns at the intersection, mitigating the associated design flag completely. This elimination of the move- ment also increases signal design flexibility, which may provide other benefits for pedestrians (although the details would be determined in a subsequent design stage). • Crossing Yield-Controlled or Uncontrolled Vehicle Paths design flag: All pedestrian cross- ings would be signal-controlled, providing safe crossing opportunities and eliminating the possible associated design flag. • Undefined Crossing at Intersections design flag: Crossings for pedestrians and bicyclists are defined with this design; particularly for bicyclists, the separated bike lane gives positive guidance and wayfinding benefits throughout the intersection. • Physical Separation for Bicyclists: This concept moves all riding away from mixed traffic with physical (horizontal and vertical) separation. Bicyclists would cross motor vehicle paths using marked crossings; consult Chapter 5 for guidance on these crossings. This design elimi- nates the following design flags: – Riding in Mixed Traffic; – Lane Change Across Vehicle Travel Lane(s); – Turning Motorists Crossing Bicycle Path; and – Riding between Travel Lanes, Lane Additions, or Lane Merges. Where right-turning vehicles would cross the through bike movements, the crossings are recessed to promote bicyclist visibility. 7.4.3.2 Challenges Operationally, if an exclusive pedestrian phase were used, this concept would remove the total independence of each major street approach from one another. The concept would not entirely remove the opportunity for two-way signal progression, but a corridor of RCUTs would need to be timed around this one to preserve the progression. The protected intersection concept leaves some design flags remaining, as presented in Exhibit 7-16.

7-16 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 7.4.4 Rural RCUT Concept with Biking on Shoulder The rural RCUT concept (shown in Exhibit 7-17) is presented with a distinctly different lane configuration and context from the other three concepts. The context for this design is along a rural corridor with a two-lane cross street. This design would be expected to be installed in a location with biking on the shoulder along the major street and limited or no existing pedestrian facilities. The concept offers a “cut-through” bike path across a single-lane U-turn and a bicycle refuge. Bicyclists on the minor street would proceed through the channelized turn lane and then Exhibit 7-16. Summary of design flags remaining with RCUT separated bike lane concept. Flag Remaining Description Mode/Travel Path Motor Vehicle Right- Turns (Section 4.4.1) The right-turn volume will likely be relatively high for most approaches because it is a consolidation of multiple movements. However, if the curb radii can be designed to keep speeds from exceeding 25 mph, the flag may be mitigated. Pedestrians, all crossings Multilane Crossings (Section 4.4.7) Although median refuges are included for crossing the major street, users would still cross four concurrent same-direction travel lanes crossing all streets, meriting a yellow flag. Pedestrians and Bicyclists, major street crossings Long Red Times (Section 4.4.8) RCUTs allow for independent signal timing for each major street direction of travel. If the signals are not coordinated, users crossing the major street would likely need to cross in two phases, likely resulting in a flag. Pedestrians and Bicyclists, major street crossings Exhibit 7-17. Rural RCUT concept with biking on shoulder example.

Restricted Crossing U-Turn (RCUT) Intersections 7-17 cross the median. Bicyclists on the major street could pull into the refuge area to cross the major street traffic at a perpendicular angle instead of crossing lanes at speed to enter the channelized left-turn lane. This concept would apply in a rural context, consistent with intended bicycle design users and guidance found in Sections 3.1 and 3.3. 7.4.4.1 Benefits This design concept addresses these key elements regarding safety and comfort: • The concept has the benefit of retaining a relatively small footprint compared to other RCUT concepts in this guide. The compact footprint would help with costs and could have residual benefits for pedestrians and bicyclists (e.g., shorter crossings and walking distances). • Indirect Paths: The concept reduces required out-of-direction travel for bicyclists at an RCUT by providing the cut-through lanes for minor street crossings. This design feature also eliminates the Lane Change Across Motor Vehicle Travel Lanes design flag; bicyclists would not need to cross over for a U-turn to make a minor street through or major street left-turn movement. • The concept retains the ability to be retrofitted to include a pedestrian Z-crossing between the major street left-turns. 7.4.4.2 Challenges The concept lacks pedestrian facilities. This approach is common in many rural areas. The lack of pedestrian facilities where people are not walking or biking perpetuates an intimidating walking environment and suppresses any latent active transportation demand. Although pedes- trian paths are not conveyed, people may need to walk through the intersection. The design flags in Exhibit 7-18 would apply for bicyclist movements. Due to the lack of pedestrian facilities, the pedestrian assessment is not completed. This design leaves flags remaining given its context and lack of pedestrian facilities. Again, the reader is cautioned that the concepts in this guide represent treatments, rather than concepts to be replicated as is. 7.5 Detailed Design Techniques The design flag procedure and corresponding flags are outlined in Chapter 4, and techniques are discussed in Chapter 5. Because many flags and techniques appear in the same fashion at many A.I.I.s, those common flags and design treatments/techniques are discussed solely in Chapter 5. Discussion in this section is limited to unique characteristics or design responses of these flags in the context of an RCUT. This includes: • Minor street turn channelization • Traffic control devices • Pedestrian crossing options • Channeling pedestrians to crossing • Crossings that conflict with minor street right-turning motorists 7.5.1 Minor Street Turn Channelization Usually, the minor street approach to an RCUT intersection will have a median dividing the two directions of travel. As with any street or channelization separating oncoming movements, medians on the minor street help drivers to avoid head-on conflicts and discourage wrong-way

7-18 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges maneuvers. Minor street medians should be at least 6 feet wide. Three options exist for channel- izing minor street traffic: • No channelizing island; • A channelizing island (or channelizing end treatment on a median) separating the right-turn lanes from the minor street lanes leaving the intersection; or • A channelizing island separating minor street right-turns that remain on the major street from minor street right-turns that make a U-turn on the major street (i.e., the redirected movements). The advantages and disadvantages of right-turn channelization on the minor street at an RCUT intersection are described in Exhibit 7-19. There are multiple ways to treat the RCUT intersection’s minor street approach, depending on the storage bay length to the U-turn crossover. One option is to align the curve leading out of the Exhibit 7-18. Rural RCUT concept with biking on shoulder. Flag Remaining Description Mode/Travel Path Crossing Yield- or Uncontrolled Vehicle Paths (Section 4.4.4) As presented, this intersection is unsignalized. Any bicyclist crossing the major street would need to find gaps in vehicular traffic. Bicyclists, major street crossings Executing Unusual Movements (Section 4.4.6) Bike refuge areas in the channelized island may not be common in the local area and bicyclists may not understand the purpose of the facility. Bicyclists, major street left-turns Undefined Crossing at Intersections (Section 4.4.9) With minimal positive guidance for bicyclists, all crossings are undefined. Bicyclists, all crossings Riding in Mixed Traffic (Section 4.4.14) Bicyclists riding through the intersection have no physical separation from motor vehicle traffic. Shoulders of appropriate width can be identified using Chapter 3 resources, but no physical separation would be provided. Bicyclists, all movements Channelized Lanes (Section 4.4.17) Minor street bicyclists must share the lane with right-turning vehicles in a channelized right-turn lane. Bicyclists, minor street movements Turning Motorists Crossing Bicycle Path (Section 4.4.18) Turning motorists cross the bike lane in this design with the development of the major street right-turn lanes. Bicyclists, major street through and left-turn movements Riding between Travel Lanes, Lane Additions, or Lane Merges (Section 4.4.19) The right-turn lane development requires bicyclists to travel between the through and right-turn lanes. Bicyclists, major street though and left-turn movements

Restricted Crossing U-Turn (RCUT) Intersections 7-19 minor street to continue directly into the storage bay for the U-turn crossover. The other option is to align it to the major street through lanes, with the U-turn crossover storage bay taper beginning farther downstream. If the U-turn crossover storage bay needs to extend back to the minor street, the first option (aligning the turn directly into the bay for minor street vehicles) is preferred. Exhibit 7-20 shows a signalized RCUT intersection with one of the two minor street lanes leading directly into the storage bay for the U-turn. Exhibit 7-21 shows a signalized RCUT intersection with two of the three minor streets lanes leading directly into the storage bay for the U-turn; in this case, a channelizing island separates the two lanes leading into the storage bay from the third right-turn lane. The tradeoffs of channelizing islands are noted above. Exhibit 7-19. Advantages and disadvantages of right-turn channelization. Advantages • Guides drivers more firmly, likely reducing sideswipe conflicts during the turn • Shortens pedestrian crossing distances to a refuge • Reduces the paved surface area • Provides the opportunity for a lane addition and a free right-turn (merge), reducing delay for that maneuver Disadvantages • Requires pedestrians to cross more vehicle pathways, with the right-turns moving faster and/or more freely; uncontrolled right-turns are more difficult to navigate for visually impaired pedestrians • Creates potential for uneven lane utilization on the minor street • Requires drivers on the minor street to select a lane earlier • Increases right-of-way to accommodate the channelization Exhibit 7-20. Schematic of RCUT intersection with one-lane, minor street approaches.

7-20 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 7.5.2 Traffic Control Devices 7.5.2.1 Pedestrian Signals Pedestrian signals at an RCUT intersection should be installed to accommodate a two-stage crossing, even if it is possible to make both major street crossings in a single stage. This is because pedestrians who are slower or faster than the design value for walking speed may get caught in the median with a red signal. This means a set of pedestrian signal heads, pushbuttons, and accessible pedestrian signals would be provided in the median for each crossing, as well as on the roadside. 7.5.2.2 Bicycle Signals Bicycle signals are used to direct and control bicycle movements that are atypical compared to conventional intersections and not concurrent with vehicle movements. Section 7.2.3 dis- cusses some options for the minor street through and left-turn movements by bicyclists, some of which involve passing through the channelizing island in the center of the main inter- section. Although there are no known installations, bicycle signals could be provided at an RCUT intersection for such movements. 7.5.3 Pedestrian Crossing Options Exhibit 7-22 shows a variation of the RCUT intersection design in which the minor street approaches are offset to allow a perpendicular pedestrian crossing of the major street. This has a minimal impact on vehicle operations at most RCUT intersections. A shorter crossing distance decreases pedestrian exposure to moving vehicles on the major street. Wayfinding signing and other devices would be needed to direct pedestrians to the crossing locations and deter them from crossing at the minor street intersections. This minor street offset design is typically not feasible where streets already exist, but in a developing area where the minor street or driveway locations have not been established, this variation may be considered. An advantage of the RCUT intersection, compared to many other at-grade intersections and arterials, is the flexibility for traffic signal placement on the corridor. Because each direction of travel on the arterial can operate independently (i.e., similar to individual one-way streets), negligible vehicle delay to major street vehicles results when installing additional traffic signals, as the signals can be timed to progress major street vehicles. This feature allows mid-block Exhibit 7-21. Signalized RCUT intersection with multiple lanes and channelization on the minor street.

Restricted Crossing U-Turn (RCUT) Intersections 7-21 pedestrian signals to be installed with minimal effect on vehicular travel time. Exhibit 7-23 shows two U-turn crossover configurations lending themselves to signalized mid-block pedes- trian crossings, including one where there are two U-turn crossovers near each other and one where there is only one U-turn crossover. If back-to-back U-turn crossovers are provided, as shown in Exhibit 7-23(a), these crossovers should be close to one another to facilitate pedestrian crossing and minimize out-of-direction travel for pedestrians. In the case of Exhibit 7-23(b), the signal controlling the eastbound traffic can be a specialized signal, such as a pedestrian hybrid beacon (PHB), to further minimize the effect on main street vehicle traffic. The pedestrian crossing of a three-legged RCUT intersection requires at least one mid-block crosswalk, as shown in Exhibit 7-24. The crossing route is direct. The optional second mid-block crosswalk, just beyond the U-turn crossover, would reduce out-of-direction travel for some pedestrians. Because it benefits pedestrians at a minimal cost and effect on major street vehicles, the second crossing should be strongly considered. Exhibit 7-22. RCUT intersection with minor street approaches offset to produce a shorter pedestrian crossing. Exhibit 7-23. Two types of signalized mid-block crossing feasible on RCUT corridor. (a, left) Two U-turn crossovers near one another. (b, right) single U-turn crossover.

7-22 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 7.5.4 Channeling Pedestrians to Crossing Wayfinding signing (and other wayfinding devices for the visually impaired) can help direct pedestrians through the intersection to their desired destinations. Adequate wayfinding signing and other devices help direct pedestrians unfamiliar with an RCUT intersection’s designated crossing patterns to cross streets at the appropriate locations. Channelization, such as curbs, railings, or landscaping, may help pedestrians locate and use intended crossing locations. However, choices of the channelizing devices or features should consider the proximity to traffic and appropriate roadside design principles. An example of a shared-use path across an RCUT intersection is shown in Exhibit 7-25. Exhibit 7-26 shows an example of a two-stage channelized pedestrian crossing at a conventional intersection in Tucson, Arizona. Similar to an RCUT intersection, each crossing operates independently to enable bidirectional progression on the corridor. 7.5.5 Crossings that Conflict with Minor Street Right-Turning Motorists Some RCUT intersection concepts include pedestrian crossings that cross the paths of right- turning motorists. These crossings have similarities to the minor street right-turn movements at MUT intersections (refer to Chapter 6 for further discussion of this condition). Treatments may include, but are not limited to, using exclusive pedestrian and bicycle phases, using leading pedestrian intervals equipped with accessible pedestrian signals, and restricting right-turns-on- red for motorists. Exhibit 7-24. Pedestrian crossing of three-legged RCUT intersection. Exhibit 7-25. Median shared-use path design for the U.S. Route 15/501 RCUT intersection in North Carolina.

Restricted Crossing U-Turn (RCUT) Intersections 7-23 7.6 References 1. Hummer, J., B. Ray, A. Daleiden, P. Jenior, and J. Knudsen. August 2014. Restricted Crossing U-Turn Informa- tional Guide. Report No. FHWA-SA-14-070. FHWA, Washington, DC. 2. United States Access Board. 2011. Proposed Guidelines for Pedestrian Facilities in the Public Right-of-Way (PROWAG). https://www.access-board.gov/guidelines-and-standards/streets-sidewalks/public-rights-of- way/proposed-rights-of-way-guidelines. Exhibit 7-26. Two-stage channelized pedestrian crossing at a conventional intersection.

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Alternative Intersections and Interchanges (A.I.I.s) are designs that improve operations and safety for motorized traffic by strategically adjusting the geometric features at a given location, working on the general principle of redistributing motor vehicle demand at an intersection in an attempt to limit the need to add capacity with new lanes to improve traffic flow.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 948: Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges provides specific guidance for four common A.I.I.s: Diverging Diamond Interchange (DDI), Restricted Crossing U-Turn (RCUT), Median U-Turn (MUT), and Displaced Left-Turn (DLT).

These designs may involve reversing traffic lanes from their traditional directions, which may introduce confusion and create safety issues for pedestrians and bicyclists. In addition, pedestrian paths and bicycle facilities may cross through islands or take different routes than expected. These new designs are likely to require additional information for drivers, bicyclists, and pedestrians as well as better accommodations for pedestrians and bicyclists, including pedestrians with disabilities.

NCHRP 20-44(35) is the implementation project for NCHRP Research Report 948. The implementation project's objective is to share and disseminate the research results with public agencies and provide hands-on technology transfer assistance to these agencies. Find project outcomes, including webinars and training materials, on the implementation project page.

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