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From page 137... ... NCHRP 3-78b: Final Project Report April 2016 137 11 APPENDIX D: CROSSING SIGHT DISTANCE DETAILS 11.1 Introduction This report presents the results of research to develop guidance for designing crosswalks at modern roundabout and channelized turn lanes (CLTs) to assist pedestrians with vision disabilities. Read the entire page →
From page 138... ... NCHRP 3-78b: Final Project Report April 2016 138 roundabout segment methodology in Chapter 30 of the 2010 Highway Capacity Manual (TRB, 2010) Read the entire page →
From page 139... ... NCHRP 3-78b: Final Project Report April 2016 139 newly developed study protocol -- enhanced based on the lessons learned in NCHRP 3-78A. Through studies conducted in this research, and supported by earlier accessibility work, this team sought to identify what aspects of geometry contribute to enhanced accessibility, and to document these findings. Read the entire page →
From page 140... ... NCHRP 3-78b: Final Project Report April 2016 140 d3,e = (1.467) (V3,entering) Read the entire page →
From page 141... ... NCHRP 3-78b: Final Project Report April 2016 141 tn,c = (Ln / Sp) + ts Sight Distance (Avg Speed) Read the entire page →
From page 142... ... NCHRP 3-78b: Final Project Report April 2016 142 Entry d C1 d C2 d C3 Entry d C4 d C5 Reaction Time (sec) 2 0 0 Reaction Time (sec) Read the entire page →
From page 143... ... NCHRP 3-78b: Final Project Report April 2016 143 the fastest path of a right-turning vehicle. These radii paths are not the same as the curb radii path and R1 through R5 measured using the vehicle centerline in its path through the roundabout. Read the entire page →
From page 144... ... NCHRP 3-78b: Final Project Report April 2016 144 ICD = inscribed circle diameter (ft) , Nc = number of circulating lane(s) Read the entire page →
From page 145... ... NCHRP 3-78b: Final Project Report April 2016 145 V3 = exit speed, mph; V3pbase = V3 speed predicted based on path radius, mph; V2 = circulatory speed for through vehicles predicted based on path radius, mph; a23 = acceleration between the midpoint of V2 path and the point of interest along V3 path = 6.9 ft/s2; and d23 = distance along the vehicle path between midpoint of V2 path and point of interest along V3 path, ft. After estimating the speed for all the movements along each path and in order to obtain the through and left-turn movement speed, the average of total speed for entry and circulating vehicle (V2+V3+V4/3) Read the entire page →
From page 146... ... NCHRP 3-78b: Final Project Report April 2016 146 11.5 Summary Summarizing the discussion above, the team proposed a total of 20 sight distance pedestrian approaches to be analyzed for roundabouts and channelized turn lanes, with some of them having treatment installations such as raised crosswalks to reduce the vehicle speed in five different states across the United States. Roundabouts and CTLs present similar challenges to pedestrians who are blind, since they both have yield controlled approaches to the intersection. Read the entire page →
From page 147... ... NCHRP 3-78b: Final Project Report April 2016 147 11.6 Sight Distance Calculation Details Maple Rd and Farmington Rd., Novi, MI Approach Leg: East Exit ICD (ft) R1 R2 R3 R4 R5 d12 d23 251 118 104 122 104 166 180 165 Radius decel accel Field RCW Min V1 21 33 21 V2 (Sc) Read the entire page →
From page 148... ... NCHRP 3-78b: Final Project Report April 2016 148 Cherrywood and Greenbelt Metro, Greenbelt MD Approach Leg: West Exit ICD (ft) R1 R2 R3 R4 R5 d12 d23 96 67 40 97 40 86 105 155 V,Radius decel accel Field RCW Min V1 17 25 17 V2 (Sc) Read the entire page →
From page 149... ... NCHRP 3-78b: Final Project Report April 2016 149 11.7 Sight Distance Example Application This appendix provides all the final calculations from the "Approach 3" method, and aerial views of all the study sites where calculated sight distance paths were calculated. ROUNDABOUT CROSSING SIGHT DISTANCE RESULTS Maple Rd and Farmington Rd., Novi, MI East Exit (L & T) Read the entire page →
From page 150... ... NCHRP 3-78b: Final Project Report April 2016 150 Cherrywood and Greenbelt Metro, Greenbelt MD Westt Exit (L & T) Read the entire page →
From page 151... ... NCHRP 3-78b: Final Project Report April 2016 151 Nixon Rd and Huron Rd., Ann Arbor, MI East Exit (L & T) Read the entire page →
From page 152... ... NCHRP 3-78b: Final Project Report April 2016 152 Old Apex Rd. Read the entire page →
From page 153... ... NCHRP 3-78b: Final Project Report April 2016 153 Sabino Canyon & Tanque Verde Rd., Tuscan, AZ Approach NE Radius of Curve (ft) 176 Reaction Time (sec) Read the entire page →
From page 154... ... NCHRP 3-78b: Final Project Report April 2016 154 E River Rd. Read the entire page →
From page 155... ... NCHRP 3-78b: Final Project Report April 2016 155 Wilmot Rd. and Speedway Blvd. Read the entire page →
From page 156... ... NCHRP 3-78b: Final Project Report April 2016 156 28th St. and Canyon Blvd., Boulder CO Approach SW Radius of Curve (ft) Read the entire page →
From page 157... ... NCHRP 3-78b: Final Project Report April 2016 157 Foothills Pkwy. and Baseline Rd., Boulder CO Approach SW NE Radius of Curve (ft) Read the entire page →
From page 158... ... NCHRP 3-78b: Final Project Report April 2016 158 Kildaire Farm Rd. and Tryon Rd., Cary NC Approach SW Radius of Curve (ft) Read the entire page →

From page 137...

... NCHRP 3-78b: Final Project Report April 2016 137 11 APPENDIX D: CROSSING SIGHT DISTANCE DETAILS 11.1 Introduction This report presents the results of research to develop guidance for designing crosswalks at modern roundabout and channelized turn lanes (CLTs) to assist pedestrians with vision disabilities.