Optimizing Bus Stop Environments: Analysis of Sun Glare Reduction with Green Elements in MLS and GPR Data

Abstract. Urban transportation is pivotal in facilitating citizen mobility, and within this sphere, the thermal comfort experienced at bus stops significantly impacts pedestrians' well-being. This research delves into the analysis of direct sun glare at bus stops utilizing Mobile Laser Scanning (MLS) point clouds. Solar angles are calculated to evaluate sun rays, focusing particularly on the summer solstice, and considering the integration of trees to alleviate direct sun glare. The methodological approach comprises four stages: 1) Semantic segmentation of the bus stop environment, 2) Sun glare analysis, 3) Sun glare analysis integrating trees, and 4) Subsoil investigation with Ground-Penetrating Radar (GPR). Various algorithms, including DBSCAN and filters for height, width, and intensity, are employed to classify different elements contained in the bus stop. Sun rays are then derived based on sun angles, identifying intersections with street elements and vertical structures like bus stops or facades. Subsequently, these intersections are recalculated, incorporating trees in the bus stop vicinity. Finally, GPR is utilized to assess the viability of adding trees. Three bus stops in Vigo, Spain, serve as the focal points of analysis. The study delineates specific time intervals when sun rays either encounter new vegetation obstacles or remain unobstructed. While both small and large trees show potential in reducing sun glare, larger trees notably exhibit greater effectiveness in blocking sun glare for extended periods.