Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities: A Guidebook (2017) / Chapter Skim
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Pages 48-67
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From page 48... ...
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.
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From page 49... ...
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 wayfinding 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.
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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 minimum of 50 ft2 in urban areas and 75 ft2 in rural areas, to assure that the island is readily visible to approaching drivers.
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Design Principles for Pedestrian Access at Channelized Turn Lanes 51 (a)
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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.
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Design Principles for Pedestrian Access at Channelized Turn Lanes 53 the downstream yield point for vehicles. This last feature separates driver decisions of interacting with pedestrians (yielding)
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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, softwaregenerated 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.
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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)
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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 follow the accessibility principles.
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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.
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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)
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Design Principles for Pedestrian Access at Channelized Turn Lanes 59 the status of the second lane before crossing. The proposed PROWAG requires a pedestrianactivated signal in those locations.
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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.
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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.
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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.
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Design Principles for Pedestrian Access at Channelized Turn Lanes 63 pedestrians (along with audible information) can be used.
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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 warnings 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.
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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.
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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 pedestrians, and • Raised crosswalks or other vertical deflection to slow vehicles.
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From page 67... ...
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.
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