GB/T 46251-2025Specification for identification of high-impact sections of road dense fog (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents. This document was proposed by the China Meteorological Administration. This document is under the jurisdiction of the National Meteorological Disaster Prevention and Mitigation Standardization Technical Committee (SAC/TC345). This document was drafted by: Anhui Provincial Public Meteorological Service Center, Traffic Management Bureau of the Ministry of Public Security, and Road Network Monitoring and Emergency Response Department of the Ministry of Transport. The center, the Road Traffic Safety Research Center of the Ministry of Public Security, the Traffic Management Corps of the Anhui Provincial Public Security Department, and the Nanjing Meteorological Science and Technology Innovation Research Institute. The main drafters of this document are. Jiang Chun, Zhou Jianping, Zhang Di, Yu Liyun, Li Yingwei, Yin Xihui, Suo Chen, Wu Xiaofeng, Ding Guoxiang, and Yao Yeqing. Miao Kaichao, Ji Lei, Ge Jinjun, Tao Yin, Zu Fan, Zhu Chengying, Liu Duanyang. Inspection and Investigation Standards for Road Sections Highly Affected by Dense Fog

1 Scope

GB/T 46251-2025 is the Chinese national standard covering finding the stretches of road where fog forms and kills - the meteorological and terrain conditions that produce it, the accident history, the survey and the observation period, and the classification that decides where warning systems go. Fog-related pile-ups on expressways are among China's worst road accidents. First edition, under the China Meteorological Administration. In force from 1 May 2026. Issued on 5 October 2025, it has been in force since 1 May 2026.

This document specifies the process for investigating road sections heavily affected by dense fog, as well as the requirements for investigation data, direct judgment, comprehensive judgment, and result summarization. The corresponding verification method was provided. This document applies to the investigation of sections of highways heavily affected by dense fog; ordinary roads can refer to it for reference.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included. For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies. This document. GA/T 543.10-2016 Public Security Data Elements (10) JTGB

01 Technical Standards for Highway Engineering

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 Visibility During the day, a person with normal vision (contrast threshold of 0.05) can see or identify objects against the background sky under the given weather conditions. The maximum horizontal distance at which a black, moderately sized object can be seen and identified at night; the maximum horizontal distance at which a medium-intensity luminous object can be seen and identified.

Note. The unit is meters (m). [Source: GB/T 21984-2017, 2.19, with modifications]

3.2 Number of dense fog days The number of days with visibility (3.1) less than.200m, with

20.00 Beijing time as the day boundary.

3.3 Traffic volume The number of vehicles or pedestrians passing through a certain section of a road per unit of time. [Source: GB/T 31418-2015, 2.2.3]

3.4 A section of road where traffic safety and traffic efficiency are significantly affected by dense fog.

4.Investigation Process The investigation of road sections highly affected by dense fog should begin with data collection, followed by direct or comprehensive assessment, and finally, the investigation results should be summarized. Among these, comprehensive assessment... The determination of high-impact road sections due to dense fog should be based on the results of dense fog risk assessment and disaster prevention and mitigation capacity assessment. Figure 1 specifies the high-impact road sections due to dense fog.