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181  AADT annual average daily traffic volume for the segment and year of interest AADTmajor annual average daily traffic volume for the major road and year of interest (both directions of travel combined) AADTminor annual average daily traffic volume for the minor road and year of interest (both directions of travel combined) a, b, and c regression coefficients estimated for each specific crash severity and site type ci a vector of coefficients estimated for the other independent variables included in the model CMFparking CMF for on-street parking CMFT CMF for target crashes CMFTFI CMF for target fatal and injury crashes CMFyx CMFs specific to site type x and specific geometric design and traffic control features y Cx calibration factor to adjust SPF for local conditions for site type x ISDnew new or proposed available intersection sight distance ISDold existing or base available intersection sight distance k dispersion parameter associated with the SPF L segment length Lpk sum of curb length with on-street parking for both sides of the road combined LowAADTmaj 1 if major road AADT ⤠5,000; otherwise 0 LowMidAADTmaj 1 if major road AADT ⤠15,000; otherwise 0 MidAADTmaj 1 if 5,000 < major road AADT ⤠15,000; otherwise 0 Nbikex predicted average number of vehicle-bicycle collisions per year for site type x Nbimv predicted average crash frequency of multivehicle intersection crashes for base conditions Nbisv predicted average crash frequency of single-vehicle intersection crashes for base conditions Nbrmv predicted average crash frequency of multivehicle (non-driveway) segment crashes for base conditions Nbrsv predicted average crash frequency of single-vehicle segment crashes for base conditions Ndrwy predicted average crash frequency of multivehicle driveway-related crashes nj total number of driveways within the segment (both sides of road) of driveway type j Nj average number of driveway-related crashes per driveway per year for driveway type j Variables
182 Application of Crash Modification Factors for Access Management Npedx predicted average number of vehicle-pedestrian collisions per year for site type x Npredicted predicted average crash frequency for a specific year on site type x Npedx predicted average number of vehicle-pedestrian collisions per year for site type x Nspf int predicted average crash frequency of an individual intersection for base conditions (excluding vehicle-pedestrian and vehicle-bicycle crashes) Nspf rs predicted average crash frequency of an individual segment for base conditions (excluding vehicle-pedestrian and vehicle-bicycle crashes) Nspf x predicted average crash frequency determined for base conditions of the SPF developed for site type x ppk proportion of curb length with on-street parking PSL posted speed limit t coefficient for traffic volume adjustment estimated for each specific site type X signal spacing for the base condition xi a vector of other independent variables included in the model Y signal spacing for the condition of interest wmv weight factor for multivehicle crashes
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 ACIâNA Airports Council InternationalâNorth 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 FAST Fixing Americaâs Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration GHSA Governors Highway Safety Association 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) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S. DOT United States Department of Transportation
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