Guidelines for Grading Traffic Conditions on Highways in Adverse Weather

This document establishes a systematic framework for classifying traffic conditions on expressways during adverse weather events. It defines specific meteorological thresholds and corresponding visibility, road surface, and wind speed criteria to categorize different levels of operational risk. The content outlines precise indicators for dividing scenarios into distinct grades, ranging from normal operations to severe restrictions. By providing clear definitions for these conditions, the guidance enables traffic management authorities and road operators to implement standardized response protocols tailored to each severity level. The document specifies the necessary measurements and observation methods required to determine the current status. It serves as a technical reference for deploying appropriate safety measures, including speed control, lane closures, and traffic diversion strategies. The approach ensures consistency in decision-making processes across different regions. All recommendations focus on enhancing safety and maintaining orderly traffic flow while minimizing disruption. This guidance supports the development of local emergency plans and operational procedures without altering the underlying safety regulations or administrative responsibilities.