Effects of Weather on Highway Traffic Capacity in China: Characteristics and Causes of Roadblocks Due to Fog Events

• Published in: Pure and applied geophysics 2020-10, Vol.177 (10), p.5027-5040
• Main Authors: Jiang, Ying, Zhang, Nan, Li, Aixun, Wu, Hao, Li, Runchun, Yang, Jing
• Format: Article
• Language: English
• Subjects: Earth and Environmental Science; Earth Sciences; Geophysics/Geodesy
• ISSN: 0033-4553; 1420-9136
• DOI: 10.1007/s00024-020-02535-8

Fog-induced highway roadblocks (access restrictions and traffic congestion) include not only the influence of fog conditions on traffic capacities but also human factors and traffic conditions that affect highway traffic. They directly reflect the combined effects of weather conditions, traffic conditions, and human factors on the flow of traffic. This work systematically studies the characteristics and causes of fog-blocked events in China and finds that the annual total mileage of highways in China that are blocked by fog events is roughly 178% of the entire national highway mileage. The distribution of fog-blocked events is very uneven in China, with 88.5% of annual totals occurring in East China, Central China, and North China. The high-occurrence period for fog roadblocks is around sunrise, whereas its low-occurrence period is from noon to nightfall. Roadblocks occur more frequently, with earlier peak time, in South China than in North China. Winter represents the high-occurrence period for fog-blocked events, followed by spring, autumn, and summer. Fog distribution characteristics, along with seasonal and diurnal variations, are generally consistent with those of fog-blocked events. All the above characteristics indicate that fog conditions are the main reason for fog-induced highway roadblocks. In addition, roadblocks are also affected by traffic flow, road network density, culverts and bridges, curved roads, slopes, and other conditions.