Study on An Effective Roadway Watering Scheme for Mitigating Pedestrian Thermal Comfort According to the Street Configuration

Abstract

Continuous measurement of road surface temperature using an infrared camera throughout the summer season was conducted to clarify the duration of surface temperature decrease due to roadway watering according to weather conditions and watering time. Watering during sunny daytime conditions resulted in a maximum reduction in surface temperature of about 10 °C and an average reduction of about 6 °C. The duration of the surface temperature decrease was short (less than 30 min) for sunny days and long (more than 30 min) for cloudy days. On sunny days, if the evaporation rate was faster and the surface temperature decrease was larger, then the duration of the evaporation was shorter. Effective roadway watering plans were investigated according to the street configurations by simulating the thermal environment considering the solar radiation shielding condition of pedestrians on sidewalks. Simulation results in the downtown area of Kobe city indicated that watering the nearby roadways resulted in only 20% and 39% comfort for the northern sidewalks on the east–west road at 10:00 and 16:00, but about 70% comfort for the southern sidewalks and 60–90% comfort for the eastern and western sidewalks. Guiding pedestrians to a shaded sidewalk and then watering the nearby roadway to lower the surface temperature in the sun improves the thermal environment for pedestrians.