2:30 PM - 2:45 PM
[HTT17-04] On Psychological Influence by Planting Street Trees for Pedestrians
Keywords:Street trees, Psychological Influence, Planting, comfort
IntroductionIn Japan, the number of street trees increased annually until 2002. However, the trend has since leveled off due to issues such as the growth of large-diameter trees. Street trees serve multiple functions by providing shade from the summer sun, mitigating exhaust emissions and noise, and contributing to the protection of roadside environments. They also help alleviate urban-specific phenomena such as the heat island effect. Although tree species that can withstand various harsh environments are selected, appropriate spacing has not always been established. Few municipalities have developed master plans for street trees, leading to inconsistent spacing across different regions. Additionally, some trees that appear healthy on the surface may suffer internal decay due to environmental factors, making removal unavoidable. This results in disruptions in the uniformity of tree spacing. With urban greening becoming increasingly important and city planning needing to ensure the coexistence of automobiles and pedestrians, redefining street tree spacing is necessary. The focus should be placed on pedestrians' psychological responses.
Purpose and Methods of the researchA review of academic studies on street tree spacing shows that Kawaguchi et al. evaluated the landscape and tree spacing of street trees using VR. Their study found a decline in six evaluation criteria when the spacing exceeded twenty meters, while the perception of "openness" improved. Based on these findings, they suggested a preferable spacing of up to fifteen meters. Suzuki et al. assessed the comfort of tree spacing using the fluctuation theory. Their research examined changes in attractiveness by varying the spacing according to the 1/f fluctuation principle. They found a significant impact on attractiveness in tree spacing patterns with moderate density, such as five–seventeen meters and five – twenty meters, when incorporating 1/f fluctuations. Although studies have evaluated the comfort of street tree spacing, research focusing on continuous eye movement and psychological aspects remains limited. This study aims to identify the optimal street tree spacing by analyzing pedestrians' gaze behavior.
Survey ResultsThe survey results showed that as the spacing between street trees increased, responses related to "speed," "automobiles," and "sidewalks" became more frequent, while references to "street trees" decreased. For the categories of "sky," "buildings," and "people," differences appeared in evaluation values, However significant changes were observed across different spacing conditions. In the evaluation of randomly spaced street trees, the perceived "speed" increased significantly compared to other regularly spaced arrangements. Even within regularly arranged tree placements, evaluation values varied significantly depending on factors such as the number of trees. This study clarifies the relationship between the planting street trees and the spatial moving elements.
Purpose and Methods of the researchA review of academic studies on street tree spacing shows that Kawaguchi et al. evaluated the landscape and tree spacing of street trees using VR. Their study found a decline in six evaluation criteria when the spacing exceeded twenty meters, while the perception of "openness" improved. Based on these findings, they suggested a preferable spacing of up to fifteen meters. Suzuki et al. assessed the comfort of tree spacing using the fluctuation theory. Their research examined changes in attractiveness by varying the spacing according to the 1/f fluctuation principle. They found a significant impact on attractiveness in tree spacing patterns with moderate density, such as five–seventeen meters and five – twenty meters, when incorporating 1/f fluctuations. Although studies have evaluated the comfort of street tree spacing, research focusing on continuous eye movement and psychological aspects remains limited. This study aims to identify the optimal street tree spacing by analyzing pedestrians' gaze behavior.
Survey ResultsThe survey results showed that as the spacing between street trees increased, responses related to "speed," "automobiles," and "sidewalks" became more frequent, while references to "street trees" decreased. For the categories of "sky," "buildings," and "people," differences appeared in evaluation values, However significant changes were observed across different spacing conditions. In the evaluation of randomly spaced street trees, the perceived "speed" increased significantly compared to other regularly spaced arrangements. Even within regularly arranged tree placements, evaluation values varied significantly depending on factors such as the number of trees. This study clarifies the relationship between the planting street trees and the spatial moving elements.