The renovation of public space environments in old residential areas has become the focal point in Chinese urban renewal and promotion of urban sustainable development; thus, an urgent need for research expansion is attached to identifying the environmental factors of public space and their impacts from the perspective of residents’ needs and satisfaction. Taking Hefei, China, as an example, and based on a satisfaction survey of the public space environment in old residential areas, this study discerned critical factors affecting public space satisfaction through gradient-boosting decision trees and impact-asymmetry analysis methods, after which the asymmetric relationship between public space environment factors and resident satisfaction was tested and the priority and goal of public space environment renovation were obtained. The results indicate that the following: (1) Compared with physical environment factors, current social environment factors, including uncivilized behavior, space occupation, and hygiene and cleanliness, exert a greater impact on the overall satisfaction. (2) The hypothesis that there exists a general nonlinear relationship between environmental factors and satisfaction is verified, with all social environment factors proving to be nonlinear and physical environment factors being highly related to social environment creation, such as nursing space for the old and young, reading and learning space, and display and communication space. (3) A priority hierarchy for the improvement of environmental factors should be established, which basically conforms to Maslow’s hierarchy of needs theory. The role of social environment renovation should be highlighted, along with the necessity to bolster community governance and public space management. At the level of the physical environment, more space should be available for the activities of residents, display and communication, and reading and learning. This study can provide a corresponding theoretical basis and planning inspiration for meeting the multiple needs of residents for public space, improving life happiness, and promoting the sustainable development of cities in the renovation of public space environments in old residential areas.

The difficulty of travel for the elderly is a challenge for urban management. Quantifying the satisfaction of public transport services from the perspective of the elderly is a people-oriented scientific research method. Based on the survey data of 2019 and 2020 and by selecting the interview data of people over retirement age before analyzing the non-linear relationship between bus service elements and elderly satisfaction by the impact-asymmetry analysis and gradient boosting decision trees, the optimization strategy of ground public transportation for the elderly in Harbin was obtained. The results show that the following five factors have the greatest impact on overall satisfaction, namely, site broadcasting, complaint handling, awning facilities, driver driving habits, and the punctuality of bus operation. Among them, “awning,” the “punctuality of bus operation,” and “drivers’ driving habits” should be given priority to improve. The conclusion of this study provides a theoretical basis for the accurate optimization of public transport services.

In the context of the global construction of low-carbon cities and residents’ pursuit of healthy living, the improvement in the urban walking environment has gradually been emphasized in the field of planning and transportation research. Using Harbin, China, as an example, this paper combines gradient boosting decision trees (GBDTs) and impact-asymmetry analysis (IAA) methods to explore the differences in residents’ preferences for the pedestrian environment needs in old and new urban areas, analyze the asymmetric relationship between walking environment factors and overall satisfaction, and provide a sound basis for the renewal and reconstruction of the walking environment in old urban areas and the improvement of the walking environment in new urban areas. The factors affecting the pedestrian environment in the old and new urban areas are similar and different, with the aesthetics and safety and the aesthetics and comfort of the pedestrian environment having a greater impact on the old and new urban areas, respectively. According to the results of the IAA, the old city should focus on improving green landscaping, street furniture, the uncivilized behavior of pedestrians, pavement encroachment, barrier-free facilities, and the speed of motor vehicles; the new city should focus on improving the building facade effect, the uncivilized behavior of pedestrians, and green landscaping.

Harbin, China, has a large population density and a large number of motor vehicles. To alleviate traffic congestion, based on the survey data of bike-sharing riders in the new and old urban areas of Harbin in May 2022, this paper uses an impact-asymmetric analysis and gradient enhancement decision tree to analyse the asymmetric relationship between bike-sharing travel environment elements and cyclists’ satisfaction, and the optimisation strategy for the bike-sharing riding environment was obtained so that more residents can choose to ride. This research shows that the infrastructure of the motorway in the old urban area had the greatest impact on the overall satisfaction, while the travel quality of the shared bikes in the new urban area had the greatest impact on the overall satisfaction. In addition, due to the differences in urban environments and satisfaction, planning directions are different when satisfying cyclists in the new and old urban areas. The old urban area should emphasise cycling comfort and road coherence to provide a good travel environment; however, the new urban area should focus on the operation of shared bikes to meet the needs of cyclists. Therefore, future research should formulate refined improvement strategies for different regions.

Active travel (walking and cycling) is a low-carbon travel mode, that is of great significance to the sustainable development of urban mobility. This paper integrates the mobility environment elements for walking and cycling, and constructs an environment for active travel evaluation index system. The main urban area of Harbin City is taken as the research object, and field research and interviews are conducted under the public health events. This study utilized the Gradient Boosting Decision Tree (GBDT) model to identify relatively important elements and employed the Impact-Asymmetry Analysis (IAA) method to explore the asymmetrical relationship between environment elements for active travel and the overall satisfaction. The goal is to identify key elements in the active travel environment that require optimization urgently and propose a strategy for optimizing the environment for active travel. The study found a non-linear relationship between the environmental elements of active travel and the overall satisfaction of residents. The study indicates that to enhance in residents’ satisfaction with the environment for active travel, the top priority should be improving the completeness of cycling road network, followed by pedestrian behavior and landscaping on sidewalks. The study further showed that there are differences in residents’ demand for walking and cycling environments, with residents more concerned about comfort for walking environments and more concerned about convenience for cycling environments.