PUBLICATIONS LIST
*Corresponding author
50. Wang, J., Cheng, W., Lu, Y.*, & Wang, D. (2023). Effect of rail transit on travel behavior: A systematic review and meta-analysis. Transportation Research Part D: Transport and Environment, 122, 103882. (Click for full text of PDF)
Recent research has treated new rail transit systems as ‘natural experiments’, and while they have generally resulted in increased ridership, the underlying reasons for this remain unclear. To address this, we undertook a systematic review and meta-analysis of natural experiment studies published between 2000 and 2023 to synthesize the effect of rail transit on various travel behavior. We selected a total of sixteen studies for review, of which eight were suitable for meta-analysis. The pooled results showed that the introduction of rail transit significantly increased the mode share of rail while significantly decreasing the mode share of bus and car, and vehicle miles traveled (VMT). Our findings suggest that rail transit has the potential to promote sustainable travel behavior. However, to establish a more reliable association, further high-quality research is needed to examine the nuanced context, extend the follow-up duration, incorporate objective measures, and appropriately define the control group.
49. Wu, X., Lu, Y.*, Wang, J., & Jiang, B. (2023). Built Environment in Urban Space Affect Protests: A Cross-Sectional Study in Hong Kong. Sustainability, 15(17), 13096. (Click for full text of PDF)
The built environment is indispensable for conducting protests. However, we still know little about the role the built environment plays in either supporting or hindering protests. In this study, we investigated the relationship between built environment characteristics and the spatial distribution of 348 protests that occurred in Hong Kong from June 2019 to January 2020. We innovatively distinguished between peaceful and violent protests as well as legal and illegal (authorized vs. unauthorized) protests. Our study revealed several significant patterns. First, in general, areas with a higher level of building density, government and commerce point-of-interest (POI) density, metro accessibility, park density, and street greenery experienced more protesting activities. Second, illegal and violent protests, those which are less constrained by authorities and thus more likely to reflect the autonomous choices of the protestors, are more likely to occur in regions with more government and commercial buildings, high metro accessibility, and a high level of street greenery. Based on these findings, we also proposed a new framework to illustrate the relationship between certain built environment features and choice of protest locations, which we hope will provide preliminary guidance for future studies.
48. Yang, H., Wen, J.*, Lu, Y.*, & Peng, Q. (2023). A quasi-experimental study on the impact of park accessibility on the mental health of undergraduate students. Urban Forestry & Urban Greening, 127979. (Click for full text of PDF)
Public mental health issues have gained growing attention from academics and policymakers due to their increasing prevalence and multiple adverse and severe consequences. Although some studies have supported the benefits of parks on mental health, the causal relationship between park accessibility and mental health remains unclear. By converting a large cross-sectional sample of 22,060 undergraduates nationwide in China into a quasi-panel dataset, this study untangled the causal impact of park accessibility on mental health benefits. We employed a quasi-experimental research design and used a difference-in-difference (DID) model to estimate the causal effects of park accessibility on depression symptoms within varying buffer sizes (i.e., 0.5 km, 1 km, 1.5 km, and 2 km). Furthermore, propensity score matching (PSM) and the Heckman selection model were employed to mitigate the selection bias caused by the prior differences of the treatment group and the control group. The results revealed that park accessibility had a positive effect on mental health and that its influence decreased with increased buffer sizes. Regarding the gender and living-cost differences, park accessibility within the 0.5 km and 1 km buffers had a greater mental health impact on females than on males, and it had a greater impact on high-living cost undergraduates than on low-living cost undergraduates. To increase the mental health benefits of undergraduate students, this study suggests that the provision of parks within a 1 km radius buffer surrounding the campus should be a priority to improve the mental health of undergraduates.
47. Wu, X., Lu, Y.*, & Jiang, B. (2023). Built environment factors moderate pandemic fatigue in social distance during the COVID-19 pandemic: A nationwide longitudinal study in the United States. Landscape and Urban Planning, 233, 104690. (Click for full text of PDF)
Non-pharmaceutical interventions (NPIs) remain some of the most effective measures for coping with the ever-changing coronavirus disease 2019 (COVID-19) pandemic. Pandemic fatigue, which manifests as the declined willingness to follow the recommended protective behaviors (e.g., keeping social distance policies, wearing masks), has commanded increasing attention from researchers and policymakers after the prolonged NPIs and COVID-19 worldwide. However, long-term changes in pandemic fatigue are not well understood, especially amidst the ever-changing pandemic landscape. Built environment factors have been shown to positively affect mental and physical health, but it is still unclear whether built environments can moderate pandemic fatigue. In this study, we used Google mobility data to investigate longitudinal trends of pandemic fatigue in social distance since the onset of NPIs enforcement in the United States. The results indicated that pandemic fatigue continuously worsened over nearly two years of NPIs implementation, and a sharp increase occurred after the vaccination program began. Additionally, we detected a significant moderation effect of greenspace and urbanicity levels on pandemic fatigue. People living in areas with high levels of greenness or urbanicity experienced lower levels of pandemic fatigue. These findings not only shed new light on the effects of greenness and urbanicity on COVID-19 pandemic fatigue, but also provide evidence for developing more tailored and effective strategies to cope with pandemic fatigue.
46. Yang, Y., Peng, C., Yeung, C. Y., Ren, C.*, Luo, H., Lu, Y., Yip, P. S., & Webster, C. (2023). Moderation effect of visible urban greenery on the association between neighbourhood deprivation and subjective well-being: Evidence from Hong Kong. Landscape and Urban Planning, 231, 104660. (Click for full text of PDF)
The well-being benefit of urban greenery has been extensively documented broadly, though less is known about its moderation effect on the relationship between neighbourhood deprivation and subjective well-being. Some scholars also argued that the inconclusive associations between urban greenery and subjective well-being might be partially attributed to the various measuring methods of greenery and the difficulty to measure visible greenery objectively. In this study, we applied three approaches to objectively measure different aspects of urban greenery, including overall greenery by Normalized Difference Vegetation Index (NDVI), visible greenery by Google Street View (GSV) images, and park proximity by geospatial data. We captured two dimensions of neighbourhood deprivation: socio-economic disadvantage and social fragmentation. Using data from the first wave (2015) of the Hong Kong Panel Survey for Poverty Alleviation (N = 1752), the association between urban greenery, neighbourhood deprivation, and subjective well-being was investigated with multilevel linear regression models, while controlling other covariates. We found that subjective well-being level was negatively associated with social fragmentation but no socio-economic disadvantages, while positively associated with overall greenery and visible greenery. Additional moderation effect analysis reveals that the negative linkage between social fragmentation and subjective well-being was significantly mitigated by visible greenery. These findings demonstrated the importance of visible greenery in enhancing subjective well-being, especially for residents in deprived neighbourhoods, and offered new insights to support urban planning and public health strategies to create a healthy living environment.
45. Liu, D., Jiang, Y., Wang, R., & Lu, Y.* (2023). Establishing a citywide street tree inventory with street view images and computer vision techniques. Computers, Environment and Urban Systems, 100, 101924. (Click for full text of PDF)
Trees in urban areas have diverse ecological, social, and health benefits. The establishment of up-to-date and accurate street-tree inventories that list the species and locations of individual street trees is critical to urban tree management and tree-planting campaigns. However, street-tree inventories are incomplete or lacking altogether in most cities. This is partly because conventional field assessment is laborious or expensive. In this study, we developed and validated a novel and cost-effective method to establish a city-wide tree inventory based on computer vision and freely available street view images (SVIs). Tree information such as species, height, crown diameter, and geographical coordinates at the individual tree level can be assessed. Based on an object detection model, we adopted a species-based loss function to address the challenges of long-tailed class distribution of species, which is caused by imbalance among sample size of different tree species and can lead to poor performance of the model. Compared with other research in urban tree species recognition, the modified model shows a higher accuracy. In order to calculate quantitative features of street trees, we employed a deep learning algorithm, which is pretrained on stereo dataset and validated on Google Street View images, to estimate the depth of each pixel in SVIs. Furthermore, as a demonstration, we established the citywide tree inventory and conducted tree diversity analysis for Jinan, China. Compared with new developed area, the old town has more street trees and more diverse tree species which can improve biodiversity and walkability. We also found that plane trees, which can cause allergic reactions, are dominant in northern new developed urban area.
44. Xie, B., Pang, Z., He, D.*, Lu, Y.*, & Chen, Y. (2023). Effects of neighborhood environment on different aspects of greenway use: Evidence from East Lake Greenway, China. Journal of Transport Geography, 106, 103488. (Click for full text of PDF)
As a component of both urban transport infrastructures and green spaces, urban greenways play a vital role in connecting urban public spaces, promoting active travel, and facilitating population-level health outcomes. Recently, there has been considerable interest in illustrating the determinants of greenway use in various contexts. Nevertheless, most studies have failed to identify the different aspects of greenway use. Meanwhile, the potential significance of residential neighborhood environments in utilizing greenways has largely been overlooked. In this study, we analyzed data collected from 1020 residents living around the East Lake Greenway in Wuhan, China, to discern three aspects of greenway use: frequency, time, and intensity. In addition, we investigated the moderate effect of neighborhood environmental characteristics on the association between greenway proximity and different aspects of use. After controlling for covariates, multi-level regression models showed that greenway proximity and neighborhood environmental characteristics were significantly associated with greenway use, while the specific associations varied across different aspects of greenway use. Furthermore, proportion of residential land, floor area ratio, and street connectivity moderated the relationship between greenway proximity and greenway use. In summary, the findings of this study contributed to the planning and management of greenways in high-density cities.
43. Wang, J., Lu, Y.*, Yang, Y., Peng, J., Liu, Y., & Yang, L. (2023). Influence of a new rail transit line on travel behavior: Evidence from repeated cross-sectional surveys in Hong Kong. Journal of Transport Geography, 106, 103526. (Click for full text of PDF)
It has been well established that the infrastructural development for rail transit stimulates rail transit use. However, there is little agreement about the source of the increased rail transit use. Using data from two repeated cross-sectional surveys, we examine changes in individual travel behavior resulting from the introduction of a rail transit line in Hong Kong. To address some methodological limitations inherent to repeated cross-sectional research design (e.g., selection bias and longitudinal incomparability), a two-dimensional propensity score matching method (2DPSM) is adopted to pair samples between the treatment and control groups in both cross-sectional and longitudinal dimensions. Paired t-tests are used to compare the longitudinal changes in travel behavior between the treatment and control groups of the matched samples. To get a more comprehensive understanding of the net treatment effects of the new rail line on travel behavior, we examined its impacts on both home-based trips (trips originating or terminating at home) and all trips for both treatment and control group. For home-based trips, the opening of the new rail line increased the rail mode share by 10.4%, and rail trip number by 0.126 (in terms of net effect, i.e., difference in the change between treatment and control group). It reduced the bus mode share by 17.1% and bus trip number by 0.208, showing a significant bus-to-rail modal shift. For all trips, the new rail line increased rail mode share by 9.5% and total trip number by 0.189. It also decreased bus mode share by 13.2%, and bus trip number by 0.191. Hence, the source of the increased rail transit use came from both the modal shift from bus and the increased travel demand induced by the new transit infrastructure. For both home-based trip and all trips, there was no significant influence on car use and total trip distance. Our findings provide new evidence that the development of rail transit in a high-density urban setting encourages a modal shift from bus to rail transit and stimulates flexible travel behaviors, but fails to control private vehicle use.
42. Jiang, B., Yang, Y., Chen, L., Liu, X., Wu, X., Chen, B., Webster, C., Sullivan, W. C., Larsen, L., Wang, J., & Lu, Y.* (2022). Green spaces, especially nearby forest, may reduce the SARS-CoV-2 infection rate: A nationwide study in the United States. Landscape and urban planning, 228, 104583. (Click for full text of PDF)
The coronavirus pandemic is an ongoing global crisis that has profoundly harmed public health. Although studies found exposure to green spaces can provide multiple health benefits, the relationship between exposure to green spaces and the SARS-CoV-2 infection rate is unclear. This is a critical knowledge gap for research and practice. In this study, we examined the relationship between total green space, seven types of green space, and a year of SARS-CoV-2 infection data across 3,108 counties in the contiguous United States, after controlling for spatial autocorrelation and multiple types of covariates. First, we examined the association between total green space and SARS-CoV-2 infection rate. Next, we examined the association between different types of green space and SARS-CoV-2 infection rate. Then, we examined forest–infection rate association across five time periods and five urbanicity levels. Lastly, we examined the association between infection rate and population-weighted exposure to forest at varying buffer distances (100 m to 4 km). We found that total green space was negative associated with the SARS-CoV-2 infection rate. Furthermore, two forest variables (forest outside park and forest inside park) had the strongest negative association with the infection rate, while open space variables had mixed associations with the infection rate. Forest outside park was more effective than forest inside park. The optimal buffer distances associated with lowest infection rate are within 1,200 m for forest outside park and within 600 m for forest inside park. Altogether, the findings suggest that green spaces, especially nearby forest, may significantly mitigate risk of SARS-CoV-2 infection.
41. He, D., Lu, Y.*, Xie, B.*, & Helbich, M. (2022). How greenway exposure reduces body weight: A natural experiment in China. Landscape and Urban Planning, 226, 104502. (Click for full text of PDF)
Access to public greenspaces is assumed to influence peoples’ body weight. However, causal evidence on this topic is limited, especially in developing countries. Using natural experiment approach, this study assessed 1) to what extent peoples’ body mass index (BMI) changed following a greenway intervention, and 2) potential gender disparities in both direct effects and underlying mediating pathways linking greenway exposure and BMI changes. Baseline and follow-up survey data on 1,020 adults were collected before and after the completion of East Lake greenway in Wuhan, China. Participants were split into treatment and control groups based on a 2 km threshold distance from housing estates to the greenway. Difference-in-difference (DID) estimations and structural equation models were used to assess the effects and pathways between the greenway intervention and BMI changes. The results showed that treatment group experienced a minor BMI reduction, while the BMI increased in the control group. DID models indicated that the effects of the greenway intervention on BMI changes are significant for both men and women. We also found distinct mediating mechanisms across gender. Changes in moderate to vigorous physical activity (MVPA) mediated the association between the greenway intervention and a reduction in BMI among men, while mental health changes mediated the association for women. Our findings provided compelling evidence that exposure to greenway prevents body weight increase and strengthened the rationale for green infrastructure investments to enhance public health in high-density cities.