Influence of elevated walkways on outdoor thermal comfort in hot-humid climates based on on-site measurement and CFD modeling

The elevated walkway is commonly designed to facilitate pedestrian movement and alleviate traffic conflicts. Its shading effect is supposed to benefit outdoor thermal comfort on hot days, especially in hot and humid regions, but relevant research has been scarce. To validate this hypothesis, we conducted on-site measurements on an elevated walkway and ground sidewalks in Hong Kong during summer and winter. The parametric simulation study was performed to investigate the effects of the elevated walkway, street aspect ratio (H/W), walkway width (Wew), and sidewall type on outdoor thermal comfort in ideal urban street canyons through large eddy simulation and RayMan modeling. Results indicate that the elevated walkway increases the ground-level physiological equivalent temperature (PET) by up to 2.7 degrees C and causes a 2-17 degrees C lower walkway-level PET value. Ground -level and walkway-level PET values initially increase and then decrease with rising H/W but positively correlate with Wew. Compared to the open sidewall, the semi-hermetic sidewall decreases the ground-level PET value slightly (below 0.8 degrees C) but raises the walkway-level PET value (below 1.3 degrees C). This study confirms the efficacy of elevated walkways in improving pedestrian thermal comfort in hot weather, contributing to shade strategies for heat stress mitigation and thermal comfort improvement.