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Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide (2023)

Chapter: Chapter 2 - RTOR and No Turn on Red Site Selection

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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
×
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
×
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
×
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Suggested Citation:"Chapter 2 - RTOR and No Turn on Red Site Selection." National Academies of Sciences, Engineering, and Medicine. 2023. Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/27131.
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CHAPTER 2 RTOR and No Turn on Red Site Selection 2.1 Introduction RTOR has been used in the United States for several decades. The main benefits of allowing RTOR movements are reductions in vehicular delays, queues, and fuel consumption. Several safety and operational considerations need to be evaluated before implementing RTOR operations. While the primary purpose of this document is to present information about RTOR models and to explain how they can be employed, information about RTOR site selection was also gathered during the course of this research. This chapter presents a synthesis of that information. 2.2  A Survey of RTOR Implementation Guidance To develop guidance on RTOR implementation, the research team consulted the literature on RTOR operation, as well as documents that are used to provide guidance on RTOR operations. From these the team synthesized a list of key considerations and identified those that are the most compelling, such as being mentioned in multiple resources. RTOR operation has been used throughout much of the United States since the 1970s, with the exception of a few citywide prohibitions. Prior to the 1970s, RTOR policies varied by region. The permissive right-turn rule was more common in western states, while prohibition of RTOR movements was more common in eastern states. Many jurisdictions prohibited RTOR operations because of safety concerns (Jaleel 1984). The situation changed with rising fuel prices in the 1970s. The 1975 Energy Policy and Con- servation Act required all states to adopt RTOR operations. This requirement was accompanied by a change to the Uniform Vehicle Code that generalized the rule of allowing RTORs whenever a No Turn on Red (NTOR) sign was not in place (with the exception of area-wide prohibitions, such as across cities). While motorists generally welcomed this change, pedestrians and urban traffic engineers worried about its effects on safety. Mamlouk et al. (1976) carried out one of the earliest RTOR studies. The researchers concluded that allowing RTOR operations would not have substantial adverse impacts on the safety of motorists and pedestrians. Reductions in vehicular and pedestrian delays were observed, and permission to execute the maneuver was favored by drivers. Some potential issues with RTOR identified by the researchers were that some drivers failed to come to a complete stop prior to executing the RTOR maneuver and that some drivers were confused about the maneuver or reluctant to carry it out (likely because the policy was then still new). The researchers suggested potential warrants for prohibiting RTOR, including the following: sites not having adequate sight distance to safely execute the maneuver, complex 3  

4   Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner’s Guide signal phasing, more than four legs at the intersection, short duration of the red interval, high volumes of conflicting traffic and pedestrians, low levels of right-turn demand, and the presence of school crossing routes. A decade later, concerns about RTOR safety were not fully resolved. A review of RTOR studies published in 1984 estimates that RTOR crashes likely increased all right-turn crashes by 23% while increasing pedestrian crashes by 60% and bicyclist crashes by 100% (Zador 1984). Their study compared overall crash rates in locations where RTOR was implemented compared to areas where laws did not change. This study did not examine crash severity but noted that the severity of the additional crashes attributed to RTOR were low. Chadda and Schonfeld (1985) performed an analysis of pedestrian safety performance relative to RTOR. The authors note that probable causes of pedestrian–vehicle RTOR accidents include “creeping” by motorists, difficulty observing pedestrians due to obstructions, driver error in execution of the RTOR maneuver, driver and pedestrian non-compliance with signal indica- tions, inadequate green light time for pedestrians, and inadequate enforcement. To help improve RTOR safety performance, Chadda and Schonfeld recommend removal of unwarranted traffic signals and the use of RTOR prohibition signs and angled stop bars. Non-engineering recom- mendations from Chadda and Schonfeld include incorporating RTOR regulations in driver education curriculum and driver licensing tests and implementing school safety education programs. (Note that more recent studies have shown school-based programs to have very limited effects.) The Energy Policy Act of 1992 directed NHTSA to carry out a study on the impact of RTOR on pedestrian safety. The researchers examined data from NHTSA’s Fatal Accident Reporting System (FARS) for the years 1989–1992 and state crash report data from Illinois, Indiana, Maryland, and Missouri. RTOR crashes represented about 0.05% of all crashes in the observed data, 0.06% of fatal and injury crashes, and 0.4% of all crashes at signalized intersections (NHTSA 1995). Although rare, RTOR crashes involved pedestrians or bicycles 22% of the time and 93% of the reported crashes resulted in injuries. Of fatal crashes, 44% involved a pedestrian, 10% a bicyclist, and 33% two vehicles. Although the 1995 NHTSA report concluded that few fatalities and injuries were caused by RTOR crashes, more recent studies have found major discrepancies between the number of pedestrian injuries reported by law enforcement and the number treated by hospitals (Oxley et al. 2018). Oxley’s group noted that police reports are typically created only if a driver is cited for a moving violation. In addition, they noted that pedestrians may underestimate the extent of their injuries at the time of the crash, resulting in a delay in seeking treatment and potential underrepresentation in police reports. Some studies have noted a risk to pedestrians from RTOR maneuvers. Retting et al. (2002) mention that RTOR vehicles do not always come to a full stop or may stop in locations that block pedestrian crossings. The RTOR maneuver requires drivers to look to the left for oncoming traffic, but a pedestrian could be crossing from the right, and drivers do not always remember to look to the right before starting to turn. Retting’s group compared the performance of condi- tional NTOR signs that prohibited RTOR when pedestrians were present or during certain times of day and concluded that the time-of-day prohibition was more effective. Design and operational guidelines for dual right-turn lanes were proposed in a technical report by Cooner et al. (2011). The researchers conducted a survey to collect information about design and operation of dual right-turn lanes. Total right-turn volume, traffic, and geometry of upstream and downstream intersections, turn bay length, design vehicle selection, intersection angle, sight distance, and intersection grade were listed as the major factors influencing design and operation of dual right-turn lanes based on survey responses. The researchers noted a

RTOR and No Turn on Red Site Selection   5   potential risk of crashes involving RTOR from the left lane of a dual right-turn lane group when the number of receiving lanes was more than two, and from both right-turn lanes when the downstream location had an entrance ramp nearby. Similar conclusions were drawn by Yi et al. in 2012. A study of 300 trips from the Second Strategic Highway Research Program (SHRP 2) Natural- istic Driving Study looked at detailed records of the driving behavior of 10 drivers at six inter­ sections (Wu and Xu 2017). The results showed that the average speed at the stop bar was 19 mph during a green light and 4.5 mph during a red light, while drivers turning on red exhibited higher acceleration. Lower acceleration was observed with multiple pedestrians as compared to a single pedestrian, demonstrating a potential effect of pedestrian conspicuity. In addition to the academic literature on RTOR, several policy documents and design guide- lines were consulted to discover other considerations for RTOR that may be of concern. These included the FHWA’s Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) (2009), several state manuals on traffic control devices, and other similar resources. A summary of the identified site considerations and the relevant sources is presented in Table 1. The development of this guidance comes at a time when many transportation agencies and policymakers are working to improve road safety. Unfortunately, in recent years, roads have become increasingly unsafe for pedestrians. The number of pedestrian fatalities increased by about 53% between 2009 and 2019, from 4,109 in 2009 to 6,272 in 2019 (IIHS HLDI 2020). Approximately 25% of pedestrian fatalities occurred at intersections in 2019. In 2020, the number of pedestrian deaths increased by the largest annual rate on record (GHSA 2021). It is beyond the scope of this document to evaluate the factors driving this increase in pedestrian fatalities, but the trends are worth considering in a discussion of RTOR policies. Table 1.   Site considerations influencing RTOR implementation. Site Considerations Sources MUTCD (FHWA) 2009, Chandler et al. Inadequate sight distance 2013, Minneapolis 2005, Mamlouk et al. 1976 Significant skew MUTCD (FHWA) 2009 MUTCD (FHWA) 2009, Minneapolis 2005, Uncommon geometrics or operational characteristics Mamlouk et al. 1976, and Schonfeld 1985 Exclusive pedestrian phase MUTCD (FHWA) 2009, Minneapolis 2005 Bicycle box NACTO 2011 School crossing route passing through the intersection Minneapolis 2005 Michigan Department of Transportation Railroad crossing and pre-signal in close proximity (MDOT) 2008, MDOT 2017 Dual RT lanes with more than two receiving lanes Chadda and Schonfeld 1985 Single receiving lane Mamlouk et al. 1976 MDOT 2008, MDOT 2017, Mamlouk et al. Safety concerns with right-turns and opposing left-turns 1976 High approach speeds Chadda and Schonfeld 1985 Excessive RTOR crashes per year MUTCD (FHWA) 2009, Minneapolis 2005 High number of pedestrian conflicts (especially children, elderly, MUTCD (FHWA) 2009, Chandler et al. disabled) 2013, AASHTO 2018, Mamlouk et al. 1976 Heavy cross street traffic for many hours Mamlouk et al. 1976 High U-turn volume Wisconsin DOT (WisDOT) 2019 Minneapolis 2005, Chadda and Schonfeld Poor compliance with NTOR and RTOR regulations 1985 Entrance ramp at the downstream location Chadda and Schonfeld 1985 Presence of a bus stop, taxi stand, or loading zone Chandler et al. 2013 WisDOT 2019, MDOT 2008, MDOT 2017, Unusual phasing Ontario Traffic Manual Committee 2000 Turning movement allowed from more than one lane on a specific Pennsylvania DOT (PennDOT) 2006 approach Dual opposing left turns PennDOT 2006

6   Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner’s Guide Pedestrian movement not in conflict because Don’t Walk is displayed Drivers looking toward this direction for oncoming Pedestrian movement in traffic conflict with RTOR RTOR Movement Figure 1.   Potential pedestrian conflict with RTOR. The results of most previous studies suggest that while RTOR increases the rate of right-turn crashes, RTOR is not a substantial contributor to fatal or injury crashes. These studies, mainly conducted between the mid-1970s and early 1990s, conclude that RTOR crashes represent small percentages of total crashes resulting in pedestrian fatalities or injuries. Thus, they predate efforts in the past few decades to build environments that promote walking and bicycling. In addition, the results need to be interpreted in the context of RTOR practice. Some cities, such as New York City, have long-standing RTOR bans, and many cities prohibit RTOR in areas with heavy pedestrian traffic or at specific intersections thought to be problem- atic. In October 2022, the Washington, D.C. Council voted to prohibit RTOR within the city by 2025, which would make it the second citywide ban in the United States after New York City. Previous research was mostly based on law enforcement crash report data, which is known to under-report non-fatal pedestrian crashes in comparison to data from emergency departments visits and hospital admissions (Oxley et al. 2018). At a typical signalized intersection, a RTOR movement crosses two pedestrian paths. The pedestrian movement parallel to the right-turn approach is likely to have a “Don’t Walk” indica- tion during the red light interval, while the pedestrian crossing perpendicular to the right-turn approach is likely to be serving pedestrian intervals. The safety of both pedestrian movements should be considered. There is a distinct danger if drivers executing the right turn are looking to the left for gaps in conflicting traffic when pedestrians are beginning to cross from the right (see Figure 1). Prohibiting RTOR is likely to be appropriate for intersection approaches, inter­ sections, or corridors where RTOR would exacerbate such conflicts. 2.3  Discussion of Site Considerations This section describes intersection site considerations that are relevant to RTOR operation. Several site considerations are discussed in turn, for which information or guidance for RTOR was found in the literature search in association with that condition. With some exceptions, most of the guidance that appears in literature is offered as a series of considerations for prohibiting RTOR, rather than absolute criteria for exclusion of a site. Thus, the decision of whether to allow or prohibit RTOR involves a degree of engineering judgment.

RTOR and No Turn on Red Site Selection   7   b Clear Sight Triangle a1 Decision Point Source: After AASHTO 2018. Figure 2.   Departure sight triangle for stop control. 2.3.1  Sight Distance Sight distance is one of the primary factors that needs to be considered in determining whether RTOR should be allowed at a signalized intersection. According to AASHTO’s A Policy on Geometric Design of Highways and Streets (the “Green Book”), the sight distance requirements for RTOR are the same as for two-way stop control (2018). An illustration of the sight triangle is shown in Figure 2. The distance a1 represents the measurement from the location where a driver decides to proceed to the center of the nearest destination lane. The distance b represents how far to the left the driver must be able to see to confirm that no conflicting traffic is traveling toward them. To determine b, the following equation for intersection sight distance (ISD) is used: ISD = 1.47 Vmajor t g (1) Here, Vmajor is the speed of the major road (mph), while tg is the gap time (s). The Green Book recommends the use of tg = 6.5 s for passenger cars, 8.5 s for single-unit trucks, and 10.5 s for combination trucks. The Green Book recommends adding 0.1 s for each percent greater than 0% for approaches where the upgrade is in excess of 3%. For example, if the upgrade is 2%, no additional gap time is added, but if the upgrade is 5%, tg is increased by 0.5 s. ISDs (for tg = 6.5 s) are provided in Table 2. Table 2.   ISD for right turn from stop. Stopping Sight Distance Intersection Sight Distance for Passenger Cars (ft) Design Speed (mph) (ft) Calculated Design 15 80 143.3 145 20 115 191.1 195 25 155 238.9 240 30 200 286.7 290 35 250 334.4 335 40 305 382.2 385 45 360 430.0 430 50 425 477.8 480 55 495 525.5 530 60 570 573.3 575 65 645 621.1 625 70 730 668.9 670 75 820 716.6 720 80 910 764.4 765 Source: AASHTO (2018).

8   Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner’s Guide PennDOT’s Official Traffic Control Devices publication (2006) provides minimum sight dis- tance requirements, indicating when a NTOR sign shall be used when the sight distance cannot be achieved (Table 3). The PennDOT document recommends measuring the sight distance from a point 10 ft upstream of a pedestrian crosswalk marking. In the absence of a pedestrian crosswalk, sight distance should be measured from a location 10 ft before the curb line or the edge of the cross street. The approaching vehicle and the position of the driver’s eyes are both assumed to be at a height of 3.5 ft. These distances are smaller than that yielded by the AASHTO formula and appear to be equal to the stopping sight distance on the major street rather than on the AASHTO ISD formula. Stopping sight distance (SSD) is given by: V 20 SSD = 1.47V0 t r + J a N (2) 30 KK ! GOO L 32.2 P where: V0 = speed of travel (mph); tr = reaction time (s); a = deceleration; and G = the decimal grade. For unexpected situations, tr = 2.5 s is used. Deceleration a = 11.2 ft/s2 is also commonly used. Solving this formula for various quantities of V0 and G yields the values in Table 3. It would appear that this policy considers whether drivers on the major street would be able to safely stop if another driver were to execute a right turn in front of them. The FHWA Signalized Intersections Informational Guide (Chandler et al. 2013) mentions that while measuring sight distance, an approximate height of 3 ft can be assumed both for the driver’s eyes and the approaching vehicle, and that the sight triangle can be obtained by connecting the decision point to the furthest point with unobstructed views along the conflicting approach. Visual obstructions such as trees, buildings, or parked vehicles should be considered. In traditional and neotraditional business and residential districts, building setbacks from the curb line are often only 4 to 12 ft, resulting in limited sight distance. For example, Figure 3 shows a skewed intersection where the southwest corner has a building separated from the edge of the road alignment by approximately 4 ft, making it difficult for Vehicle A to see approaching vehicles such as Vehicle B. Table 3.   PennDOT minimum sight distance requirements for RTOR. Sight Distance (Ft) Speed Limit Standard Approach Grade of the Crossing Street (Mph) Values –9% –6% –3% 3% 6% 9% 25 152 173 165 158 147 143 140 30 197 227 215 205 200 184 179 35 247 287 271 257 237 229 222 40 301 354 333 315 289 278 269 45 360 427 400 378 344 331 320 50 424 507 474 446 405 388 375 55 493 593 553 520 469 450 433 Note: Units in the source document are assumed to be in ft. Source: PennDOT 2006.

RTOR and No Turn on Red Site Selection   9   Source: Google Earth Figure 3.   Intersection approach where sight distance is restricted. The view to the left for the driver of Vehicle A is obscured by buildings on the southwest corner, making the RTOR potentially hazardous. Nevertheless, RTOR is often allowed in such areas. Factors such as prevailing traffic speeds, pedestrian volumes, right-turn demand, bus stop locations, and proximity to pedestrian traffic generators such as parks and elementary schools should be considered in decisions about whether to prohibit RTOR in these locations. 2.3.2  Intersection Skew Angle The FHWA Handbook for Designing Roadways for the Aging Population (Brewer et al. 2014) recommends prohibiting RTOR on a given approach when the intersection skew angle is less than 75 degrees. Skew angle may affect driver ability to look for oncoming traffic. However, sight distance is already a consideration, and it should include all approaches at all intersections regardless of skew. Another possibility is that intersections with high skew may make it more difficult for drivers executing the RTOR to transition from looking for oncoming vehicular traffic to looking at a pedestrian crosswalk they may be entering (as shown in Figure 1). However, consideration of the visibility of pedestrians should be considered at all intersections, not only those with high skew. For this reason, a separate criterion for intersection skew alone was not incorporated into the final guidance. 2.3.3  Number of Approaches Intersections having more than four approaches may pose a difficult scenario for motorists to execute RTOR maneuvers. At such intersections, motorists are more likely to have difficulty correctly identifying all traffic that conflicts with the RTOR movement, because there are more movements taking place overall and some traffic may be coming from an unexpected direction. There is also a possibility of downstream conflicts, because the RTOR motorist may be able to turn into more than one street. Mamlouk et al. (1976) recommend prohibiting RTOR at such intersections in general, but also noted that if there are adequate means of avoiding unexpected conflicts at such intersections, such as by channelization of turning movements, RTOR might be permitted.

10 Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner’s Guide 2.3.4 Pedestrian Phasing In the most common pedestrian phase configuration, the pedestrian “walk” and pedestrian change intervals occur simultaneously with a vehicular green in which the right turn is per- mitted, and right-turn vehicles are expected to yield to pedestrians. During the red interval for that vehicular movement, the pedestrians should see a “don’t walk” indication. Alternative phase configurations include: (1) exclusive pedestrian phases, (2) pedestrian overlaps, and (3) leading pedestrian intervals. Exclusive pedestrian phases provide a time period in the signal cycle where pedestrians can freely cross the intersection in any direction. At some sites this includes diagonal crossings. RTOR may be prohibited at such intersections to eliminate pedestrian–vehicular conflicts during the relevant pedestrian intervals. Pedestrian overlaps may be used at intersections with two-stage pedestrian crossings to allow the display of walk or pedestrian change concurrent with a shadowed left-turn movement. This shadowed left-turn movement is also an interval when RTOR is often possible because the left-turn movement blocks other vehicular traffic that would conflict with the right turn. RTOR may be prohibited at intersections with pedestrian overlaps to protect the pedestrian movements. A leading pedestrian interval (LPI) is a configuration where the walk display is illuminated a few seconds prior to the display of green for the concurrent vehicular movement. The objective is to permit pedestrians to enter the intersection prior to the start of green, making them more conspicuous to right-turn vehicles during green. Because there will be no conflicting traffic during the LPI, right-turning vehicles trying to execute a RTOR maneuver are more likely to perceive the LPI as an opportunity to carry out the turn, if they are unaware that the LPI is in operation. This is particularly problematic because the LPI encourages pedestrians to be in the crosswalk at the same time. Therefore, prohibition of RTOR is recommended at intersections with LPI to prevent right-turn vehicles from executing the turn during the LPI (Sharma et al. 2017). 2.3.5 Bicycle Boxes and Two-Stage Turn Queue Boxes As shown in Figure 4, a bicycle box is a designated area just upstream of the stop bar. During the red signal indication, bicyclists are able to pull in front of stopped motor vehicles, thereby increasing their visibility to drivers. The National Association of City Transportation Officials’ (NACTO’s) Urban Bikeway Design Guide (2011) recommends prohibiting RTOR at locations where bicycle boxes are used. Source: NACTO. Figure 4. Bicycle box.

RTOR and No Turn on Red Site Selection 11   Source: NACTO. Figure 5. Two-stage turn queue box in use at an intersection with a one-way street. Two-stage turn queue boxes are another feature to enhance bicyclist movement. Figure 5 shows an example implementation, with the dashed line indicating the bicycle left-turn movement and the solid line indicating the conflicting RTOR movement. Consider a bicycle on the approach coming from the left side of this image. If a bicyclist wishes to make a left turn, they can pull into the turn queue box and look for a gap in traffic before com- pleting the turn. The right-turn movement on the crossing approach would need to pass through the same space to execute the turn during red. The Urban Bikeway Design Guide (NACTO 2011) recommends prohibiting RTOR at locations where turn queue boxes are used. 2.3.6 Presence of Railroad Crossing, Light Rail, or Busway Near Intersection The presence of railroad crossings, light rail lines, or busways near an intersection influences the implementation of RTOR (Figure 6). Source: Google Earth. Figure 6. Light rail crossing at an intersection.

12   Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner’s Guide The PennDOT Official Traffic Control Devices manual states that when signal preemption is in use and right-turn vehicles cross an at-grade rail crossing within 200 ft of the intersection, “a part-time or intermittent prohibition of the turn-on-red movement may be used” (PennDOT 2006). MDOT recommends using a NTOR sign when a railroad crossing without a gate exists in close proximity to a signalized intersection, and the distance between the railroad crossing and the signalized intersection is not sufficient to store a design vehicle (MDOT 2008). Other factors that potentially merit consideration include the prevailing speeds on the roadway and railway, the horizontal and vertical geometrics of the crossing (such as skew, curvature, number of tracks, and elevation differences), the frequency of service on the rail line or busway, and the visibility of trains/buses to right-turning motorists (including the locations of signal masts and railroad signal controller “bungalow” cabinets). 2.3.7  Receiving Lanes Prohibiting RTOR from the rightmost lane of dual right-turn lanes should be considered when there are more than two receiving lanes (Figure 7). When the number of receiving lanes is more than two, right-turning vehicles may select an improper destination lane, leading to conflicts (Cooner et al. 2011). The 2009 MUTCD recommends using a sign reading “No Turn on Red Except from Right Lane” or “No Turn on Red From This Lane” placed over the center of the lane from which RTOR is prohibited (FHWA). In some states, RTOR is allowed only from the rightmost lane by law. When safety issues are apparent with RTOR and the opposing left turns, but a need for extra capacity exists, MDOT recommends using a dynamic blank-out “No Right-Turn-on-Red” sign (MDOT 2008). 2.3.8  Crash History An important factor that may warrant prohibiting RTOR at a signalized intersection is the number of RTOR-related crashes per year. The MUTCD recommends prohibiting RTOR movements at an approach when more than three RTOR-related crashes are reported in a 12-month period at that approach (FHWA 2009). Given that this may be a relatively high Source: Cooner et al. 2011, Texas Transportation Institute at Texas A&M University. Figure 7.   RTOR from dual right-turn lanes with more than two receiving lanes.

RTOR and No Turn on Red Site Selection   13   threshold to meet within 1 year, it may be advisable to review the crash history over a longer time period to identify a pattern. 2.3.9  Pedestrian Volume Moderate to high pedestrian volumes are a consideration for deciding whether to allow or prohibit RTOR. The right-turn vehicle path typically intersects the pedestrian paths and pro- hibiting RTOR would eliminate the potential conflict. Many cities have areas where pedestrian volumes are high, and such issues can also occur intermittently near land uses that attract large numbers of pedestrians such as conference centers or stadiums. Prohibition of RTOR may be necessary when a high number of pedestrian conflicts occur at an intersection involving children, elderly people, or people with disabilities. PennDOT’s Official Traffic Control Devices recommends restricting RTOR at such locations only during the time periods when significant conflicts occur between pedestrians and RTOR vehicles (PennDOT 2006). For example, if the conflict primarily involves children walking to school, RTOR might be prohibited only during the hours when large numbers of child pedestrians are present. 2.3.10  Conflicting Traffic Volume Another potential reason for prohibiting RTOR is when the conflicting traffic volume is typically very high over a long period of time, or when the crossing approach has significant U-turn volume. RTOR may be of little benefit due to insufficient gaps in the conflicting traffic (Mamlouk et al. 1976, WisDOT 2019). However, other times of day may exist when conflict- ing volumes are lower and RTOR would provide a benefit. The use of devices such as dynamic blank-out NTOR signs, or static signs conveying time-of-day restrictions, may be an option for such locations. 2.3.11  Downstream Ramps, Driveways, and Intersections For dual right-turn lanes, Cooner et al. (2011) recommend prohibiting RTOR from both lanes when an entrance ramp is located downstream from the intersection. Figure 8 illustrates the scenario, which is common for freeway frontage roads, as depicted by these authors. The concern seems to be not strictly the presence of the on-ramp, but of the need for the right-turn vehicle to weave across multiple lanes of traffic to reach the destination lane for the Source: After Cooner et al. 2011, Texas Transportation Institute at Texas A&M University. Figure 8.   RTOR with entrance ramp in close proximity.

14   Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner’s Guide ramp. For this reason, it seems appropriate to generalize the recommendation from ramps to any downstream destination (ramp, driveway, or intersection) that requires multiple lane changes. Cooner et al. (2011) recommend allowing RTOR if at least 250 ft per lane change exists between the intersection and the ramp. In such a scenario where right-turn vehicles seem likely to cross a large number of lanes to reach any destination at the far side of the street within a distance that is short in relation to the traffic speed, it may be prudent to disallow RTOR. 2.3.12  Bus Stops, Taxi Stands, Loading Zones, Etc. The presence of bus stops, taxi stands, loading zones, or other recurrent sources of standing traffic near an intersection may lead to blocking of the right-turn lane or bursts of pedestrian activity. If a bus stop or standing traffic is close to the intersection, the effects will be more prominent. Lane and shoulder width influence the extent to which standing vehicles block traffic. Bus frequency and passenger loads also affect these circumstances. 2.3.13  Safe System Approach In recent years, the concept of a Safe System Approach has attracted increasing attention. The U.S. Department of Transportation (DOT) (2022) characterizes the Safe System Approach as having the following principles: • Death and serious injuries are unacceptable. The goal is to eliminate crashes that result in these outcomes. • Humans make mistakes. The transportation system must be able to accommodate certain types of mistakes. • Humans are vulnerable. Systems must be designed and operated to accommodate the limits of the human body. • Responsibility is shared. All stakeholders in the system have a role in achieving safe road operation. • Safety is proactive. Action should be taken before rather than after crashes occur. • Redundancy is crucial. Systems must be designed such that if one part fails, another part is able to offer protection. Examples of treatments from a safe systems perspective are presented by Naumann et al. (2020). These examples include the separation of conflicting movements in time and space, and restriction of RTOR increases the amount of separation. Another principle is simplicity, such as limiting turning maneuvers. The RTOR movement can be complex since the driver must potentially negotiate multiple streams of traffic, including conflicting vehicular traffic approach- ing from the left, while pedestrians may be present to the right. There are several arguments that could be made against RTOR from the perspective of proactively eliminating crashes. At the same time, however, little evidence was found in the literature search to indicate that RTOR is likely to induce severe crashes. With the increasing adoption of the safe systems approach, RTOR may be reevaluated for some locations in future. 2.4 Summary of Considerations for RTOR Site Selection The criteria reviewed in this chapter are summarized in Table 4. Each item lists an aspect of intersection operation that would tend to favor allowing or prohibiting RTOR. Most of these criteria require application of engineering judgment, and each criterion is a candidate for further study to develop more precise recommendations. For example, the sight distance

RTOR and No Turn on Red Site Selection   15   Table 4.   Summary of considerations for RTOR site selection. Criterion Description RTOR Consideration Adequate sight distance is required for right-turn Prohibit RTOR if the right-turn drivers to be able to see all conflicting streams of Sight distance movement has inadequate sight traffic (vehicle, pedestrian, bicycle, and any other distance. mode). Some intersection geometries make it difficult for right-turn drivers to judge the path of conflicting Prohibit RTOR if intersection geometry Complex traffic, even if there is adequate sight distance. For would make it difficult to determine the geometry example, intersections with more than four legs may path of potentially conflicting traffic. have such issues. Prohibition of either the RTOR or the The subject right turn movement has a shadowed left Heavy U-turn U-turn would resolve the conflict. Use turn that includes a large amount of U-turn traffic traffic of a blank-out NTOR sign and/or that would conflict with the right turn traffic. overlap may also resolve. The cross street carries high-speed traffic, making it difficult for entering vehicles to attain that speed, or Consider prohibiting RTOR at Heavy crossing encouraging drivers to heavily accelerate when crossings with high-speed major streets street speed executing the turn, potentially increasing risk to if there is a potential for such conflicts. crossing pedestrians. Prohibition of RTOR may be able to Are right-turning vehicles unlikely to cross several Driver destination resolve such conflicts. Use of lanes of traffic to reach a destination on the far side after turn channelization and access management of the crossing street? may also resolve. Bicycle boxes (Figure 4) and turn queue boxes for Bicycle boxes and Consider prohibiting RTOR if the bicyclists (Figure 5) occupy the intersection space turn queue boxes right-turn path goes through such areas. needed for the RTOR movement. Roadside areas/uses such as transit facilities, Transit and curb rideshare facilities, or other loading/unloading areas, Consider prohibiting RTOR if the activities may induce additional conflicts from the vehicles right-turn path would interfere with participating in these activities or from pedestrians transit or other curbside activities. and other modes involved. Exclusive pedestrian phases and leading pedestrian RTOR would typically be prohibited intervals are intended to improve service of with the use of exclusive pedestrian Special pedestrian pedestrians. During such intervals, conflicting phasing or leading pedestrian intervals. phases vehicle traffic is reduced, so RTOR vehicles may be Use of blank-out NTOR signs could encouraged to execute the turn but may conflict with resolve for locations with dynamic the pedestrians. conditions. The site is used by more vulnerable pedestrian Vulnerable Consider prohibiting RTOR at groups, such as school children, elderly and disabled pedestrians locations with vulnerable pedestrians. persons, etc. The site is used by large numbers of pedestrians at Consider prohibiting RTOR at Large numbers of times, especially if there is no special treatment for locations with large numbers of pedestrians pedestrians. pedestrians. The site has a history of crashes involving RTOR Consider prohibiting RTOR at Historical vehicles, conflicts, or generates a large number of locations exhibiting a record of performance public complaints about vehicles failing to yield. problems related to RTOR. criteria are the most critical, but variations in methods for evaluating the sight distance could influence the outcome. This summary should be seen as an overview of items that have been noted in the literature as worth consideration more than a rubric for decision-making at a particular site. However, the likelihood of driver compliance with a NTOR sign should also be considered. Posting of a NTOR sign may not resolve the problem if there are other issues. This table could be used to develop further guidance on site selection for RTOR that could be incorporated into other reference documents for traffic signal control. For example, NCHRP Report 812 (Urbanik et al. 2015) does not presently include specific RTOR guidance. A model for how such guidance could be provided may be found in the presentation of alternative left- turn treatments (see Exhibit 4-16 in NCHRP Report 812). The exhibit provides suggested left-turn phase options (protected, permitted, or protected/permitted) using a decision-tree structure for 12 input questions.

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Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide Get This Book
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There is a need for improved techniques for estimating the performance of right-turn-on-red (RTOR) movements at signalized intersections.

NCHRP Research Report 1068: Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide, from TRB's National Cooperative Highway Research Program, presents two methods for estimating RTOR volume and capacity, and a spreadsheet tool to facilitate the use of these methods. The report also presents guidance on when to prohibit RTOR at a given intersection.

Supplemental to the report is NCHRP Web-Only Document 368: Right-Turn-on-Red Operation at Signalized Intersections with Single and Dual Right-Turn Lanes: Evaluating Performance, a presentation, a spreadsheet tool, and a Computational Engine with RTOR.

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