Objective In the context of health city construction, it is urgent to mitigate the negative impact of inappropriate greening on the use of living facilities, walking, recreation in green space, etc., so as to enhance the health benefits for citizens. Based on the renovation practice of Sandao Street in Chengdu, this research further discusses the following questions: How to rationally rearrange green spaces and functional spaces of pedestrian streets to balance the aesthetics and functionality thereof? To what extent can the increasing area of green spaces in streets affect people's decision-making on health-related behaviors? Can we maintain a high proportion of green spaces while optimizing functional spaces for walking, living facilities, green space recreation, etc.? If so, what principles should be followed in street greening arrangement?
Methods Based on the renovation practice of Sandao Street in Chengdu, this research, through eye movement behavior experiment, discusses the reasons and influencing mechanism for the formation of current street space pattern of excessive green spaces but insufficient functional spaces. Combining the behavioral intervention ladder and the eye movement experiment, the research explores the influence of visual attention on people's choice of living facilities beneficial to health. The first step is to verify what environmental information can attract people's attention in specific behavioral scenarios (use of living facilities, walking, recreation in green space, etc.). Second, will people be attracted by any environmental information show interest and preference for it? Third, how do people's differences in interests and preferences affect their final decision-making on health-related behaviors? Based on the behavioral intervention ladder theory, the experimental measurement of behaviors supported by eye movement can be divided into three parts. On the premise of controlling the proportion of green spaces in the environmental exposure, attention, interest and action can be measured separately. Attention and interest can be respectively measured by first fixation time and total fixation time in the eye movement experiment. Action can be measured by questionnaire.
Results The results of behavioral decision-making show that the greening transformation strategy of reducing the occlusion and adjusting the layout can not only ensure the green-looking ratio, but also significantly promote the use of facilities (from 26.25% to 78.75%), recreation in green space (from 47.50% to 68.75%), and walking intention (Experiment 1: from 35% to 85%; Experiment 2: from 25% to 75%). According to the results of the eye movement experiment, people are typically interested in the target elements such as ancillary commercial functional facilities (X=7, 552.34, S=5, 584.20) and street building interface (X=6, 878.48, S=5, 657.29), while street tree (OR=1.000, 134, p=0.014) in the decision-making process of facility use (p=0.014) and ground greening along the road (OR=1.000, 431, p=0.001) are taken as the core of greening transformation to improve the visibility of the target elements (ancillary commercial functional facilities and street building interface), and accordingly strengthen people's intention to conduct relevant activities. In the decision-making on recreation in green space, compared with the walking area (X= 3, 722.85, S=5, 000.20), the attached recreational facilities (X=88, 615.65, S=113, 001.18) and pedestrian crossing facilities (X=82, 090.53, S=134, 824.45) attract more interest despite the small picture proportion thereof. Compared with the inward-oriented layout, the ground greening along the road (OR=0.999, 716, p=0.038) in the perspective opposite the street occupies a relatively small field of view, which makes it more likely for target elements (attached recreational facilities) to attract people's attention, thus affecting people's decision to choose the outward-oriented green space as the recreation place in the perspective of opposite the street. Similar findings are supported by the impacts of walking activities, which provide an evidence-based perspective on street refinement and greening improvement with the goal of promoting health-related activities.
Conclusion In terms of street greening, the proportion of green spaces should not be the only consideration. Instead, we need to focus more on the relationship between street greening and functional facilities, and pay special efforts to prevent the bottom shrubs from blocking the view of the street interface leading to those facilities. The design of greenbelts entails not only the construction of street windows, but also the setting of necessary "blank area" that can help control the pruning height of the branches of the forest canopy, only so can key elements such as the building interface along the street and the attached commercial functions and facilities be highlighted. From the perspective of actual street health benefits, we should not only consider the perceived health benefits of green space itself, but also consider how it can lead to active participation of citizens. The greening design needs to balance the area of green spaces and the accessibility of site layout, so as to enhance people's intention of walking and recreation. However, this research, as a single case of evidence-based design research, shows limited practical value for other types of street reconstruction. For further improvement, future researches are supposed to incorporate more abundant street samples, and further discuss the health-related behaviors of citizens in a more systematic way. In addition, although the tabletop experiment based on scene photos can meet the standard of effective control over transformation conditions required by evidence-based research, it cannot simulate people's feelings for real street space. Therefore, in the future, experimental tools such as head-mounted eye movement and VR should also be incorporated into relevant researches.
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