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The effect of screening on road surface temperatures is analysed using data from the Swedish road weather information system (RWIS) together with data from thermal mapping. The study deals with the analysis of temperature variations caused by shading of the road surface during clear daytime conditions and focuses on the relation between solar elevation and magnitude of road surface temperature differences between screened and sun‐exposed areas. Also included is an analysis of how the temperature differences during the day affect the establishment of temperature variations after sunset and the time it takes after sunset for temperature differences caused by shading to decline. The results show that the magnitude of road surface temperature differences between sun exposed and screened sites (RSTdiff) that develop during clear day conditions can be attributed to solar elevation (β) and can be expressed by the equation: RSTdiff = −2.7 + 0.46(β). A relationship between the daily maximum temperature difference and the preservation of the screening effect after sunset is observed. The effect after sunset can be described by: RSTdiff = A − B h + C h2 − D h3 − E h4 + F h5, where h is the time in hours after sunset and A to F are constants related to the time of the year at the actual site. Copyright © 2000 Royal Meteorological Society

The present study deals with the thermal mapping technique in a road climatological perspective. The temperature mapping technique is analysed in relation to instrument set‐ups, data collecting and possible sources of errors in converting measured radiation to surface temperature values. Furthermore, analyses of thermal mapping recordings are discussed. Factors that give rise to a varying temperature pattern are presented (i.e. road‐bed material, radiation and advection), and also how the thermal mapping technique can be used to determine the relative importance of these factors. The conclusion of the study is that the technique is very useful but it is very important to be aware of the limits and different source of errors involved. Copyright © 1999 Royal Meteorological Society

The aim of this paper is to describe how infrared thermography is used to analyse variation in road surface temperature during clear calm nights. Having knowledge of surface temperature variations along road stretches makes it possible to give an accurate survey of the risk of local slipperiness. The infrared equipment used is an Agema 870-system arranged on various kinds of platforms, stationary, car-and helicopter-mounted. Several factors are of importance in causing surface temperature variations, such as screening from the sun, variation in traffic intensity and construction materials of the road. This article reviews the influence of these factors on road surface temperature and how various platforms could be used to conduct detailed recordings. Sun screening by road rock cuts causes shadow patterns resulting in surface temperatures which are low when compared with sun exposed areas. Height and orientation of the screening object determine the intensity of the surface temperature difference. A maximum surface temperature variation after sunset of approximately 5'0°C was recorded. Road surface temperature differences also occur due to variation in traffic intensity. An intense traffic flow was found to affect the temperature by approximately I·O°C. Owing to different topographical surroundings and construction, bridges have been shown to differ in temperature when compared with adjoining roads. Variation in road bed material has also been proved to have a great effect on road surface temperature.