Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook (2017)

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48 C H A P T E R 5 The Green Book defines channelization as “the separation or regulation of conflicting traffic movements into definite paths of travel by traffic islands or pavement marking to facilitate the orderly movement of both vehicles and pedestrians.” NCHRP Report 279 presents nine principles of channelization, one of which is that channelization can provide refuge for non-motorized users. For purposes of this project, CTLs are defined as right-turn lanes having raised islands separating them from other lanes at an intersection. Oftentimes, CTLs are installed for geometric reasons, and particularly to accommodate design vehicles at skewed intersections. In other cases, CTLs are used to increase the capacity for right- turning traffic. Recent research (Potts et al., 2011) found that CTLs had a lower motor vehicle crash frequency than conventional right-turn lanes and higher motor vehicle crash frequency than shared right- through lanes. In other words, once a decision has been made that a designated right-turn lane is needed for capacity, a CTL provides a safer configuration than an exclusive right-turn lane without channelization. Figure 5-1 depicts these three types of right-turn lanes. The effects of CTLs on pedestrian safety have historically been poorly documented. To date, the largest study of pedestrian safety at CTLs analyzed data from 400 intersection approaches in Toronto (Potts et al., 2011). The study found that pedestrian crash frequency was approximately the same on approaches with CTLs and approaches with shared through-right lanes. Approaches with con- ventional right-turn lanes had 70% to 80% more pedestrian crashes. These findings, coupled with the auto safety findings noted earlier, suggest that where right-turn lanes are needed for capacity purposes, it may be appropriate to channelize them even if pedestrian activity is anticipated. However, as emphasized in Chapter 1.2, pedestrian safety and accessibility are two different questions, and while safety performance is important, the focus of this document is on the acces- sibility performance of CTLs. Advantages and disadvantages of CTLs for pedestrians compared to conventional right-turn lanes are presented in Table 5-1. Some of the design elements of CTLs that are advantageous for pedestrians in general are problematic for blind pedestrians. For example, the benefit of a refuge island is offset by the navigational and wayfinding tasks that must be performed to reach the island and subsequently leave it. The curved nature of CTLs makes it more challenging for blind pedestrians to locate crosswalks, remain in crosswalks, hear vehicles, know if their crossing is controlled by a signal or not, and know when they have reached the other side of the street. The typical lack of signaliza- tion for the CTL requires that blind pedestrians base decisions about when to begin crossing on acoustic information about gaps in traffic and yielding vehicles. These challenges are similar to the challenges that blind pedestrians face at roundabouts (see Chapter 3). Design Principles for Pedestrian Access at Channelized Turn Lanes

Design Principles for Pedestrian Access at Channelized Turn Lanes 49 5.1 Geometric Design This chapter presents the proposed best practices for the design of CTLs, applying the way- finding and crossing tasks discussed in Chapter 3, to specific applications at CTLs. CTLs generally have been designed in accordance with best practices and agency preferences rather than a performance-based approach as is used with roundabouts. However, while this design process is less formalized than for roundabouts, the same performance-based principles are adopted for CTLs. This chapter presents key design elements and associated best practices. Two elements of design of particular importance to blind pedestrians—traffic control devices and crosswalk location—are discussed in detail later. (a) (b) (c) Figure 5-1. Types of right-turn lanes. Figure 5-1 shows three similar intersections. Figure 5-1(a) has a dedicated right-turn lane that is channelized on the northbound leg with an island separating it from the adjacent through lane. Figure 5-1(b) has a single northbound lane that is used by right-turning drivers and through drivers. Figure 5-1(c) has a dedicated right-turn lane on the northbound leg; it is not physically separated from the adjacent through lane. Advantages Disadvantages Island serves as a refuge for pedestrians. Compared to crossings having a conventional right-turn lane, the length of the main crosswalk is shorter. Right turn on red maneuvers are removed from the main crosswalk spanning through and left lanes. Right turn on green maneuvers are removed from the main crosswalk spanning through and left lanes. Larger turn radii can decrease the likelihood of large vehicles encroaching or off-tracking onto sidewalks. In most cases, the crossing of the CTL is unsignalized. Pedestrians must make decisions about the speed of vehicles and driver yielding behavior Channelization may enable higher speeds for right-turn vehicles Curvature of the channelized lane may create sight distance and visibility issues for drivers and pedestrians. Crosswalk location varies and angles may be confusing for pedestrians with vision disabilities. Drivers may be focused on conflicting traffic and searching for gaps rather than focusing on pedestrians. Table 5-1. Advantages and disadvantages of CTLs for pedestrians.

50 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook 5.1.1 Island Design Section 9.6.3 of the Green Book provides guidance on island design. Islands should be a mini- mum of 50 ft2 in urban areas and 75 ft2 in rural areas, to assure that the island is readily visible to approaching drivers. Additional considerations for island size include expected storage space, especially if frequent use by (groups of) pedestrians and bicycles is expected. An example of an island barely large enough to accommodate two cyclists and a pedestrian on roller skates is shown in Figure 5-2. The leading and trailing ends of the island should be designed in accordance with principles of channelization shown in Figures 9-38 and Figure 9-39 of the Green Book. The same principles discussed in the design of splitter islands at roundabouts apply to the channelization islands at CTLs. Pedestrians who are blind or who have low vision need appropriate guidance through the island area to the other crosswalks from the island. A completely paved island with no landscap- ing materials present in areas adjacent to the crosswalk can be disorienting, as was observed at several sites studied in this research (see Figure 5-3). In addition and as noted earlier, detectable warning surfaces must be provided at the boundary between the island and the street to alert individuals to the location of the street or island boundary. The general design principles for CTL islands are similar to roundabouts, and the principles discussed in Chapter 4.1 generally apply to CTL islands as well. Desirable design dimensions for CTL islands are illustrated in Figure 5-4. Similar to roundabouts, the area outside the prescribed path on CTL islands should be detectable as a non-walking surface. Research has shown that some participants were slightly misaligned when crossing and reached the island outside the crosswalk area (NCHRP Proj- ect 03-78B). When reaching the island, individuals who were blind were typically taught to step up onto the island to get out of the street as quickly as possible rather than to look for a cut- through area or curb ramp. If the island was grass or an obvious non-walking surface such as Figure 5-2. A crowded CTL island with pedestrians and bicycles. Figure 5-2 shows an island with two cyclists and a pedestrian on roller skates. One of the bicycles has a trailer attachment, and the island is barely large enough to accommodate it.

Design Principles for Pedestrian Access at Channelized Turn Lanes 51 (a) (b) Figure 5-4. Minimum CTL island and crosswalk dimensions. Figure 5-4(a) shows a 5 ft minimum width of the crosswalk with a cut-through pedestrian path. Within the cut- through area of the island for the full width of the cut-through is a 2 ft section of detectable warning surface, then at least 2 ft of smooth surface, and then another 2 ft section of detectable warning surface. The actual separation between the two detectable warning surfaces is significantly larger on this island. Figure 5-4(b) shows an island with ramps sloping up on each side with detectable warning surfaces at the base of the ramps at each street edge. A 4 ft level landing between the ramps is required, although the area in the figure is significantly larger than that. Figure 5-3. Blind pedestrian disoriented on an all-paved CTL island. Figure 5-3 shows a blind pedestrian (followed closely by an orientation and mobility specialist) on an all-paved island, approaching the curb near the end of the island, not at the crosswalk.

52 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook pebbles, they tended to look for and found the paved path or cut-through area. Figure 5-5 shows an example with gravel treatment outside the intended walking area, and other examples exist with grass or landscaping on the islands. When the entire island was raised but had a concrete or brick surface, blind pedestrians were often unable to reorient or maintain their orientation in crossing the island (see Figure 5-3). If the island had a cut-through pedestrian path, they were unable to discern whether the cut- through was the pedestrian path or the street, causing further disorientation and failure to locate the crosswalk to complete crossing the street. 5.1.2 Radius of the Turning Roadway The radius of the turning roadway in a CTL is a function of turning speeds, truck consid- erations, pedestrian crossing distances, and island sizes. In locations where pedestrians are expected, the radius of the turning roadway should be minimized. This reduces vehicle speeds and has been shown to increase yielding to pedestrians by drivers (Potts et al., 2011). 5.1.3 Angle of Intersection with the Cross Street The Green Book historically recommended that CTLs be designed with flat angle entries to the cross street, as shown in Figure 5-6(a). This design may be appropriate at CTLs without pedes- trian facilities, and with yield control or no control and an acceleration lane (Potts et al., 2011). However, where pedestrians are expected to cross the CTL, a design similar to the one in Figure 5-6(b) is preferred. This guidance is also consistent with the guidance provided in the Guide for the Planning, Design and Operation of Pedestrian Facilities (AASHTO, 2004). The “pork chop” or “lamb chop” island design shown Figure 5-6(b), provides improved sight distances between the pedestrian and approaching vehicles, and further is likely to enhance the vis- ibility of traffic control devices at the crosswalk. The design is generally believed to result in slower vehicle speed than Figure 5-6(a), although the actual design speed depends on the geometry and curve radii used. Islands and CTLs should be designed to encourage slow vehicle speeds, minimize the need of drivers to turn their heads far to the left, and place the pedestrian crossing point before Figure 5-5. Island with ramps to paved walkways and gravel outside the pedestrian path area. Figure 5-5 shows an island with detectable warning surfaces along the edge of the island and wide paved paths across the island in two directions: to the two main street crossings, with a bench along the path as well. Outside the path area, the surface of the island is crushed stone.

Design Principles for Pedestrian Access at Channelized Turn Lanes 53 the downstream yield point for vehicles. This last feature separates driver decisions of interact- ing with pedestrians (yielding) and interacting with the downstream traffic stream (searching for gaps). Similar to the placement of crosswalks at roundabouts, crosswalks at CTLs should be placed one-vehicle length back from the downstream yield line for vehicles for that reason. 5.1.4 Deceleration and Acceleration Lanes Use of a deceleration lane is often advantageous for a safe crossing environment to slow vehi- cles before they enter the CTL, reduce the speed differential between right-turning traffic and the traffic on the downstream through lanes on the entering roadway, and reduce the likelihood of queues blocking the entrance to the CTL. This may also make it easier for blind pedestrians to detect a vehicle in the lane approaching the crosswalk. Use of acceleration lanes should be avoided at locations where pedestrians are expected, because they are believed to increase vehicle speeds and decrease yielding. 5.1.5 Sight Distance and Visibility Stopping sight distance values for CTLs are the same as the values for an open highway, and are presented in Table 9-21 of the Green Book. At all points along a CTL, visibility to the downstream roadway and any crosswalks should be available. 5.1.6 Design Vehicle Accommodation Figure 9-43 and Table 9-18 of the Green Book provide edge of way designs for different vehicles and two types of curves: simple curve radius with taper and three-centered curves. For situations (a) (b) Figure 5-6. Typical CTLs with different entry angles to the cross street. Figure 5-6 shows two types of angles and curvatures for a CTL. In Figure 5-6(a), the lane turns to the right continu- ously and vehicles are nearly parallel with the downstream roadway at the end of the CTL, creating a very flat-angle entry to cross the street. In Figure 5-6(b), the CTL diverges from the entering, and vehicles are nearly perpendicular to the downstream roadway at the end of the CTL.

54 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook in which other types of curves are used or roadways that do not intersect at a right angle, software- generated vehicle turning templates can be used to determine the necessary edge-of-traveled-way designs. 5.1.7 Crosswalk Location and Angle Options The geometric design of a crosswalk can directly influence its effectiveness, regardless of the type of traffic control devices used at that crosswalk. Guide for the Planning, Design and Operation of Pedestrian Facilities (AASHTO, 2004) provides criteria that pedestrian crossings to triangular islands should meet: 1. Pedestrian crossings should be at 90 degrees across the turn lane and be placed where the motorist can easily see the pedestrian crossing ahead; 2. Pedestrians and motorists must be able to easily see each other; and 3. The design should encourage low vehicle turning speeds (Potts et al., 2011). For CTLs, the first and second objectives are sometimes in conflict. A crosswalk that is 90 degrees across the turn lane (perpendicular to a tangent of the turn lane) may be too far downstream in the CTL where the line of sight and visibility are compromised. Generally, the use of a larger island with a pork chop design is more likely to provide adequate space to properly locate the pedestrian crossing to meet both objectives. For smaller islands, the crosswalk may need to be angled at more than 90 degrees, which is less desirable. Also, NCHRP Project 03-78B found that it is critical for the crosswalk to reach the island in a “centered” location, which provides sufficient island surface area on the left and right side of where the crosswalk meets the islands. For crosswalks too close to either edge of the island, blind pedestrians were observed to sometimes miss the island entirely, and walk into the main travel lanes. The third objective of low turning speed may conflict with the need to accommodate for a specific design vehicle. But even for large design vehicles, the CTL design and crosswalk location should aim to achieve slow speeds in the vicinity of the crosswalk. NCHRP Web-Only Docu- ment 208 discussed five options for crosswalk placement and alignment at a CTL, which have been re-ordered here, starting with the most preferred option based on this research. These pos- sible configurations are shown in Figure 5-7. • Option 1. At the center, and perpendicular to the sidewalk and CTL; • Option 2. At the upstream end, and parallel to the entering road; • Option 3. At the upstream end, and perpendicular to the sidewalk and CTL; • Option 4. At the downstream end, and parallel to the exiting road; or • Option 5. At the downstream end, and perpendicular to the sidewalk and CTL. When choosing a configuration, there are several conflicting challenges to balance from a pedestrian perspective: • The crosswalk should be located conveniently close to non-channelized lanes and their crosswalks to minimize out-of-direction travel for pedestrians. Pedestrians are increasingly likely to cross closer to the parallel street if the designated crossing location is too far out of their direction of travel, if insufficient channelization is provided to encourage crossing at the appropriate location, and if the pedestrian does not perceive a risk of crossing away from the desig- nated location. This can be particularly problematic for larger turning radii associated with a flatter-angle entry CTL. A centered crosswalk is likely to balance out-of-direction travel for pedestrians approaching from different directions. • The crosswalk should minimize crossing distances and thereby exposure to traffic in the CTL. In general, a crosswalk close to a 90-degree angle across the turn lane will result in the shortest

Design Principles for Pedestrian Access at Channelized Turn Lanes 55 crossing. AASHTO recommends that pedestrian crossings should be placed at a 90-degree angle across the CTL and located so that pedestrians and drivers can see one another (AASHTO, 2004). Crossings at a 90-degree angle also minimize the crossing distance and thus reduce exposure. They also enable curb ramps to be both perpendicular to the sidewalk and aligned with the crosswalk, thus benefitting both pedestrians who use wheelchairs and pedestrians who are blind. • Good visibility of conflicting vehicle traffic needs to be provided to allow pedestrians to detect gaps. Having good visibility is oftentimes correlated with an improved audible environment. A crosswalk located toward the downstream end of the CTL is less likely to have good visibility and audibility. • Positive wayfinding guidance to the crosswalk is critical, regardless of location. Like roundabouts, the curvilinear nature of CTLs makes it substantially more difficult for a blind pedestrian to locate the appropriate crossing location and to maintain alignment through the crosswalk. Positive channelization also assists pedestrians without vision disabilities by encouraging them to cross at the appropriate crossing locations. Locaon: Center Opon 1: Marked Crosswalk Direcon: Parallel to Sidewalk Opon 2: Marked Crosswalk Locaon: Upstream End Direcon: Parallel to Sidewalk Opon 4: Marked Crosswalk Locaon: Downstream End Direcon: Perpendicular to Sidewalk Opon 3: Marked Crosswalk Locaon: Upstream End Direcon: Perpendicular to Sidewalk Direcon: Perpendicular to Sidewalk Locaon: Downstream End Opon 5: Marked Crosswalk Figure 5-7. CTL crosswalk location options (adapted from NCHRP Web-Only Document 208). Figure 5-7 shows five crosswalk location options at CTLs. The preferred option is (1) crosswalk at the center and at 90 degrees across the right-turn lane. Other options are less desirable for reasons discussed in the text, and include (2) crosswalk at the upstream end and parallel to the roadway entering the intersection, (3) crosswalk at the upstream end and at 90 degrees across the right-turn lane, (4) crosswalk at the exit and parallel to the roadway exiting the intersection, and (5) crosswalk at the exit and at 90 degrees across the right-turn lane.

56 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook • The channelization island itself needs to be designed following the same principles as the curbside crosswalk landing. Most islands have three crosswalk landings, and each landing needs to fol- low the accessibility principles. In addition, clear wayfinding guidance between these crossing points needs to be provided. From a driver’s perspective, there are also several conflicting challenges to balance: • Visibility of the crosswalk itself and of pedestrians in or about to enter the crosswalk. A crosswalk that is located toward the downstream end of the CTL can be less visible to approaching drivers than one located closer to the upstream entry point into the CTL. • Separation of decision points of interacting with pedestrians and downstream vehicles. At some point, drivers are expected to look left to screen the conflicting vehicle traffic for gaps to leave the CTL, which can make it more difficult to see a pedestrian waiting to cross from the right. This research found that separating these decision points can improve pedestrian safety and accessibility, by allowing drivers to focus on pedestrians before and independent of interacting with the downstream vehicular traffic stream. • Visibility of traffic control devices present at the crosswalk. This is particularly important for traffic control devices that change indication, such as pedestrian-activated flashing beacons, PHBs, and red-yellow-green traffic signals. • Driver speeds through the crosswalk area. Research suggests a strong relationship between the speed at which drivers are driving and their willingness to yield to a pedestrian. Research also shows a strong relationship between vehicle speed and the severity of any collisions that may occur. With regard to visibility, a guide for identifying the appropriate locations for a crosswalks is provided in Table 3-1, Stopping Sight Distance on Level Roadways, and Table 3-2, Stopping Sight Distance on Grades, of the Green Book. A portion of Table 3-1 is reproduced below as Table 5-2. These principles can be challenging to balance in retrofit situations where an optimal crosswalk location may not be achievable. There is also the potential concern of having a variety of crosswalk configurations used at the same intersection or within the same community, although there is no research at the time of this writing to confirm the safety impacts of this. Examples of good and poor crosswalk placement are shown in Figure 5-8 and Figure 5-9, respectively. 5.1.8 Recommended Crosswalk Placement Based on observations in this study, a centered crosswalk location is preferred at CTLs. While there are always exceptions and reasons to favor one of the other options described in Figure 5-7, Design Speed (mph) Brake Reaction Distance (ft) Braking Distance on Level (ft) Stopping Sight Distance (calculated) (ft) Stopping Sight Distance (design) (ft) 15 55.1 21.6 76.7 80 20 73.5 38.4 111.9 115 25 91.9 60.0 151.9 155 30 110.3 86.4 196.7 200 35 128.6 117.6 246.2 250 40 147.0 153.6 300.6 305 45 165.4 194.4 359.8 360 Note: Based on brake reaction distance of 2.5 s and deceleration rate of 11.2 ft/s2. Table 5-2. Stopping sight distance on level roadways (Table 3-1, AASHTO, 2011).

Design Principles for Pedestrian Access at Channelized Turn Lanes 57 placing the crosswalk at the center of the CTL (Option 1, see in Figure 5-10) is recommended in most cases for the following reasons: • The crossing is at a 90 degree angle. • Out-of-direction travel is equally distributed among pedestrian routes. • Ramps can be both perpendicular to the sidewalk and aligned with the crosswalk. • The crosswalk is visible to approaching drivers and a clear line of sight is provided between pedestrians and approaching drivers. • The crosswalk is likely to be upstream of a stop or yield line if one is present, and may provide sufficient space for one-vehicle length of storage between the crosswalk and the stop or yield line (similar to the entry to a roundabout). Figure 5-8. Example of a properly placed and aligned crosswalk at a CTL. Figure 5-8 shows an example of a properly placed and aligned crosswalk at a CTL. The crosswalk is located at the center of the CTL at a 90-degree angle across the turn lane, and leads to a sufficiently large and landscaped island. This installation however does not have adequate landscape separation on the curb. Figure 5-9. Example of a poorly aligned crosswalk at a CTL. Figure 5-9 shows an example of a poorly aligned crosswalk at a CTL. The slope of the ramp and detectable warn- ings do not point in the direction of the island, but rather into the street left of the island. The island size is further not sufficiently large, thus pedestrians in the research missed the island and walked into the intersection.

58 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook • The crosswalk location is likely to separate driver decision points of (1) interacting with the pedestrian and (2) interacting with downstream vehicle traffic. This allows the driver to focus on the interaction with pedestrians, before scanning for gaps in downstream traffic. • The channelization island provides sufficient raised area on either side of the crosswalk to minimize the chance of pedestrians missing the island and stepping into the travel lanes. An example of a well-placed and configured CTL crosswalk is shown in Figure 5-8. The instal- lation has the crosswalk in the center of the turn lane at a 90 degree angle across the turn lane. The installation is missing landscaping to delineate the crosswalk on the curb side, which should be retrofitted. On the island, the design features properly installed detectable warnings and crushed stone surface on areas not intended for walking, providing good channelization and wayfinding cues for pedestrians on the island. Figure 5-9 shows an example of a poorly located and configured CTL crosswalk. The curb ramp is at the upstream end of the CTL and slopes toward the left of the channelization island. A pedestrian lining up with the detectable warning and curb ramp slope is likely to miss the island and cross into the intersection. This was observed for several participants in experimental wayfinding trials as part of this research. 5.2 Traffic Control Device Applications A variety of traffic control devices can be used at the crosswalk to increase pedestrian visibility and encourage drivers to yield to pedestrians. They can range from typical warning signs and crosswalk markings to pedestrian-actuated flashing beacons. Higher yielding rates may result in more opportunities of crossing for pedestrians who are blind or who have low vision. However, as noted above, the pedestrian has to be able to detect that a vehicle has yielded, the driver has to wait long enough for the pedestrian to make that decision, and the pedestrian has to be willing to cross in front of a yielding vehicle. At multilane crossings, the second lane has the potential for multiple threat events and is a big concern for pedestrians who are unable to visually ascertain Figure 5-10. Recommended crosswalk location and configuration for CTLs. Figure 5-10 shows the preferred crosswalk location and configuration for CTLs, with the crosswalk located in the center of the CTL and oriented perpendicular to the approach. This configuration minimizes crossing distance, aids with alignment, provides good visibility of the crosswalk for motorists, and reduces wayfinding challenges once the island is reached.

Design Principles for Pedestrian Access at Channelized Turn Lanes 59 the status of the second lane before crossing. The proposed PROWAG requires a pedestrian- activated signal in those locations. 5.2.1 Vehicle Control Options for CTLs There are many vehicle control options for CTLs available that govern the interaction between vehicles in the CTL and the downstream merge point with the cross street. The primary treat- ments include yield control, free-flowing operation with a dedicated receiving lane, stop-control, signalization, and pedestrian-actuated beacons. Most state and local agencies do not have policies related to traffic control devices for CTLs (Potts et al., 2011), so a wide variety of control options may be in use in the same area. Variety creates challenges for blind pedestrians, because they may not be able to discern the configuration of a CTL at an intersection with which they are not familiar. In observations of driver behavior at CTLs, it has been repeatedly seen that the speed and compliance behavior of drivers varied depending on the phase of the signal at the adjacent inter- section. Driver speeds were noted to be higher and yielding compliance lower when the parallel through movement had a green indication than when it was red. Presumably, drivers knew that they had no downstream conflicts during the adjacent green phase, and as a result traveled faster and yielded less than when there was a chance for a downstream conflict. This is a characteristic likely to apply to most CTLs with yield control, no control, or signal control, and should be considered in any evaluation. The following sections present the advantages and disadvantages of different control devices for CTLs and are adapted from NCHRP Web-Only Document 208. 5.2.1.1 Yield Control Yield control may be the most common form of traffic control at CTLs that do not have an acceleration lane. Advantages • Enables vehicles to proceed without stopping in the absence of conflicting vehicles and pedestrians and • Well-suited for the flat angle entry design presented in the Green Book. Disadvantages • Potential for high speeds by vehicles, • Potential for queues to stack across the crosswalk (assuming the crosswalk is placed in the middle of the CTL), and • The yield control and lack of a pedestrian signal can be especially challenging for blind pedestrians. 5.2.1.2 No Control For CTLs with acceleration lanes, oftentimes there may be no traffic control device. Instead, traffic through the CTL flows freely and merges with downstream traffic. Advantages • Enables vehicles to proceed without stopping and • Well-suited for the flat angle entry design presented in the Green Book. Disadvantages • Potential for high speeds by vehicles, • Requires right-of-way for the receiving lane on the downstream roadway, and

60 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook • Lack of a control device can be challenging for pedestrians, especially for those who are blind. 5.2.1.3 Stop-Control Stop-control at CTLs is uncommon, unless the stop sign is required because of considerations for vehicular sight distance or other safety considerations. The configuration is similar to a yield- controlled CTL, but with a stop sign and a stop bar at the merge point. Advantages • Stop requirement for all vehicles is beneficial to pedestrians and • Stop requirement for all vehicles can enhance vehicle safety if sight distances are compromised by the CTL design. Disadvantages • Imposes delay on all vehicles even without pedestrians present, which may lead to drivers ignoring the traffic control device over time; • Uses traffic signals at the same intersection, which may be confusing to or unexpected by some pedestrians; and • Lack of a signal may be challenging for blind pedestrians. 5.2.1.4 Signal Control Signal control is common at two-lane CTLs to allow both lanes to safely merge into the down- stream traffic stream. However, even single-lane CTLs may be signalized for safety consider- ations or to provide a clearly defined crossing interval for pedestrians. Advantages • Signalized crosswalks are beneficial to pedestrians (APS devices are needed to make the signals accessible), • Enables pedestrians who are blind to accurately determine the onset of an intended crossing time and eliminates multiple lane threat, and • Enables designs with two or more right-turn lanes. Disadvantages • Imposes delay on vehicles, especially if right turn on red is prohibited; • If the movement operates with overlap phasing, it may be necessary to prohibit U-turns from the associated left-turn lane to avoid conflicts on the exit leg; and • Signal equipment increases the cost of CTLs. 5.2.2 Pavement Markings For pedestrians with low vision, marked crosswalks can provide an essential cue to the cross- walk location and assist with maintaining travel within the crosswalk. Pedestrians with low vision have stated a preference for ladder-type crosswalk markings. Ladder markings have both transverse and longitudinal lines. The transverse lines make it easier for a person with low vision to follow a line across the crosswalk and the longitudinal lines enhance crosswalk visibility to drivers. Crosswalks that are brick colored may not be distinguishable from the asphalt street color under low illumination as well as for individuals who are color blind, and they are not as visible to drivers. An example of ladder-style crosswalk markings was shown in Figure 4-17. MUTCD, Section 3B.16, provides language on the placement of stop bars associated with crosswalks. MUTCD, Section 4D.14, indicates that signal faces shall not be less than 40 ft from the stop bar “except where the width of the intersecting roadway or other conditions makes it

Design Principles for Pedestrian Access at Channelized Turn Lanes 61 physically impractical.” The crosswalk design should account for the location of the stop bar and where vehicles will queue when determining crosswalk location. 5.2.3 Signs A number of signs are appropriate at CTLs as discussed below. 5.2.3.1 STOP (R1-1) and YIELD (R1-2) Signs If the CTL is sign-controlled, then either a stop or an yield sign must be used at the exit of the CTL. If sight lines and crosswalk placements allow, it may be advantageous to place the stop or the yield sign in advance of the crosswalk. 5.2.3.2 In-Street Pedestrian Crossing Signs (R1-6 and R1-6a) An in-street sign reminding drivers that it is a state law to yield to or stop for pedestrians within the crosswalk (Figure 5-11) may increase yielding behavior. Research at non-roundabout loca- tions has found these signs are effective in increasing the yielding behavior of drivers (Fitzpatrick et al., 2006). 5.2.3.3 Yield Here to Pedestrians (R1-5 and R1-5a) Signs The yield here to pedestrians sign, Figure 5-12, is intended to be used in conjunction with an advance yield line to encourage drivers to stop further from the crosswalk. However, vehicles stop- ping further from the crosswalk may make it harder for blind pedestrians to detect the vehicle that has yielded and may lead to unexpected conflicts. However, having a sign clearly indicating to drivers where they are intended to yield presumably enhances the predictability of where to listen for yields. R1-6 R1-6a Figure 5-11. In-road pedestrian signs. Figure 5-11 shows two examples of in-road signs reminding drivers of the state law to either yield or stop for pedestrians within a crosswalk. The signs are listed in MUTCD as numbers R1-6 and R1-6a, respectively.

62 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook 5.2.4 Rectangular Rapid-Flashing Beacons RRFBs are typically activated by a pedestrian pushbutton. The flashing display is associated with identifying the presence of a pedestrian by drivers and may result in more yielding. In the research, blind pedestrians noted that they liked knowing they had activated a beacon that was highly visible to drivers, and it gave them greater confidence that a vehicle might yield. Pedestri- ans who are blind still need to be able to recognize that vehicles have yielded, drivers have to wait long enough for the detection, and pedestrians have to be willing to cross in front of a stopped vehicle. The multiple threat issue is also not resolved. For usability by a pedestrian who is blind, an RRFB must be equipped with an audible infor- mation device, providing a pushbutton locator tone to help the pedestrian find the push button, and an audible message telling the pedestrian that “yellow lights are flashing.” Figure 5-13 shows an example of an RRFB at a roundabout entry, but the device could similarly be used at a CTL. 5.2.5 Pedestrian Signals and Pedestrian Hybrid Beacons For pedestrians who are blind or who have low vision, a pedestrian-activated signal that pro- vides a red indication to vehicles and a walk indication to the pedestrian is most definitive and more comfortable. To provide access for pedestrians who are blind, the pedestrian signals must include APS to provide information about the signal phases. Research at mid-block locations also showed that devices with a red indication resulted in the highest driver yield compliance of all treatments, typically well above 90% (Fitzpatrick et al., 2006). Pedestrian signal face locations and APS are discussed in MUTCD, Chapter 4E. Specific atten- tion should be made to the location of APS units next to the crosswalk and separated from one another, especially within the splitter island. Refer to MUTCD, Sections 4E.08 to 4E.13, for fur- ther guidance on this topic. If the CTL is itself signalized for vehicular traffic, then a standard pedestrian signal with a red-yellow-green indication for drivers and a walk/flashing don’t walk/don’t walk sequence for R1-5 R1-5a Figure 5-12. Yield here to pedestrian signs. Figure 5-12 shows two examples of roadside signs indicating to drivers where to yield to pedestrians. The signs are listed in MUTCD as numbers R1-5 and R1-5a, respectively.

Design Principles for Pedestrian Access at Channelized Turn Lanes 63 pedestrians (along with audible information) can be used. If the CTL is yield-controlled, a PHB may be a good option. The PHB is a device that is geared at enhancing the operational efficiency compared to a standard signal, but still provides similar safety benefits due to a steady red indica- tion. The PHB provides much of the same benefit as a standard pedestrian signal, but does not show a green indication that could be confused with the yield sign. 5.2.6 Treatments to Facilitate Wayfinding The same philosophy and many of the same treatments used at roundabouts to facilitate way- finding also apply to CTLs. This section presents examples specific to CTLs. Chapters 4.1 and 4.2 refer to the treatments discussed in the context of roundabouts. 5.2.6.1 Detectable Warning Surface (truncated domes) to Indicate the Edge of the Street An example of a detectable warning surface at a CTL is shown in Figure 5-14. The bollards to the left and right of this crosswalk limit vehicular travel on the sidewalk, but do not provide wayfinding guidance for blind pedestrians in the task of locating the crosswalk. 5.2.6.2 Raised Crosswalk Slopes to Provide Cue to Maintain Travel within the Crosswalk A raised crosswalk, shown in Figure 5-15, can assist pedestrians who are blind in staying within the crosswalk for the entire crossing. Pedestrians may be able to detect the sloping sides of a raised crosswalk and use the slopes as boundaries. While a detectable warning sur- face covering the width of the crosswalk is present at this CTL, blind pedestrians had dif- ficulty locating the crosswalk because landscaping was not provided on either side of the crosswalk. More than one pedestrian walked into the street without realizing it because the curb was not detectable (less than an inch of vertical separation) near the crosswalk because of the raised crosswalk. Figure 5-13. RRFB at a two-lane roundabout. Figure 5-13 shows an RRFB at a two-lane roundabout. The device could also be applied to CTLs to increase driver awareness of a pedestrian wanting to cross.

64 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook It is critical that detectable warning surfaces be used to define the boundary between the pedestrian and vehicular ways at raised crosswalks, which create a blended transition area, or raised crosswalks are likely to result in blind pedestrians being within the vehicular way without being aware of it or taking appropriate steps to determine a safe crossing time. Detectable warn- ings are required at curb ramps by the Department of Transportation’s ADA Standards and by PROWAG-NPRM R208.1, “Curb ramps and blended transitions at pedestrian street crossings.” A raised crosswalk results in a blended transition between the pedestrian and vehicular way. Figure 5-14. Detectable warning surface installed at a CTL crossing. Figure 5-14 shows an example of a detectable warning surface installed at the base of the curb ramp at the crossing of a CTL toward the island. The detectable warning surface extends the full width of the ramp that is level with the street. Large bollards approximately 10 ft to 12 ft apart are visible along the curb line near the crosswalk. Figure 5-15. Raised crosswalk at a CTL. At the CTL in Figure 5-15, the crosswalk across the lane is level with the sidewalk and a detectable warning surface is installed across the area where the sidewalk is level with the street. There are chevrons on the upslope to alert drivers. Detectable warnings are present at the boundary between the pedestrian and vehicle way, but no landscap- ing is provided on either side of the crosswalk.

Design Principles for Pedestrian Access at Channelized Turn Lanes 65 Some municipalities are adopting standardized treatments of their CTLs, including the City of Boulder, Colorado, which uses raised crosswalks at almost all of their CTLs to reduce vehicle speeds and enhance pedestrian safety. 5.2.6.3 Pushbutton Locator Tones may Provide a Cue for Locating the Crosswalk and for Maintaining Correct Heading while Crossing The pushbutton locator tones that are a required feature in APS indicate the location of the pedestrian pushbutton. In addition, pushbutton locator tones may be used on other push- buttons, such as those for RRFBs. Pushbuttons, shown in Figure 5-16, should be located as close as possible to the crosswalk (see MUTCD, Section 4E.8); therefore, pedestrians who are blind can be guided to the approximate location of the crosswalk by pushbutton locator tones. In addition, most crossings at CTLs are one-lane wide, and it is likely that blind pedestrians will be able to hear the pushbutton locator tone from the device at the far end of the crosswalk as they cross, helping them to stay within the width of the crosswalk. Pushbuttons and APS or audible information devices should be located downstream of the crosswalk, so they are not in-between the pedestrian and the approaching traffic they are trying to listen for, and so they do not block the view of drivers that need to see the pedestrian waiting. 5.2.7 Other Traffic Control Devices and Pedestrian Treatments The control options described in Chapter 5.2.1 are primarily intended for motor vehicle control. At some CTLs, control devices and treatments to assist and increase driver awareness of pedestrian crossings have been added. Control devices include flashing beacons, PHBs, and RRFBs, which were discussed earlier. Figure 5-16. Pushbuttons with pushbutton locator tones assist with locating the crosswalk and maintaining correct heading while crossing. In Figure 5-16 pushbuttons with pushbutton locator tones are visible at the side of the curb ramp at this entry lane roundabout crossing. In addition, there is a pushbutton with a pushbutton locator tone on the splitter island. Detectable warnings are visible at the base of each curb ramp.

66 Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook Additionally, the following treatments have been used to enhance accessibility at CTL crosswalks: • Sound strips (road surface treatments similar to rumble strips), specifically for blind pedes- trians, and • Raised crosswalks or other vertical deflection to slow vehicles. However, some municipalities are adopting standardized treatments of their CTLs, including the City of Boulder, Colorado, which uses raised crosswalks at almost all of their CTLs to reduce vehicle speeds and enhance pedestrian safety. Sound strips across deceleration lanes have been tested at CTLs to provide additional audi- tory information to pedestrians who are blind (Figure 5-17). The sound strips may enable pedestrians who are blind to auditorily distinguish turning traffic from through traffic when a deceleration lane is present, as well as allow some inferences about vehicle speed (shorter intervals between sounds indicate faster speeds). Sound strips may further assist in the identi- fication of yield events, as a slowing vehicle generates different sound patterns from a vehicle traveling at constant speed. In NCHRP Project 03-78A and 03-78B, different rumble strip materials were used for sound strips at CTLs. In order to be effective, the sound treatment must be placed far enough to give audible cues in time for the pedestrian to make a deci- sion. Strips were installed across the CTL deceleration lane at 30-ft intervals beginning 150 ft before the crosswalk (distance determined by the speed of approaching vehicles). However, for both materials, sound was not generated if vehicles were traveling very slowly over the strips. This inconsistency in cues led to confusion for blind participants in the research. While this might be a feasible solution, more research is needed to determine appropri- ate materials and installation to provide consistent sound cues in the noisy intersection environment. Treatments that provide vertical deflection, such as raised crosswalks and speed humps, may improve the likelihood of drivers yielding to pedestrians. Design considerations for raised cross- walks specific to CTLs have not been developed. It is believed to be possible to combine either Figure 5-17. Sound strips installed at a CTL. Figure 5-17 shows sound strips installed across the deceleration lane approaching an intersection. Three strips are visible as low foot-wide bars across the deceleration lane in this photograph. The crosswalk is just out of view as the lane curves.

Design Principles for Pedestrian Access at Channelized Turn Lanes 67 the PHB or the RRFB with a raised crosswalk. Care is needed in ensuring an appropriate set of signs and pavement markings to accompany the combined treatments. Raised crosswalks or speed humps force drivers to slow down (Figure 5-18). Lower speeds have also been linked to increased yielding behavior (Geruschat and Hassan, 2005; Scroeder et al., 2015). Like roundabouts, the curvilinear nature of CTLs makes it substantially more difficult for a blind pedestrian to locate the appropriate crossing location and to maintain the correct heading through the crosswalk. Figure 5-18. Raised crosswalk at a CTL. At this large 4-way signalized intersection in Boulder, Colorado (Figure 5-18), a CTL has a raised crosswalk. It is marked with chevrons that are visible on the up-slope. There is no landscaping or barrier between the wide sidewalk and the curb line that can help pedestrians with visual impairments find the crosswalk. However, there are large bollards at each side of the crosswalk that blind pedestrians who are familiar with this crossing might be able to use to identify the location of the crosswalk.