Jiahua Yu
Hao Zhang
Jing Shen- Department of Physical Education, China University of Geosciences (Beijing), Beijing, China
Background: Street greenery may have a profound effect on residents’ active travel (AT), a mode of transportation involving walking and cycling. This study systematically reviewed the scientific evidence on the effects of street greenery on active travel.
Methods: A comprehensive search was performed using keywords and references in PubMed, Web of Science, Scopus, and Cochrane Library. The review included studies that met the following criteria: (1) Study design: experimental studies, cross sectional studies, (2) Participants: individuals of all ages, (3) Exposure variables: street greenery, including street vegetation (e.g., trees, shrubs, and lawns), (4) Outcomes: active travel behaviors (walking, cycling), (5) Article type: peer-reviewed articles, (6) Search time window: from the inception of relevant electronic literature database until 21 June 2023, (7) Geographic scope: worldwide; (8) Language: articles in English.
Results: Twenty-six cross-sectional studies met the inclusion criteria and were analyzed. These studies employed objective metrics for assessing street greenery and varied methodologies to measure AT, including 14 using subjective measurements (like self-reported surveys), 10 using objective data (such as mobile app analytics), and two studies combined both approaches. This review identifies a generally positive impact of street greenery on active travel in various aspects. However, the extent of this influence varies with factors such as temporal factors (weekdays vs. weekends), demographic segments (age and gender), proximity parameters (buffer distances), and green space quantification techniques. Street greenness promotes active travel by enhancing environmental esthetics, safety, and comfort, while also improving air quality, reducing noise, and fostering social interactions. In addition, the study suggests that variables like weather, seasonality, and cultural context may also correlate with the effectiveness of street greenery in encouraging active travel.
Conclusion: Street greenery positively influences active travel, contributing to public health and environmental sustainability. However, the findings also indicate the need for more granular, experimental, and longitudinal studies to better understand this relationship and the underlying mechanisms. These insights are pivotal for urban planners and policymakers in optimizing green infrastructure to promote active transportation, taking into account local demographics, socio-economic factors, and urban design.
1 Introduction
Active travel refers to a mode of transportation that primarily involves physical activities such as walking and cycling during leisure activities or commuting. This modality offers multifaceted health benefits, including the mitigation of chronic disease prevalence, reduction in premature mortality, and alleviation of depression risk (1, 2). Beyond personal health, active travel yields substantial environmental advantages by diminishing air pollution and easing traffic congestion, thereby contributing significantly to environmental preservation (3–6). Furthermore, it enhances social cohesion by fostering community interactions, accruing extensive societal advantages (7, 8).
Although there exists a wide consensus on the benefits of active commuting, the prevalence of bicycle usage in developing countries like China has rapidly declined over recent decades. This decline is linked to a constellation of factors, including rapid urbanization, technological progress, and lifestyle shifts (9). The configuration of the urban environment exert a profound influence on patterns of active travel (10). Urban design elements, including the configuration of streets, the presence of sidewalks, and the availability of safe and comfortable pathways, are pivotal in shaping individuals’ decisions to engage in walking or cycling (11). In this vein, street greenery emerges as an integral element of urban green infrastructure, significantly contributing to the visual appeal of urban landscapes (12). Its role in encouraging active travel has gained recognition, drawing considerable scholarly interest (13). Consequently, many cities in various countries have been channeling investments into the enhancement and upkeep of green spaces, aiming to elevate residents’ quality of life (14).
Street greenery, which includes the integration of vegetation such as trees, shrubs, lawns, and green walls into the streetscape, enhance the esthetic and functional appeal of urban thoroughfares (15). Empirical evidence suggests that well-implemented street greenery initiatives significantly boost the duration and frequency with which residents engage in walking and cycling (15–18). The effectiveness of street greenery in promoting active travel is likely rooted in its capacity to enhance the visual appeal of urban environments, offering shade and cooler temperatures, which collectively contribute to increased comfort for pedestrians and cyclists (19, 20). This phenomenon can be understood through three key intermediary mechanisms. Firstly, street greenery contributes to creating an esthetically pleasing and comfortable environment, which has been shown to influence route choice and walking behavior positively. This is supported by research that highlights the importance of well-designed and high-quality community structures in encouraging active travel (21). By enhancing pedestrian pathways and beautifying community spaces, street greenery renders these areas more attractive, thereby fostering environments conducive to recreational and active travel behaviors. Secondly, the improvement of air quality and reduction of noise levels play a crucial role in facilitating active travel. A range of studies has demonstrated the adverse effects of subjective noise perception and PM2.5 exposure on individuals’ satisfaction with their travel experiences (22–24). A specific study elucidates how exposure to green streets can both directly and indirectly augment walking satisfaction among residents (25). It reveals that mitigating factors such as noise and PM2.5 levels are significant, underlining the direct positive influence of street greenery on walking satisfaction, as well as its indirect benefits through environmental enhancements. Improved air quality not only boosts energy levels and cognitive focus but also aids in mitigating the risk of neurological abnormalities (26). Moreover, a serene ambiance, achieved by reducing noise disturbances, provides a more enjoyable experience for active travelers, thereby encouraging them to incorporate active modes of transportation into their daily routines (27). Furthermore, street vegetation acts as a natural buffer against air and noise pollution, thereby creating an inviting and conducive environment for active travel (25). Finally, street greenery supports social interactions and fosters a sense of community, offering residents additional reasons to opt for walking, biking, and other active travel modes (28). Understanding these mediating mechanisms is crucial in discerning the multifaceted ways through which street greenery can influence active travel. By improving the esthetic appeal, environmental quality, and social cohesiveness of urban communities, street greenery initiatives can significantly promote sustainable active travel behaviors.
Nonetheless, the precise nature of the relationship between street greenery and active travel remains elusive, with the current body of research presenting a disjointed picture. Some studies assert a strong positive association (15, 29), while others report negligible or no correlation (30–32). These discrepancies could stem from methodological divergences, varying metrics for evaluating street greenery, or differing population demographics.
This review systematically examines the impact of street greenery on active travel. Our aim is threefold: First, we synthesize existing research to identify patterns and differences in findings, thereby elucidating the relationship between street greenery and active travel. Second, we critically analyze these studies to identify gaps and methodological limitations, setting the stage for future detailed investigations. Lastly, we aim to provide urban planners and policymakers with concrete insights about the role of street greenery in promoting pedestrian and cycling activities. This will assist in leveraging green infrastructure for active transportation, ultimately contributing to public health, environmental sustainability, and urban space enhancement. The primary purpose of this study, therefore, is to provide a comprehensive understanding of how street greenery influences active travel and to inform the development of effective urban planning strategies.
2 Methods
The current research adhered to the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (33).
2.1 Study selection criteria
This systematic review included studies based on a comprehensive set of inclusion criteria: (1) study design: experimental design, cross-sectional studies; (2) participants: individuals from all age groups; (3) exposure variable: street greenness, street vegetation such as trees, shrubs and lawns; (4) outcome measures: active travel behaviors, such as walking, cycling; (5) article type: peer-reviewed articles; (6) retrieval time window: from the inception of the relevant electronic bibliographic database until 21 June 2023; (7) geographical scope: global scale; (8) language: articles written in English.
The exclusion criteria were as follows: (1) studies that did not directly address active travel behaviors, such as walking or cycling; (2) studies did not involve street greenness; (3) studies published in a language other than English, to maintain linguistic consistency and facilitate uniform analysis; (4) the document type was a letter, editorial, research or review proposal, or a review article, as these types of documents typically do not provide original empirical findings.
2.2 Search strategy
A search for relevant keywords was executed across four major electronic bibliographic databases, namely PubMed, Web of Science, Scopus, and Cochrane Library. The search strategy encompassed all potential permutations of keywords associated with the three specified categories: (1) “street,” “eye-level,” “streetscape,” “street-level,” “street-side”; (2) “greenspace,” “greenspaces,” “green-space,” “green space,” “green spaces,” “green infrastructure,” “green infrastructures,” “green area,” “green areas,” “green belt,” “green belts,” “green environment,” “green environments,” “greening project,” “green element,” “green elements,” “urban green,” “greenery,” “greenness,” “greenbelt,” “greener,” “natural element,” “natural elements,” “natural environment,” “natural environments,” “natural outdoor environment,” “natural outdoor environments,” “natural surroundings,” “natural space,” “natural spaces,” “natural area,” “natural areas,” “natural land,” “open space,” “open spaces,” “open land,” “open area,” “open areas,” “walkable area,” “walkable areas,” “vegetated area,” “vegetated areas,” “public space,” “public spaces,” “public area,” “public areas,” “public land,” “nature,” “vegetation,” “park,” “parks,” “parkland,” “garden,” “gardens,” “tree,” “trees,” “landscape,” “woodland,” “woodlands,” “walkability”; (3) “active travel,” “bike,” “biking,” “bicycle,” “bicycling,” “cycling,” “active school transport,” “active transport,” “active transportation,” “active transit,” “active commuting,” “travel mode.” In the PubMed database, we utilized the “[TIAB]” tag to execute a thorough keyword search, ensuring that the title and abstract of the articles were meticulously combed for relevant terms. For the Web of Science database, we engaged the TS = Topic search tool, which extends the search through the article’s title, abstract, keywords, and Keywords Plus fields, providing a broad sweep across diverse academic disciplines. This search strategy set the stage for an intensive initial review phase. During this phase, the articles retrieved via keywords underwent a detailed evaluation against our stringent study selection criteria, based on their titles and abstracts. Those articles exhibiting preliminary signs of relevance were advanced to the next level for an in-depth full-text review. To maintain objectivity and thoroughness, this preliminary filtering process was independently conducted by two of the co-authors involved in this review. The concordance rate between the reviewers was quantified using Cohen’s kappa statistic, which yielded a substantial agreement score of κ = 0.77. Any discrepancies were resolved by consulting a third co-author.
To ensure the exhaustive coverage of literature, we conducted a meticulous backward and forward reference search, examining the reference lists of the selected full-text articles and tracking their citation trails. This bidirectional search allowed us to identify and incorporate studies that may not have been captured through keyword searches alone. Each article surfaced from this recursive search underwent a stringent screening using the same selection criteria established for the initial review. This iterative process was repeated until saturation was reached, with no further pertinent articles emerging.
2.3 Data extraction and preparation
Data from each article was meticulously collated using a uniform data extraction template. The table facilitated the systematic collection of vital information, including the author(s)’ names, year of publication, country of study, design methodology, sample size, participant age range, proportion of female participants, sample characteristics, statistical model, control variables, type of street greenness measure, detailed measure of street greenness, type of active travel measure, and detailed measure of active travel.
2.4 Data synthesis
The data compilation for this review was meticulously orchestrated by two co-authors. Our report encapsulates a detailed synthesis of the prominent themes and insights derived from the analyzed studies. The methodical procedures of data acquisition, thematic delineation, and synthesis were independently executed by two co-authors. Encountered discrepancies were diligently reconciled through a consultative discourse involving a third co-author, thereby upholding the analytical coherence of our review.
2.5 Study quality assessment
We appraised the methodological soundness of each study using the National Institutes of Health’s Observational Cohort and Cross-sectional Study Quality Assessment Tool, which assesses studies against a set of 14 criteria. For each criterion met, a study was awarded a point (“yes”), with no points given for unmet criteria (“no,” “not applicable,” “not reported,” or “indeterminate”). The cumulative points for all criteria yield a study’s overall quality score, which ranges from 0 to 14. This quality assessment, while crucial for evaluating the strength of the evidence presented, did not influence the decision to include studies in our review. Discrepancies in the quality assessment conducted by two co-authors were resolved through a consultative process with a third co-author, ensuring an unbiased and consistent evaluation.
3 Results
3.1 Identification of studies
Figure 1 illustrates the study selection process. A total of 3,285 articles were initially identified through keyword searches and reference screening. After removal of duplicates (880 articles), the remaining 2,405 articles underwent title and abstract screening, resulting in the exclusion of 2,369 articles. Subsequently, a full-text review was conducted on the remaining 36 articles in accordance with the study selection criteria. Among these, 10 articles were excluded. The primary reasons for exclusion included a lack of street greenery data in the articles, absence of reported outcomes regarding active travel. As a result, the final analysis comprised 26 studies that investigated the influence of street greenery on active travel (13, 15–18, 25, 29–32, 34–49).
Figure 1. Study selection flowchart.
3.2 Basic characteristics of the included studies
Table 1 summarizes the fundamental characteristics of the literature incorporated in this study. All studies adopted a cross-sectional study design. In total, this review encompasses 26 studies, with 19 of them originating from China. Among these, 11 were conducted in mainland China, while the remaining 8 were carried out in Hong Kong, China. Additionally, 3 studies were conducted in the United States, with 1 study each conducted in the United Kingdom, Spain, the Netherlands, and Korea. All the included studies were published in 2015 or later, with 1 study published in 2015, 4 studies in 2018, 2019, 2020, 2022, and 2023, and 5 studies in 2021. Among the 26 studies included in the analysis, there is considerable variation in sample sizes. Eight studies had sample sizes ranging from 127 to 999 participants. Six studies had sample sizes between 1,000 and 9,999 participants, while five studies had sample sizes exceeding 10,000 participants. Five studies reported trip records as their sample size, ranging from nearly 140,000 to 20 million records. The remaining two studies did not report their sample sizes. Among these studies, one focused on a university student population, five concentrated on adults, and four specifically studied the older adults. Residents from various age groups, while seven studies did not report the characteristics of the study sample. With the exception of eight studies that did not report gender ratios, all studies included both male and female participants, with a generally balanced gender distribution. These studies applied a variety of statistical models, including logistic regression, continuous regression, spatial error regression, multilevel logistic regression, multilevel linear regression, geographically weighted regression, binary logistic regression, ordinary least square models, structural equation models, and multivariate Poisson regression models. Most studies utilized individual socio-demographic information, such as age, gender, occupation, household income, as control variables. Some studies also incorporated control variables such as population density, street intersection density, land use mix, and others.
Table 1. Basic characteristics of the studies included in the review.
Table 2 provides a comprehensive overview of the measurement methods used in the included studies for assessing street greenness and active travel. It also highlights the specific variables related to these street greenness and active travel. Across all 26 studies, objective measurement were employed to assess street greenness. In particular, 10 studies used data sourced from Google Street View images, nine studies relied on Baidu street view maps, two studies utilized Tencent street view Map, and the remaining five studies employed various other objective measurement, including data from EnviroAtlas, GPS tracking points obtained through the MOVES smartphone app, and information accessed from Amsterdam’s data portal. The specific indicators used to assess street greenness primarily focused on eye-level street greenness, evaluated using the Green View Index (GVI). Other indicators encompassed metrics such as street tree density, street tree cover, sidewalk tree cover, and greenway proximity. Regarding active travel, it primarily encompassed walking (n = 13), cycling (n = 6), and active transportation (n = 7). Data related to active travel were drawn from a variety of sources, including large-scale survey like the London Travel Demand survey (n = 1), the Hong Kong Travel Characteristics Survey (n = 5), survey of the Health of Wisconsin (n = 1), the National Household Travel Survey (n = 1), and the Dutch National Travel Survey (n = 1); self-reported questionnaire (n = 6), with two of them using the International Physical Activity Questionnaire; objective measurement (n = 8), with two utilizing smartphone app, five obtained from bike-sharing companies, and one obtained from Strava; Additionally, the remaining two studies adopted a combined approach, incorporating both objective data obtained from GPS tracking and subjective travel diaries.
Table 2. Measures of street greenness and active travel in the studies included in the review.
3.3 Key findings
Table 3 presents the key findings derived from the included studies, elucidating the intricate relationship between street greenness and active travel behavior. We provide a concise summary of how street greenness influences various facets of active travel, encompassing factors like active travel duration or distance, the probability of active travel engagement, active travel frequency, and active travel satisfaction.
Table 3. Estimated effects of street greenness on active travel in the studies included in the review.
3.3.1 Street greenness and active travel duration, distance
Eleven studies were conducted to investigate the influence of street greenness on active travel distance or time (13, 15, 17, 18, 31, 34, 36, 39–41, 49). The findings revealed a positive correlation between street tree density and both walking distance (34) and walking duration (39). Notably, eye-level greenness, as indicated by the GVI, exhibited a significant relationship with extended walking durations within various buffer zones, including 400 m (13, 36), 500 m (41), 800 m (13, 15, 36, 40), and 1,600 m (47), for both utilitarian and leisure walking (45), particularly during weekends (49). Moreover, the cumulative GVI demonstrated a significantly positive correlation with active travel distance (31). However, it should be noted that the impact of street greenness on walking duration varies depending on the measurement, features, or weekdays/weekends. For instance, the mean Green View Index was found to have a significant negative effect on walking and bicycle travel distance (43). Furthermore, factors such as good greenway proximity and street-level betweenness did not show a significant association with walking distance or greenway utilization time (17, 34). Additionally, on weekdays, street greenness was not significantly related to walking duration (49), The impact of street greenery exhibits spatial variability, with a notably more pronounced effect observed in suburban areas (13).
3.3.2 Street greenness and the odds of active travel engagement
Nine studies have investigated the relationship between street greenness and the likelihood of active travel engagement. These studies have yielded significant findings, with five of them specifically examining the influence of street greenness on the probability of walking behavior (15, 34, 36, 40, 46), one focused on its impact on cycling behavior (38), and three shedding light on its effects on the likelihood of engaging in active transportation (16, 17, 45). The research results consistently demonstrate a positive association between various aspects of street greenness and active travel. Firstly, a higher density of street trees was found to be consistently linked to an increased likelihood of walking (34). Additionally, eye-level greenness or street greenery were significantly associated with a higher probability of walking, particularly within 150 m (46), 400 m (36), and 800 m buffers (15, 36, 40). In the context of cycling, the odds of cycling were positively correlated with eye-level street greenness across three buffer zones: 400 meters, 800 meters, and 1,600 m (38). Furthermore, the probability of participating in active transportation showed a positive relationship with sidewalk tree cover across various network buffers, including 500, 750, 1,000, and 1,250 m. Moreover, the mean GVI was found to significantly increase the likelihood of engaging in active travel (31). Interestingly, street tree cover exhibited a positive association with active transportation, particularly within network buffers spanning 750 to 1,250 m. However, it is worth noting that street tree cover did not show a significant association with active transportation within the 500-m buffer (30). Intriguingly, as the accumulated value of the GVI increased, it was inversely related to the probability of active travel engagement (31).
3.3.3 Street greenness and the frequency of active travel
Three studies have delved into the impact of street greenness on cycling frequency or greenway utilization frequency (16, 17, 47). Among these investigations, eye-level greenness emerged as a key factor, demonstrating a remarkable effect on cycling behavior. Notably, the effect of eye-level greenness on cycling frequency was found to be more pronounced on weekends than on weekdays (16). Additionally, street-view greenness and the level of greenway enclosure were positively correlated with increased cycling frequency, regardless of whether it was a weekday or a weekend (47). However, an intriguing finding emerged regarding the openness of the greenway. This factor seemed to yield divergent effects on cycling frequency depending on the day of the week. While high levels of greenway openness appeared to promote cycling on weekends, they potentially hindered it on weekdays (47). In contrast, greenway proximity demonstrated a somewhat unexpected trend. Greater proximity to greenways was negatively associated with greenway utilization frequency, implying that the convenience of access did not necessarily translate into higher usage of greenways (17).
3.3.4 Street greenness and active travel satisfaction
Two studies have undertaken an examination of the impact of street greenness on satisfaction related to active travel (25, 43). Notably, exposure to green spaces was discovered to wield a substantial influence on the walking satisfaction (43). Moreover, it was discerned that street greenness exposure not only carries a notable direct effect on the level of satisfaction associated with walking, but also yields a significant indirect effect on walking satisfaction through the mediation of physical activity, social interaction, and subjective environmental annoyances, including noise and PM2.5-related annoyances (25).
3.4 Study quality assessment
Table 4 presents the detailed and overall quality ratings derived from the study quality assessment. On average, the studies achieved a score of 8.19, with a range from 7 to 9. Each study rigorously formulated its research questions and objectives, clearly defined the study population, adjusted for crucial potential confounding variables that could impact the relationship between exposure and outcomes, and ensured a minimum participation rate of 50%. The attrition rate was uniformly recorded at 20% or less across all 26 studies. During the same time period, participants were recruited from populations that were comparable or similar, with strict adherence to a set of predefined inclusion and exclusion criteria that were applied consistently across studies. Most of the studies (n = 21) examined different levels of the exposure as related to the outcome. Worth noting is that none of the 26 studies assessed the exposure of interest before outcome measurement, provided a sample size justification, power description, or variance and effect estimates, maintained a blinded status concerning the exposure status of participants. The research methodologies employed by the studies featured in this comprehensive review predominantly adhered to a cross-sectional design, entailing a solitary assessment during the study period, thereby precluding the ability to discern any temporal association between exposure and outcomes.
Table 4. Study quality assessment.
4 Discussion
This systematic review comprehensively examines the impact of street greenery on active travel, drawing insights from 26 cross-sectional studies. The term “street greenery” refers to a variety of urban design features, such as street trees, planting strips, lawns, flower beds, pedestrian pathways, hedges, and green barriers. Active travel is defined to encompass walking and cycling behaviors, with data derived from both objective measures, such as mobile app data and bike-sharing, and subjective measures, including self-reported questionnaires. The findings indicate that a substantial proportion of the studies report a positive impact of street greenery on active travel. Nonetheless, the strength of this relationship appears to be modulated by various factors, including day of the week, age demographics, gender, the proximity of greenery, and the method of quantifying green spaces. Mechanistically, street greenery is posited to promote active travel through the creation of visually attractive, safe, and comfortable green environments, coupled with improvements in air quality, noise reduction, and facilitation of social engagement.
In our comprehensive review of 26 studies, 19 of them revealed a positive correlation between street greenery and various aspects of active travel, including the duration and distance of travel, participation probability, frequency, and satisfaction. These findings align with prior research, emphasizing the positive impact of green spaces on physical activity among Chinese adults (50) and associating street greenery with increased active commuting (51). However, inconsistencies surfaced across different variables, primarily attributed to variations in measurement methods. The choice of cumulative GVI and Mean GVI resulted in conflicting outcomes regarding the influence of street greenery on walking distance (31). Similar discrepancies arose in the probability of active travel participation, influenced by the measurement approach used (31). Additionally, disparities related to measurement periods, such as the positive correlation of eye-level greenness with weekend walking time but not on weekdays (49), and varying outcomes in different buffer zones (16, 36, 38, 49), underscore the nuanced impact of street greenery on active travel behavior. These inconsistencies may be attributed to regional disparities in geography, climate, culture, transportation infrastructure, and local travel habits.
Research highlights significant seasonal variations in residents’ active travel behaviors (30). Notably, active travel participation is substantially higher during non-winter months as compared to winter. This trend is attributed to the challenging conditions posed by colder temperatures and inclement weather in winter, which deter residents from engaging in active transportation (52). The seasonal dynamics of street greenery, which involves a range of plants, grasses, and trees, also play a pivotal role. In temperate climates, the visual appeal of street greenery changes with the seasons; spring and summer showcase lush vegetation and a high density of greenery, enhancing eye-level green visualization. Conversely, fall and winter see a reduction in this green vibrancy, as most plants, barring evergreens, shed their leaves and enter dormancy, leading to diminished eye-level greenness. This seasonal fluctuation in greenery may contribute to the observed seasonal differences in active travel, necessitating further research to understand its impact more comprehensively. Moreover, studies in environmental psychology have identified cultural and racial variations in leisure activities within green spaces (53–55), in the types of leisure activities engaged in the landscape. For example, one study (56) indicates differing patterns of park usage among American ethnic groups, with Hispanics typically engaging in more sedentary activities, while Whites often prefer walking or jogging, focusing on the esthetic aspects of parks. In contrast, Chinese residents frequently view parks as social gathering spaces, showing a preference for larger green areas with extensive recreational amenities and high-quality design (57). This suggests that cultural backgrounds significantly influence how green spaces are utilized, as further evidenced by a study (58) indicating that park usage in urban Hong Kong contrasts markedly with Western norms, possibly due to ethnic influences on recreational choices (59). Finally, the relationship between environmental amenities and active travel is also influenced by socio-economic factors. Globally, the distribution and management of urban green spaces are often inequitable (60, 61), with affluent neighborhoods typically having greater access to public parks and woody vegetation (62, 63). This disparity leaves lower-income, disadvantaged, and ethnic minority groups with limited green space access and minimal participation in urban forestry decision-making (61, 64). Consequently, in environmentally disadvantaged areas, low-income individuals are more inclined to opt for active travel for short distances, whereas high-income individuals in similar areas are less likely to do so (65).
The influence of street greenery on active travel is nuanced and varies across demographic factors such as age and gender. Studies targeting older adults and college students indicate divergent travel preferences, with older adults favoring quieter routes to destinations like supermarkets and restaurants (66, 67), while college students predominantly navigate within college campuses, relying on walking or bicycling due to limited public transportation options (45, 68). Notably, a gender disparity exists, with a lower percentage of older adult females engaging in cycling, attributed to perceived health limitations and security concerns (67, 69, 70). Understanding these demographic-specific factors is crucial for tailoring street greenery strategies to meet the diverse preferences of different age groups and genders. In addition to demographic factors, street greenery’s impact on active travel behavior is associated with economic income. Positive correlations are observed between street greenery distribution and housing prices, as well as street network density. Conversely, a negative correlation exists between street greenery and the proportion of socially vulnerable populations (71). Low-income individuals in environmentally disadvantaged areas are more inclined toward active transportation, while high-income individuals in environmentally affluent areas demonstrate a lower propensity for active travel (65), potentially linked to the spatial distribution of green spaces and higher rates of private vehicle ownership among wealthier households (72, 73). Furthermore, a negative association between household income and total walking time suggests that individuals with higher incomes exhibit a decreased likelihood of walking compared to their low-income counterparts (36, 40, 46, 49). Comprehensive evidence gathering is imperative to further explore how street greenery interacts with socioeconomic factors, influencing active travel behavior across various economic strata.
As highlighted in the 2021 Vienna Declaration and the Pan-European Master Plan on Cycling endorsed by the United Nations, active travel significantly impacts public health, necessitating innovative approaches to develop transportation and mobility systems that are clean, safe, healthy, and inclusive, aiming to reduce overreliance on the automobiles. This review provides valuable insights for urban planners, guiding street greenery initiatives. In the initial phases of urban street greenery planning, a thorough understanding of local demographics, including age, gender, and daily travel patterns, is essential. Categorizing roads based on their functions, such as accommodating traffic or serving recreational purpose, allows for the implementation of diverse buffer distances and specific street greenery features aligned with these needs. Policymakers and urban planners should concurrently prioritize enhancing the esthetics, comfort, quality, and safety of green spaces at eye level. Initiatives addressing air quality, road noise reduction, and design of multi-functional green spaces that foster social support are crucial. By creating an appealing environment, street greenery initiatives can enhance residents’ active travel experiences. Encouraging active travel behavior can be achieved through thoughtful and targeted urban planning strategies.
There are several limitations that warrant further improvement. Firstly, all included studies used an observational research design, posing challenges in establishing causal relationships. The lack of an experimental design prevents us from determining whether street greenery directly influences active travel or whether other factors may play a role. Therefore, future research could explore more experimental studies to better understand the causal relationship between street greenery and active travel. Secondly, the 26 studies included in this review were cross-sectional, limiting our observation to short-term changes in the relationship between street greenery and active travel. To comprehensively understand this relationship, it is essential to conduct longitudinal studies, providing additional insights into the dynamics over time. Furthermore, the exploration of intermediary mechanism through which street greenery affects active travel has remained predominantly theoretical, lacking empirical data analysis support. To address this gap, future research should focus on empirical data collection to delve into the intermediary mechanism. Conducting empirical studies will enable a more precise understanding of how street greenery influences active travel, offering valuable insights for urban planning and policymaking. By gathering empirical evidence, researchers can facilitate the development of supportive policies and strategies to create green street environments that are both friendly and comfortable, fostering active travel behavior.
5 Conclusion
This study provides a comprehensive and systematic review of the scientific evidence on the influence of street greenery on active travel, affirming its positive impact. However, the extent of this influence varies with factors such as temporal factors (weekdays vs. weekends), demographic segments (age and gender), proximity parameters (buffer distances), and green space quantification techniques. Street greenness promotes active travel by enhancing environmental esthetics, safety, and comfort, while also improving air quality, reducing noise, and fostering social interactions. In addition, the study suggests that variables like weather, seasonality, and cultural context may also correlate with the effectiveness of street greenery in encouraging active travel. To gain deeper insights into these complex relationships, future research should pivot toward experimental and longitudinal methodologies. Empirical analyses focusing on the intermediary mechanisms and contextual factors influencing the impact of street greenery on active travel are recommended. Such research approaches can elucidate the multifaceted dynamics of street greenness and its role in shaping active travel behavior more comprehensively.
Data availability statement
The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.
Author contributions
JY: Investigation, Writing – original draft, Software, Supervision, Validation, Writing – review & editing. HZ: Supervision, Writing – review & editing, Investigation, Validation. XD: Writing – review & editing, Supervision. JS: Writing – original draft, Writing – review & editing, Data curation, Funding acquisition, Investigation, Resources, Supervision.
Funding
The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by the Ministry of Education of Humanities and Social Science project, grant number 22YJC890024.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
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Keywords: street greenery, green space, walking, bicycling, active travel, review
Citation: Yu J, Zhang H, Dong X and Shen J (2024) The impact of street greenery on active travel: a narrative systematic review. Front. Public Health. 12:1337804. doi: 10.3389/fpubh.2024.1337804
Edited by:
Yuan Li, Shaanxi Normal University, ChinaReviewed by:
Thomas Bias, West Virginia University, United StatesMasoume Taherian, Ahvaz Jundishapur University of Medical Sciences, Iran
Copyright © 2024 Yu, Zhang, Dong and Shen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Jing Shen, shenjing@cugb.edu.cn