STUDY ON LOW TEMPERATURE DIFFERENCES BETWEEN ROAD SURFACE AND BRIDGE SURFACE ON YANGZHOU-LIYANG EXPRESSWAY IN WINTER

WANG Jing; ZHU Cheng-ying; YUAN Cheng-song; BAO Yun-xuan

doi:10.16032/j.issn.1004-4965.2018.02.014

Abstract：Based on the minutely observed data of traffic weather monitoring stations during the period from 2012 to 2015 along the Runyang Bridge on Yangli expressway in Jiangsu province and the hourly data of the conventional meteorological stations,after analysis of the data,the pattern of low temperature distribution difference between the road surface and the bridge surface in winter and their causes of formation were discussed.The results are shown as follows:(1) Under the same weather conditions in winter,the bridge surface temperature was lower than the road and the ground.The maximum difference of the temperature between bridge surface and road surface was-5.7 ℃,which appeared nearly lh earlier than the time when the lowest temperature was reached.(2) The daily bridge surface temperature changes were similar under different weather conditions with the largest magnitude in fine days,followed in turn by overcast and rainy days,and the least magnitude in snowy days.Generally,the bridge surface was below 0 ℃ about 2 h earlier than the road surface,and maintained low temperature longer than the latter by about 3 h.The bridge surface temperature was lower than that of the adjacent road surface by about 2 ℃ during low-temperature period.(3) The average cooling rate of bridge surface temperature was similar in clear,overcast and rainy days,an order of magnitude larger than that of the snowy days.The average cooling rate of bridge surface temperature was significantly higher than that of road surface temperature under the same weather conditions.(4) The heat flux of the bridge surface was biggest in clear (-55.6 W/m2) days,followed by overcast and rainy days,and the least in snowy days (half of the clear days).Under the four kinds of weather conditions,the difference of the heat flux between the bridge and road surface was about-10 W/m2,showing that the dropping range of heat flux of the bridge surface is more than that of the road surface.Influencing the road surface temperature at night,the road subgrade thermal compensation effect was stronger than the air on the latent heat transfer and heat transfer fluid movement,so the icing conditions of the bridge surface was better than the road surface and the icing time of the bridge surface was earlier.