1. Introduction
Since the Industrial Revolution, the swift expansion of mechanized forms of transportation, including cars, trains, and subways, has led to urban challenges such as traffic jams, air pollution, and energy shortages. With environmental concerns becoming more pressing, the urban development model heavily reliant on private vehicles is proving to be unsustainable. The consensus for advancing sustainable urban transportation comprises controlling the expansion of private vehicular traffic, enhancing public transportation systems, and encouraging green commuting practices among residents. Urban metro transit has become a crucial solution to mitigate traffic congestion in high-density urban areas. Walking, as a transportation option, plays a critical role not only as a primary means of interchange for metro transit but also in connecting various service offerings in metro transit station zones [
1]. However, the reality in China demonstrates that metro transit construction often stalls at the TOD planning phase, failing to fully capitalize on the “walking advantages” in station areas. The
2020 Annual Statistical and Analysis Report on Urban Metro Transit notes that China’s urban metro network extended to 7969.7 km in 2020, with the network’s size increasing annually. However, data from 2012 to 2020 reveal a decline in passenger density alongside the growth of the metro network’s reach. This indicates that urban metro systems should not merely focus on expansion but should prioritize enhancing the functionality and environment of existing stations through specific design improvements or urban rejuvenation projects, aiming for sustainable operation at each location [
2]. The current limitations in designing pedestrian-friendly spaces around metro transit stations are primarily evident in several key areas: (1) a lack of coordination between transportation planning and land use, leading to areas around stations that lack appeal; (2) a prioritization of expanding the urban transportation network without equal emphasis on optimizing land use in the vicinity of metro transit stations, indicating potential for better land use efficiency; (3) an oversight in developing a conducive built environment and managing pedestrian flow in metro transit station areas, which reduces residents’ inclination to walk; and (4) a lack of attention to how urban landscapes are visually perceived and the implementation of visual navigation systems for transfers at stations, which curtails the benefits of pedestrian movement in these areas. Therefore, it is of significant importance to develop pedestrian-friendly environments in metro transit station areas for enhancing the willingness of pedestrians to walk to public stations, increasing the utilization rate of metro transit, and responding to climate change.
TOD is an integrated approach to urban planning that combines transportation infrastructure with land use, enhancing urban efficiency and promoting sustainable urban development [
3,
4,
5,
6]. The primary goals of TOD include encouraging walking, boosting public transit ridership, reducing congestion, and yielding environmental benefits [
7,
8,
9,
10,
11]. This development strategy is widely implemented in urban planning and strategic development efforts around the globe [
12,
13,
14,
15]. Schlossberg highlights that understanding opportunities for pedestrian movement is a key component in assessing TOD projects [
16]. Estupiñán emphasizes the importance of defining pedestrian spaces around transit stations to support the use of public transportation [
17]. Jacobson [
18] and Vale [
19] argue that the walkability of communities surrounding transit stations is crucial to their success, as it facilitates convenient, safe, and direct access to transit nodes. This, in turn, encourages a greater use of transit stations and ensures that TOD residents have access to local amenities to meet their needs. King explores how the walkability of communities around transit stops can inform future TOD developments [
20]. Morency, after conducting scenario simulations for four different plans in the Montreal metropolitan area, found that TOD areas could reduce walking travel distances by 28% [
21]. Nasri studies the impact of the built environment on mode of transportation choice within the context of TOD, using discrete choice models and focusing on the built environment at the origin of trips [
22]. Given that trips in rail transit begin and end with walking, walkability is a significant concern in TOD communities.
Regarding the assessment studies of urban walkability or pedestrian environments, the field of research can be classified into three categories: the objective spatial environment, the subjective spatial experience, and comprehensive evaluations. From the objective environment perspective, Dill [
23], Marshall [
24], and Jones [
25] have explored the correlation between residents’ modes of transportation (i.e., cycling and walking) and the urban form. They emphasize the significant influence that the structural properties of the street network exert on road connectivity. Chinese researcher Lu has introduced the Walk Score system adopted in the United States, acknowledging its utility in demonstrating how the layout of everyday facilities can affect the walkability score of urban areas [
26]. Yin has connected the walk score with urban design spatial variables across streets through the application of computer vision, presenting a 3D analytical perspective on urban walkability evaluation [
27]. Peiravian [
28] and Mayne [
29] have simplified the evaluation process through developing a pedestrian environment index that incorporates indicators such as land use diversity, population density, commercial density, and intersection density. On the subjective evaluation front, Millstein [
30] and Kurka [
31] have shifted the focus from a broad analysis of street connectivity to the specific elements that may affect residents’ willingness to walk in the built environment. They have carried out a Microscale Audit of Pedestrian Streetscapes (MAPS) scoring evaluation from the pedestrian’s perspective. Gou, utilizing semantic differential (SD) analysis, has performed landscape perception evaluations of street spaces in Nanjing and Shanghai [
32]. Similar studies include those by Shatu, who, in the absence of direct data, referenced existing factors influencing pedestrian path choices and employed computer virtual environments to facilitate the assessment of street walkability [
33]. Evaluations of the objective spatial environment predominantly rely on quantitative analysis of urban spatial walkability, spatial morphological characteristics, and specific functional layouts. Subjective spatial experiences are derived from the pedestrian’s perspective, focusing on surveying and understanding residents’ preferences and satisfaction levels with the walking space, thereby summarizing relevant patterns to further inform spatial design. This approach represents a type of qualitative research; comprehensive evaluations bridge the gap between objective and subjective viewpoints, finalizing a weighted scoring following a holistic analysis.
Research in various regions, both in our own borders and globally, on the subject of pedestrian environments near metro transit stations, reveals a consensus: creating a walk-friendly atmosphere extends beyond merely ensuring accessible road networks to encourage walking. It also involves curating a rich variety of destinations in the spatial layout to maintain residents’ interest in walking. Scholars, including Yan [
34], Guo [
35], and Zhao [
36], are of the opinion that managing the pedestrian space around metro transit stations should prioritize aspects such as connectivity, safety, comfort, and the holistic design of public spaces. Through the lens of the Ningbo case, Bai illustrated how communities around urban metro transit stations can be forged with thoughtful pedestrian environment planning [
37]. Olaru’s research has validated that enhancing public transport access on a city-wide scale can broaden the scope of residents’ activities and lessen their dependence on personal vehicles. This strategy necessitates the aggregation of public amenities near stations in reasonable walking distances as part of land development initiatives [
38]. Jeffrey and other scholars assessed the potential for transit-oriented development (TOD) at various stations along the Melbourne train loop, employing 14 pedestrian-centric criteria throughout their study [
39]. Lamour emphasized the importance of considering public space quality (safety, comfort) in the walking experiences of those living near station areas for the successful implementation of TOD models [
40]. Strategies to encourage walking among residents include diversifying land use types, introducing street-level commercial ventures, and interspersing small open areas (such as plazas and green spaces) along walkways. The inclusion of leisure amenities also plays a crucial role in making walking an attractive option for residents.
A comprehensive review of the existing literature identifies a limited scope of research focused specifically on evaluating pedestrian environments in these areas. Existing studies either lack granularity by focusing on the broader impact of TOD or utilize limited evaluation indicators that fail to reflect the full complexity of pedestrian experiences. Moreover, there appear to be insufficient systematic summaries of improvement strategies and empirical research on walking environments in Chinese metro transit systems. To address this gap, this study undertakes a quantitative comparative analysis of five metro transit station areas in Chongqing, China. The analysis focuses on three key dimensions: “comprehensive evaluation”, “basic scale”, and “structural quality”. The comprehensive evaluation considered factors such as the pedestrian catchment area ratio, POI kernel density distribution, and crowd agglomeration. The basic scale dimension comprised floor area ratio, building density, pedestrian road density, and the quantity of station entrances and exits. Finally, structural quality factors included land use type mixing degree, POI function mixing degree, intersection connectivity, median street length, pedestrian route directness, and green view index. By analyzing the shared spatial characteristics of these station areas and uncovering the linear relationships between relevant environmental variables, this study proposes optimization strategies for pedestrian-focused design in such situations. These findings can inform future planning efforts aimed at creating more walkable and accessible environments around metro transit stations, thus promoting sustainable transportation practices.
3. Factors and Quantitative Methods for Evaluating the Impact of Pedestrian Environment
The focus of this article is on exploring the factors that shape the pedestrian environment near metro transit stations, specifically through the lens of the physical layout encountered by residents during their commute to metro transit hubs or central areas. The objective is to identify ways to enhance travel conditions and motivate residents to opt for walking by adjusting key planning and design parameters. The key issue of our discussion is the “3D” principle of TOD, encapsulating Density, Diversity, and Design [
48,
49,
50]. This study further evaluates identifying factors that affect the pedestrian surroundings near metro transit stations, aiming to support pedestrian activities. These factors include walking opportunities, purposes, walkability, and the overall walking experience, grouped under comprehensive evaluation, basic scale, and structural quality indicators [
51,
52] (
Table 1). Through comprehensive evaluation, we seek to reflect the differences in phenomena caused by the development of land and traffic organization in different station areas. The basic scale indicator serves to measure the development prospects of a metro station’s surrounding area, while the structural quality indicator seeks to unravel potential challenges.
Comprehensive evaluation indicators offer a preliminary evaluation of the effects on development of metro transit station areas, thereby reflecting the holistic efficacy of the pedestrian environment and identifying areas with suboptimal pedestrian flow related to the walking environment. Comprehensive evaluation factors are operationalized through three indicators: pedestrian catchment area ratio, POI kernel density distribution, and crowd gathering.
On a fundamental level, basic scale indicators offer a preliminary judgment of the relationship between land utilization and transportation systems in the vicinity of metro transit stations. The presence of a robust population and comprehensive transportation services is key to optimizing pedestrian flow. Through an analysis of these basic scale indicators, it is possible to conduct a comparative analysis across different metro transit stations. Included in these indicators are the floor area ratio, building density, pedestrian road density, and the quantity of entrances and exits at metro transit stations.
Comprehensive evaluation factors offer a broad analysis of various differential phenomena, while indicators of structural quality shed light on the specific differences arising from land development and the organization of transportation systems. These structural quality indicators are instrumental in identifying limitations in the design of pedestrian environments around metro transit station areas. They consist of six key indicators: land use type mixing degree, POI function mixing degree, intersection connectivity, median street length, pedestrian straightness coefficient, and green view rate. The pedestrian environmental impact factors and calculations for the metro station area are shown in
Table 1.
5. Chongqing Metro Transit Station Walking Environment Optimization Study
5.1. Design Strategies for Metro Transit Station Walking Environment
This study argues that the determinants of the pedestrian environment in metro station zones can be categorized into three categories: comprehensive evaluation, basic scale, and structural quality. Nonetheless, each factor is integral to the broader frameworks of land use and transportation. Metro station areas optimized for pedestrian access should exhibit certain spatial organizational traits, and identifying these characteristics can lead to effective design approaches for enhancing the pedestrian experience in these areas.
In terms of the land system: (1) Implement compact development in metro station areas to ensure functional mix and diversity. This approach, characterized by high density and intensity, shortens distances between functions and increases the number of potential metro transit users and pedestrians in walking distance. In addition, each metro station should emphasize land-use compatibility. (2) In station core areas, attractive public centers should be created. Such centers highlight the advantages of pedestrian traffic and strengthen the connection between pedestrian behavior and urban space. This convergence of activity and transportation hubs offers mutually beneficial growth potential. (3) To ensure accessibility and maintain the integrity of pedestrian catchment areas and potential paths, large-scale functions and projects should be positioned with specific requirements on the outskirts of the stations, but in acceptable walking distances. The nature of these developments—including large land areas, closed management, and potentially poor land compatibility—can disrupt pedestrian pathways. (4) The advantages of walking by restricting private motorized traffic in core station areas should be emphasized. Metro station TOD should prioritize pedestrian traffic. Limiting private vehicles highlights the benefits of walking, reinforces positive pedestrian attitudes, and encourages potential pedestrians to embrace walking.
In terms of the transportation system: (1) Increase the density of pedestrian walkways to enhance the network of pedestrian paths, thereby reducing their dependency on roads designated for motor vehicles. Pedestrian routes offer the advantage of flexibility, allowing them to exist independently of vehicular lanes. By combing urban streets, alleys, and adjacent structures to incorporate pedestrian facilities, transform building sites, and carry out other design measures, it is possible to significantly increase the network of walkways near metro stations. This approach will lead to a comprehensive pedestrian path network, improving the connectivity of the road system. (2) In the core areas of stations, where the intermingling of pedestrian and vehicle traffic is especially significant, introducing traffic calming strategies is necessary. This can be achieved by directing traffic flow away from these congested zones using permeable transportation options, realigning roads to naturally reduce vehicle speed, creating separate paths for pedestrians and vehicles through underpasses, and designing traffic plans that favor pedestrian movement. Such measures aim to balance the needs of pedestrian and private vehicle traffic around metro stations, without entirely excluding the latter. (3) Promote pedestrianization in metro station areas, categorize road types and align them in a manner that favors pedestrian access in metro station vicinities. This involves a detailed analysis of urban road designations, construction methodologies, and the utilization of land adjacent to these roads. The objective is to distinguish between main roads utilized for traffic and local roads that serve the daily needs of residents, assigning them appropriate importance. Main roads should be relocated to the periphery, while local roads should be situated in the core station area, either parallel to each other or in a circular layout. This strategy focuses on road design with a priority on pedestrian movements in and around metro station zones. (4) Development of a multilevel pedestrian transit system: Enhancing the efficiency of pedestrian movement necessitates the creation of a three-dimensional transportation network. The traditional, flat-plane approach to traffic movement can be inefficient and disorienting for pedestrians. A multilevel system offers varied path options across different planes and elevations, integrating with surrounding buildings to minimize travel distances.
5.2. Strategies for Optimizing Pedestrian Environments at Various Orbital Station Sites
The areas to the north and south of Shapingba Station face spatial constraints due to the campus’s enclosed management, while the extensive centralized greenery of Shaping Park, located on the station’s southwest side, adversely affects the station area’s overall land use efficiency. Moreover, the high volume of traffic and volume of motor vehicles on nearby roads create human-made barriers, which restrict pedestrian movement. To address these challenges, we recommend the following optimization strategies: (1) To alleviate spatial compression, it is advisable to remove walls to extend the campus boundaries, thereby facilitating temporary pathways. This approach aims to mitigate the tension between land usage and transportation demands. By directing the flow of passengers to utilize internal roads during peak commuting times and holidays, we can offer a greater variety of routes and thereby broaden the accessible area around the metro station. (2) By reimagining centralized green areas, transitioning them from broad expanses to linear shapes, and eventually to focal points, we can boost land utilization. It is essential to promptly integrate underutilized parcels in the station’s vicinity into urban regeneration initiatives. This includes the creation, renovation, and enlargement of urban green spaces, such as street-side greenery, mini-parks, and green corridors, enhancing the living environment. Such measures should also aim to coordinate the spatial relationships between various land uses and the station. (3) To overcome the limitations imposed by artificial barriers, introducing vertical spatial integration and establishing access points that cross these barriers, is recommended. This involves separating pedestrian and vehicle traffic vertically in the traffic management design and constructing station entrances and exits to improve pedestrian transfer convenience.
The volume rate and the construction density at Ranjiaba Station rank as the lowest when compared to four other stations, and its geometric layout combined with the organization of factors does not favor the establishment of a TOD area in the vicinity of the metro station. The variety of POI functions at Ranjiaba Station is considered moderate, yet it has the smallest number of POIs among the stations in question. The areas surrounding the station predominantly consist of residential zones and government buildings, featuring uniform primary functions and enclosed spatial development patterns for each block, which restricts pedestrian access to city services. The layout of the streets and pathways at Ranjiaba Station results in a scattered arrangement of POIs, exhibiting less concentrated POI clusters compared to other nearby regions. In light of these challenges, we propose the following strategies for enhancement: (1) Adopt a compact development approach to address the issues related to the low density and intensity of development. This can be achieved by setting minimum thresholds for building density and volume rate through rigorous planning controls, thereby fostering a balance between environmental quality and the efficient use of space. Adjusting the share of land designated for roads and encouraging the creation of open spaces in blocks will support the desired high-density and vibrant spatial characteristics specific to the metro station area. (2) Introduce a variety of factors to cultivate appealing public areas near the station. (3) Restructure the distribution of road access to facilitate the development of pedestrian zones in the metro station area. This involves prioritizing pedestrian mobility services and imposing limitations on private vehicle traffic, with the aim of enhancing and protecting the community’s preference for walking as a mode of transport.
The quantified results from Guanyinqiao Station exhibit that, while several aspects are excellent, the connection between intersection buffering zones and PCA is notably weak. The landscape in the station’s vicinity features varying elevations, with roads that are both straight and winding, alongside the presence of cul-de-sacs in certain sections. Among the five stations analyzed, Guanyinqiao Station scored the lowest on the VGI, highlighting a less than ideal pedestrian experience. To enhance the walkability around the station, it is crucial to address the issue of cul-de-sacs by integrating them into a more comprehensive pedestrian network. Improving the design of street landscapes could also play a significant role in rendering longer walks more appealing, thereby encouraging greater participation in walking as a viable mode of transport.
With respect to Daping Station, it is observed that its connectivity as a transit hub surpasses its commercial appeal, and it displays a rather dense development pattern. However, in its vicinity, there exist underdeveloped plots such as aged residential blocks, governmental bodies, and public enterprises. Moreover, the 1000 m PRD assessment points out that Daping Station experiences the most significant detours for pedestrians among the stations studied. To foster a better walking environment around the station, it is necessary to promptly redevelop underutilized lands to boost land use efficiency, albeit in a constrained scope. Embracing high-density urban layouts where feasible will elevate the overall density of the station area. Concurrently, enhancing the pedestrian network by increasing the density of walkways and broadening their reach is essential for rendering the area more accessible and walk-friendly.
The residential land use of Nanping Station is excessively concentrated, paired with a significant lack of diversity in both land utilization and the functions of POIs. Constructed in the mountainous terrain, Nanping Station contends with significant elevation differences, complicating the creation of efficient spatial connections with the nearby buildings. This situation adversely affects the walkability and convenience for pedestrians, particularly in navigating transfers. Moreover, an analysis with the 400 m PRD metric reveals a pronounced tendency for circuitous routes around Nanping Station. To address these challenges, we propose several optimization strategies aimed at enhancing the area’s functionality and accessibility: (1) promoting land use adjustment and improving the diversity of metro station domain. (2) In consideration of the significant elevation difference, a three-dimensional walking system to be established for walking efficiency enhancement in different directions and spatial levels is required. (3) Optimize the 400 m core circle layer road network to improve detours and highlight the advantages of walking. In addition to increasing pedestrian road density, attention should also be paid to the layout of surrounding land use. Encouraging non-residential functions in the core vicinity as well as establishing compatible land use policies can ensure that the area remains open and accessible, free from constraints of spatial ownership. Moreover, managing the dimensions of streets and land parcels can help in developing a compact, densely built environment that supports a pedestrian-oriented metro station area, through joint land and transport planning efforts. (4) The connection between the station entrances and exits as well as the walking system can be strengthened to facilitate residents’ walking transfers.
6. Conclusions
While metro transit demonstrably alleviates traffic congestion and improves the climate in densely populated urban areas, the pedestrian environment surrounding stations is often neglected during construction, hindering the full potential of walkability. This study addresses this critical gap by proposing pedestrian-focused improvement strategies, not only to enhance the walking experience in metro transit station areas but also to cultivate more human-centric and sustainable urban spaces. Optimizing the pedestrian environment in the station domain can increase the appeal of public transportation, encouraging a modal shift toward metro transit and promoting low-carbon walking habits. This transformation is expected to effectively reduce greenhouse gas emissions from the transportation sector, thereby addressing the challenge of climate change, and contributing meaningfully to the realization of sustainable urban development.
This article evaluates five metro transit stations in Chongqing as case studies and categorizes the factors influencing the environmental aspects of metro station zones into three groups: “comprehensive assessment”, “basic scale”, and “structural quality”. It employs a mix of quantitative and qualitative analyses to explore the relationship between various factors, facilitating a comparative review across different stations. Based on these analyses, this study proposes a series of pedestrian environment design strategies including land use and transportation. The strategies for land use advocate for “developing compact and diverse land use”, “strengthening attraction of station center”, “positioning large projects on the edge”, “restricting private transportation capabilities”. The strategies for transportation consist of “increasing pedestrian road density”, “traffic calming organization”, “subdivision of road types”, and “three-dimensional pedestrian traffic system”. This article concludes by identifying the challenges faced by the five stations and suggests improvement measures for pedestrian spaces at each location.
This paper carries out an objective evaluation of the metro transit station environment through quantitative analysis of key performance indicators and by informing optimization strategies for pedestrian flow and experience. Nonetheless, two limitations remain in this research: (1) The methodological approach lacks qualitative insights collected from pedestrian interviews. Future research should integrate quantitative and qualitative methodologies for a holistic evaluation. (2) The current indicators neglect the effect of weather conditions on pedestrian behavior. Further analysis is required to optimize and assess pedestrian-centric design solutions in extreme temperatures.