Influence Patterns of Urban Roads on Micro-scale Temperature Fields and Human Thermal Comfort

As a vital component of the urban underlying surface, roads significantly impact urban temperature and human thermal comfort according to their area proportion, material composition, and roadside vegetation status. In this study, micro-scale models that incorporate urban road scenes were constructed based on ENVI-met, and their effectiveness was validated through field measurements. The influences of urban road area proportion, pavement albedo, pavement thermal conductivity, and roadside vegetation coverage on micro-scale air temperature, mean radiation temperature, pavement temperature, and physiological equivalent temperature were investigated. Results showed that a 20% increase in the proportion of urban road area led to a temperature rise of 2.42 °C. A high albedo pavement resulted in an air temperature decrease of 1.38 °C. compared to that of an ordinary pavement at 14:00; however, the cooling effect at night was not pronounced. A low thermal-conductivity pavement effectively reduced nighttime pavement and air temperatures. Adding 10% roadside vegetation coverage decreased air temperature by 3 °-4 ° and physiological equivalent temperature by 0.3 °-1.4 °. Correlation analysis between thermal conductivity and air temperature revealed a coefficient of 0.714. Increasing roadside vegetation coverage to mitigate the urban heat island effect incurred a cost increase of 0.218%. Overall, a larger urban road area proportion leads to a more pronounced urban heat-island effect; however, this relationship is nonlinear. A high albedo pavement effectively lowers air temperature but does not enhance human thermal comfort. Thermal conductivity had the highest correlation with air temperature, making low thermal conductivity pavements favorable for nighttime micro-scale temperature and outdoor thermal comfort. Increasing roadside vegetation lowers micro-scale air temperature and physiological equivalent temperature, offering the best economic benefits and serving as an effective approach to alleviating the urban heat-island effect. The study contributes methods and insights for mitigating the urban heat-island effect from the road design perspective. © 2023 Xi'an Highway University. All rights reserved.