
Countermeasure | Tier 1: Remove Severe Conflicts | Tier 2: Reduce Vehicle Speeds | Tier 3: Manage Conflicts in Time | Tier 4: Increase Attentiveness and Awareness |
|---|---|---|---|---|
Road reallocation | √ | √ | ||
Speed feedback signs | √ | |||
Automatic speed enforcement | √ | |||
Lower speed limits | √ | √ | ||
Lighting | √ | |||
Marked crosswalks | √ | |||
Traffic signals | √ | |||
Pedestrian hybrid beacons | √ | |||
Rectangular rapid flashing beacons | √ | |||
Daylighting/curb extensions | √ | |||
Crossing islands | √ | √ | ||
Sidewalks/walkways/shared use paths | √ |
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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 |
FAST | Fixing Americaʼs 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 |
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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