Design Guidance for Channelized Right-Turn Lanes (2014)

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Channelized right-turn lanes with yield control were shown to reduce right-turn delay to vehicles by 25 to 75 percent in comparison to intersection approaches with conventional right- turn lanes. High pedestrian volumes increased right-turn delay by approximately 60 percent on a yield-controlled channelized right-turn lane. The addition of an acceleration lane at the downstream end of a channelized right-turn lane can reduce the right-turn delay by 65 to 85 percent, depending on the conflicting traffic volume on the cross street. Increasing the radius of a channelized right-turn roadway can reduce right-turn delay by approximately 10 to 20 percent for each 8-km/h (5-mi/h) increase in turning speed. Seven (7) years of motor-vehicle and pedestrian crash and volume data were obtained for 103 four-leg signalized intersections in Toronto, Ontario, Canada. An overall comparison was performed of the safety performance of intersection approaches with channelized right-turn lanes to intersection approaches with other right-turn treatments. Specifically, a cross-sectional analysis was conducted to compare the crash experience among: • Intersection approaches with channelized right-turn lanes • Intersection approaches with conventional right-turn lanes • Intersection approaches with no right-turn treatments (shared through/right-turn lanes) Intersection approaches with channelized right-turn lanes were shown to have similar motor- vehicle safety performance as approaches with conventional right-turn lanes or shared through/right-turn lanes where the right-turning vehicle departs from the through traffic stream (the upstream end of the channelized right-turn lane). Results of the safety analysis suggest that the three right-turn treatments may differ in motor-vehicle safety performance as the right- turning vehicle merges with the cross street (the downstream end of the channelized right-turn lane), but this was not conclusively established. Intersection approaches with channelized right- turn lanes were shown to have similar pedestrian safety performance as approaches with shared through/right-turn lanes. Intersection approaches with conventional right-turn lanes had substantially more pedestrian crashes (approximately 70 to 80 percent more) than approaches with channelized right-turn lanes or shared/through right-turn lanes. A recommendation of the research is for highway agencies to develop a consistent practice for crosswalk location. Consistency in crosswalk location is important to pedestrians with vision impairment and would make it easier for O&M specialists to teach pedestrians with vision impairment how to better traverse a channelized right-turn lane. Since current practice shows a clear preference for crosswalk locations near the center of a channelized right-turn lane, design guidance should recommend placing crosswalks near the center of the channelized right-turn lane for channelized right-turn lanes with yield control or no control at the entry to the cross street. Where STOP sign control or traffic signal control is provided at the entry to the cross street, the crosswalk should be placed immediately downstream of the stop bar, where possible. Where the channelized right-turn roadway intersects with the cross street at nearly a right angle, the stop bar and crosswalk can be placed at the downstream end of the channelized right-turn roadway. ix

Raised islands should be considered because they serve as a refuge area so that pedestrians may cross the street in two stages. Raised islands with “cut-through” paths also provide better guidance for pedestrians with vision impairment than painted islands. Channelized right-turn lanes with acceleration lanes appear to be difficult for pedestrians with vision impairment to cross. Therefore, the use of acceleration lanes at the downstream end of a channelized right-turn lane should generally be reserved for locations where no pedestrians or very few pedestrians are present. Typically, these would be locations without sidewalks or pedestrian crossings; at such locations, the reduction in vehicle delay resulting from addition of an acceleration lane becomes very desirable. Channelized right-turn lanes are most appropriate for improving traffic operations at intersections where pedestrian volumes crossing the channelized right-turn lane are expected to be low to moderate (e.g., up to approximately 1,000 pedestrians per day). This recommendation is based on the 85th percentile pedestrian volume—1,000 pedestrians per day—in the Toronto intersection database that was used for the safety evaluation. While channelized right-turn lanes may be suitable for higher pedestrian volumes, the research cannot predict the safety performance of channelized right-turn lanes with pedestrian volumes beyond the range evaluated in the research. The research results indicate that channelized right-turn lanes have a definite role in improving operations and safety at intersections. However, to achieve these benefits they should have consistent design and traffic control and should be used at appropriate locations. The research provides design guidance for channelized right-turn lanes that addresses geometric elements such as crosswalk location, special crosswalk signing and marking, island type, radius of turning roadway, angle of intersection with cross street, acceleration and deceleration lanes, and traffic control. x

Chapter 1. Introduction This chapter summarizes the background for the research, the research objectives and scope, and the organization of this report. Background 1.1 Channelized right-turn lanes are turning roadways at intersections that provide for free-flow or nearly free-flow right-turn movements. Channelization can be provided in a variety of forms including painted pavement areas and curbed islands. Figure 1 illustrates an intersection with channelized right-turn lanes. While the figure shows channelized right-turn lanes in all quadrants of the intersection, channelized right-turn lanes may be appropriate in some quadrants, but not in others, depending on intersection geometry and traffic demands. Figure 1. Typical Intersection with Channelized Right-Turn Lanes The primary reasons for providing a channelized right-turn lane are (1): • To increase vehicular capacity at intersections • To reduce delay to drivers by allowing them to turn at higher speeds • To reduce unnecessary stops Channelized right-turn roadway Channelizing island Channelized roadway width Radius 1

• To clearly define the appropriate path for right-turn maneuvers at skewed intersections or at intersections with high right-turn volumes • To improve safety by separating the points at which crossing conflicts and right-turn merge conflicts occur • To permit the use of large curb return radii to accommodate turning vehicles, including large trucks, without unnecessarily increasing the intersection pavement area and the pedestrian crossing distance Many transportation agencies use channelized right-turn lanes to improve operations at intersections, although their impact on safety for motorists, pedestrians, and bicyclists has not been clear. A key concern with channelized right-turn lanes has been the extent of conflicts between vehicles and pedestrians that occur at the point where pedestrians cross the right-turn roadway. Conflicts with pedestrians may occur at right-turn roadways because the driver's attention may be focused on the cross-street traffic; the placement of pedestrian crosswalks or pedestrian signals on channelized turning roadways may violate driver expectancy. For most pedestrians, crossing the right-turn roadway is a relatively easy task because such roadways are not very wide and because traffic is approaching from a single direction. However, pedestrians with vision impairment may have difficulty detecting approaching traffic because (a) right-turning vehicles are traveling a curved rather than a straight path; (b) there is not a systematic stopping and starting of traffic, as there would be at a conventional signal- or stop- controlled intersection; and (c) the traffic sounds from the major streets may mask the sound of traffic on the right-turn roadway. The Americans with Disabilities Act (ADA) requires that all pedestrian facilities, including sidewalks and crosswalks, be accessible to pedestrians with disabilities. The U.S. Access Board has published draft rights-of-way guidelines requiring pedestrian-activated signals at multi-lane crossings of channelized right-turn lanes with pedestrian signal indications (2). Specifically, it states: “R305.7 Channelized Turn Lanes at Intersections. Where pedestrian crosswalks are provided at multi-lane right or left channelized turn lanes at intersections with pedestrian signal indications, a pedestrian-activated signal complying with R306 shall be provided. Advisory R305.7 Channelized Turn Lanes at Intersections. Accessible pedestrian signal devices installed at splitter and ‘pork chop’ islands must be carefully located and separated so that signal spillover does not give conflicting information about which crossing has the WALK indication displayed. Additional guidance on signal types is provided in Advisory R305.6.2.” Despite their potential challenges for pedestrians, channelized right-turn lanes also provide advantages for pedestrians. The provision of a channelized right-turn lane, while making it necessary for pedestrians to cross two roadways, often reduces the pedestrian crossing distance of the major and cross streets. Furthermore, the channelizing island serves as a refuge area for pedestrians, particularly when bounded by raised curbs, and improves safety by allowing pedestrians to cross the street in two stages. 2

The primary traffic operational reasons for providing channelized right-turn lanes are to increase vehicular capacity at an intersection and to reduce delay to drivers by allowing them to turn at higher speeds and reduce unnecessary stops. Channelized right-turn lanes appear to provide a net reduction in motor vehicle delay at intersections where they are installed, although no existing data and no established methodology have been available to directly compare the operational performance of urban intersections with and without channelized right-turn lanes. Furthermore, no data are available on the operational effects of installing pedestrian-activated signals along right-turn roadways. The safety effects of channelized right-turn lanes on motor vehicles, pedestrians, and bicyclists have been largely unknown. It is generally accepted that channelized right-turn lanes improve safety for motor vehicles at intersections where they are used, but there have been only limited quantitative data to demonstrate this. No studies have been found concerning pedestrian safety at channelized right-turn lanes that have used crash data to document the pedestrian safety implications of channelized right-turn lanes. There also appears to be an inherent risk to bicyclists at channelized right-turn lanes because motor vehicles entering the channelized right- turn roadway must weave across the path of bicycles traveling straight through the intersection, but no studies based on crash history are available to support this presumption. However, this same type of conflict between through bicyclists and right-turn vehicles is present at conventional intersections as well. It is evident that there have been many unanswered questions about channelized right-turn lanes. The research conducted for this report sought to answer many of these questions and to provide a basis for decisions, based on sound research results rather than anecdotal evidence, about where channelized right-turn lanes should and should not be used. Research Objectives and Scope 1.2 The objective of the research was to develop design guidance for channelized right-turn lanes, based on balancing the needs of passenger cars, trucks, buses, pedestrians (including pedestrians with disabilities), and bicycles. For the purposes of this project, a channelized right- turn lane is characterized by separation from the through and left-turn lanes on the approach by an island and separate traffic control from the primary intersection. The channelized right-turn lane may have a deceleration lane entering it and it may have a merge or an auxiliary lane at the exiting end. The results of the research include general design guidance on channelized right-turn lanes for highway engineers and specific recommended language for consideration in future updates to key AASHTO and FHWA documents. Organization of This Report 1.3 This report presents the results of the research on channelized right-turn lanes. The remainder of this report is organized as follows. Chapter 2 presents an overview of the state of knowledge and practice with channelized right-turn lanes, based on a review of literature and a 3

survey of highway agency experience. Chapter 3 discusses pedestrian behavior at channelized right-turn lanes based on observational field studies and interviews with orientation and mobility specialists. Chapter 4 presents the results of a traffic operational analysis of channelized right- turn lanes. Chapter 5 presents the results of a safety analysis of channelized right-turn lanes. Chapter 6 presents the interpretation of the research results. Chapter 7 presents the conclusions and recommendations of the research. Chapter 8 presents a list of references cited in this report. Appendix A includes a design guide for channelized right-turn lanes. Appendix B presents suggested text concerning channelized right-turn lanes for consideration by AASHTO for potential inclusion in future editions of the Green Book. 4