Superelevation Criteria for Sharp Horizontal Curves on Steep Grades (2014) / Chapter Skim
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Pages 173-183
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From page 173... ...
C-1 A P P E N D I X C This appendix provides potential changes recommended for consideration in the next editions of the Green Book and Manual on Uniform Traffic Control Devices (MUTCD) , based on findings and conclusions of this research.
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C-2 are designed so vehicles can avoid skidding with a margin of safety, the f values used in design should be substantially less than the coefficient of friction at impending skid. The side friction factor at impending skid depends on a number of other factors, among which the most important are the speed of the vehicle, the type and condition of the roadway surface, and the type and condition of the vehicle tires.
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C-3 side friction factor should not exceed 0.10 for design speeds of 110 km/h [70 mph] and higher.
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C-4 Speed (km/h) 40 48 56 64 72 80 89 97 105 113 121 129 137 Speed (mph)
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C-5 The maximum allowable side friction factors for low-speed streets and highways are shown in Figure 3-5. For travel on sharper curves, superelevation is needed.
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C-6 Passenger vehicle re measurements of skidding wet-re fricon in lateral Truck re measurements of skidding wet-re fricon in lateral (cornering) Speed (km/h)
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C-7 Text beginning on pg. 3-33 of 2011 Green Book (2)
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C-8 attained at the PC, the runoff lies entirely on the approach tangent, where theoretically no superelevation is needed. At the other extreme, placement of the runoff entirely on the circular curve results in the initial portion of the curve having less than the desired amount of superelevation.
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From page 181... ...
C-9 on roadways with downgrades of less than 4 percent; the specific value in this range should be dependent on design speed and rotated width. Experience obtained from existing practice indicates that deviation from the values in Table 3-18 by 10 percent should not lead to measurable operational problems.
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C-10 On upgrades of 4 percent or more, the maximum superelevation rate should be limited to 9 percent for minimum-radius curves with design speeds of 90 km/h [55 mph] and higher, to minimize the potential for wheel-lift events on tractor semi-trailer trucks.
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From page 183... ...
Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005)
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