The Impact Of Adverse Weather On The Road Driving In Beijing-Tianjin-Hebei And Surrounding Areas

With the rapid development of Chinese roads,traffic accidents continue to grow.The accidents are directly or indirectly affected by meteorological conditions at that time.Therefore,studying the impact of adverse weather conditions on road traffic safety from the meteorological conditions of road traffic accidents is of great significance for reducing the incidence of traffic accidents.In this paper,based on the data of traffic accidents under different road conditions,CMORPH-fusioned hourly precipitation of 0.1° grid dataset and the surface meteorological observation data,the impact of adverse weather on road driving in Beijing-Tianjin-Hebei and surrounding areas was analyzed systematically by statistics methods.The main results were as follows:(1)Through the analysis of the number of accidents every hundred kilometer,the average number of casualties per accident and the average direct economic loss per accident,it was found that the wet,icy and snowy,and water surface were the three main types of road conditions that affected road safety.From the comprehensive index of traffic accident consequences,the accident loss of the 108 national highway was the most serious in the 9 national highways,and the accident loss of icy and snowy surface was the most serious under various road conditions.The top three in the accident-prone road sections were the Luliang section of the 209 national highway and the 307 national highway and the Weifang section of the 309 national highway.The number of traffic accidents in 2011-2015 reached the least in 2014 and the most in 2015 under five road conditions namely wet,icy and snowy,water,flooded and muddy surface;the period of high incidence of accidents was from July to September under wet,water and flooded surface,the peak of accidents occurred in December under the icy or snowy surface,and the peak of accidents occurred in Novemberunder muddy surface;most accidents occurred during the day(07:00-19:00).(2)Compared with the east-west road,the north-south road had more obvious difference in monthly spatial distribution characteristics of precipitation,and the spatial boundary was more clear.The average hourly peak precipitation of the east-west road was more in the eastern section than in the western section,and the peak precipitation was more in the southern section than in the northern section during the snow season and non-snow season.In the eastern,western,southern and northern road points,the change trend of rainfall was similar on a monthly basis,and the changes of snowfall were relatively different.In the non-snow season,the diurnal variation peak of the eastern and western road points appeared in the afternoon,in the snow season,the precipitation peak of the western road point appeared at noon,and the peak of the eastern road point was not obvious.In the non-snow season,the precipitation of the northern road point was more in the afternoon and early morning and less at noon,the southern road point had a distinct single peak in the afternoon.In the snow season,the precipitation of the southern and northern road point was significantly different bounded by noon.(3)The fog(<1 km)frequency in the east-west road and the north-south road was less than 10 times.The frequency of light fog(1-10 km)in the east-west road had a small peak in the east section in most months,and light fog in the north-south road increased from north to south.The frequency of fog and light fog change similarly in space at 08:00,14:00 and 20:00.The monthly distribution of fog was characterized by high both ends and low in the middle,mainly occurring in winter.The fog and light fog appeared most at 08:00,followed by 20:00 and 14:00.The fog appeared more in the autumn and winter,and the light fog appeared more in the summer and autumn.(4)From the frequency and extent of the impact of weather phenomena on low visibility,fog had the greatest impact on low visibility of road,followed by rain and snow.Low visibility fog was concentrated along the southern road in Hebei Province.The spatial distribution of low visibility rain and snow was relatively scattered.Under the low visibility of each level,the relative humidity was between 90-100%,and the wind speed was below 2m/s.This showed that high relative humidity and low wind speed were favorable for the formation of low visibility under certain circumstances.The spatial distribution of annual average frequency of low visibility(<1km)had obvious characteristics of high in the south,low in the north and high in the east and low in the west,mainly concentrated in the eastern Beijing,Tianjin,southern Hebei,northern Shanxi,most parts of Shandong and Henan.Highways in southern Hebei and westernmost of Shandong were in high risk areas of low visibility.(5)Taking the Weifang section of the 309 national highway in Shandong as an example,the traffic safety analysis of the unfavorable weather was carried out.The hourly rainfall of this section mainly consisted of light rain and moderate rain,and the number of occurrences accounted for 98.12% of the total number of rainfalls.The daily snowfall was mainly light snow and moderate snow,and the number of occurrences accounted for 89.28% of the total snowfall days.The fog was mainly light fog,and the number of occurrences accounted for 94.61% of the total number of fogs.For different levels of weather,the driving safety speed of the long downhill section was given according to the adhesion coefficient and visibility.It was recommended to limit the vehicle speed of 110 km/h,90 km/h,70 km/h,and 50 km/h in light rain,moderate rain,heavy rain and torrential rain.It was recommended to consult the limit speed of rainy day when there was no snow or ice on the road under different grades of snowfall.When the visibility were 200 m,100 m and 50 m respectively,the limit speed were 70 km/h,50 km/h and 30 km/h for snowy road,the limit speeds were 40 km/h,30 km/h and 20 km/h for icy road.It was recommended to limit the speeds of 100 m/h,70 km/h and 40 km/h for dense fog when the visibility was 200 m,100m and 50 m respectively.The research results of this paper can provide reference for road traffic control departments in Beijing-Tianjin-Hebei and surrounding areas to prevent traffic accidents.