Reimagining the High-Density, Vertical 15-Minute City

Abstract

In recent years, the 15-minute city (15MC) model has gained significant attention among scholars and practitioners, particularly in the wake of COVID-19. However, limited research has explored how this model can be adapted to high-density, high-rise urban environments characterized by compact land use and mobility challenges. This study addresses this gap by extending the core principles of the 15MC—density, proximity, diversity, and digitalization—with additional context-specific dimensions: mobility choice, walkability and cyclability, public transport proximity, inclusivity, placemaking, and policy integration. Using qualitative research and site observations, we analyze three diverse neighborhoods in Singapore: Clementi, Toa Payoh, and Holland Village. The comparative evaluation reveals the strengths and limitations of applying a vertical, hierarchical, and multilayered planning model in dense urban contexts. The study also highlights the potential of a three-dimensional planning framework that integrates vertical and horizontal spatial structures to optimize accessibility and functionality. The findings contribute to the broader discourse on sustainable urbanism by offering actionable strategies to support the transition toward more accessible, low-carbon, and livable high-density cities.

1. Introduction

1.1. Background

Politics, pandemics, climate, and advancements in technology have always influenced and triggered changes in the way cities are planned and perceived. While the industrial revolution and access to automobiles stretched our cities, dividing them into monofunctional zones that relied on cars and public transport to reach work and daily needs, the recent pandemic COVID-19 highlighted the value of polycentricity with distributed services that enable easy access to daily needs, open green spaces, social infrastructure and community facilities. The health crisis reestablished the significance of the “mixed use” as people relied on their homes for work/play and on services and daily needs in the vicinity of their homes [1].

The planning of services impacted social distancing which was seen as key to fighting the pandemic from not spreading from one community to another [2]. The disruption caused by the pandemic has made us think of new ways to create livable and human-centric neighborhoods. The 15-minute City is one such model relying more on walking and cycling for daily needs, enabling meeting fellow residents in safe urban environments and providing access to social and cultural infrastructure [3].

1.2. Objectives and Methodology

This research examines the definition, evolution, and development of the 15-minute City, and identifies the principles (density, proximity, diversity, digitalization, inclusivity), strategies, and framework through a literature review and case studies [4]. Case studies (Barcelona, Singapore, Melbourne) are used to identify salient features and spatial forms of the 15-Minute City that have led to reflections on standards of scale and density for 15-minute neighborhoods [5].

Learning from the existing 15-minute cities, the aim of this research is to propose an adaptable 15-minute framework for high-density contexts and recommend the principles, scale, and form to help transform existing neighborhoods to adapt to more green and sustainable modes of mobility, i.e., walking and cycling. The 15-minute city model fundamentally rethinks urban life by ensuring that essential daily services—such as healthcare, groceries, schools, and recreation—are reachable within a short walking or cycling radius, thereby minimizing dependence on private vehicles, cutting emissions, and promoting healthier lifestyles. Its emphasis on accessibility also benefits diverse populations, including the elderly and those with limited mobility, by encouraging barrier-free pathways and community-scale planning. The resulting hyperlocal networks foster social interaction and can mitigate disruptions caused by crises such as pandemics or fuel shortages, as neighborhoods remain resilient and self-sufficient. Ultimately, its people-centered, time-based approach reorganizes land use and mobility so that urban living is more equitable, sustainable, and community-focused, particularly crucial for high-density cities where land is constrained and resident needs are diverse.

To understand the planning and complexity of existing environments, three different neighborhoods in Singapore are selected—Clementi North, Toa Payoh Centre, and Holland village. In particular, Clementi North is predominantly residential and seamlessly linked to transit nodes, reflecting the classic layout of Singapore’s mature housing estates; Toa Payoh Centre, known for its barrier-free design and diverse amenities, exemplifies an inclusive, well-established community; and Holland Village features lower-density housing adjacent to business parks that offer local employment, making it emblematic of a mixed-use neighborhood. These three examples collectively represent a cross-section of Singapore’s common urban typologies, providing a robust foundation for analyzing different high-density contexts in Section 4. More specifically, the research sought to delineate the study area and examine the distribution of facilities, facility type, hierarchy and numbers, to assess if they met the 15-minute neighborhood criteria. The objective was to assess their current performance and to propose relevant mobility and urban design strategies to transform them into 15-minute neighborhoods.

With a city formed of several, varied neighborhoods, “overlapping zones” of walking and cycling catchments, where different neighborhoods have access to common, often larger amenities, are also proposed. Furthermore, vertical planning of amenities to improve land use efficiency, connectivity, and mobility, particularly in the high-rise, high-density contexts, is also explored. It leads to the exploration of new urban forms for a vertical “hyperconnected” city.

2. Overview of 15-Minute City

2.1. Historical Development of Cities

City planning has always explored new ways of bringing people closer to services using transport means. In the Medieval City (700s–1400s), different city functions were more intermixed and confined within the city walls, and reached easily by walking through well-connected, organic streets [6]. The Industrial Revolution (1760s–1830s) and the advent of mass production not only revolutionized manufacturing methods but also physically separated industrial activities from residential areas, effectively contributing to the spatial division of work and home [7]. With the invention of the car, there was an acceptance of traveling long distances between home, office, shopping, and homes, with zoning and suburbia gaining prominence (See Figure 1). Ebenezer Howard’s Garden City (1898) proposed the creation of compact suburban towns near nature with basic services [8].

Clarence Perry’s Neighborhood Units (1926) focused on the neighborhood scale to create compact, walkable residential areas with proximity to services, especially green and social infrastructure contributing to the creation of safe and vibrant communities [9]. Harris and Ullman’s polycentric city (1945) argued the need for multiple growth centers within cities and self-sufficiency of the different centers in terms of employment and services [10].

Transit Oriented Development (TOD) is an urban planning approach that emphasizes compact, mixed-use development near major transit nodes, thereby reducing reliance on private vehicles and promoting walkable, sustainable communities. By situating housing, offices, retail, and other services within easy reach of reliable public transport, TOD has effectively reintroduced density as a key driving principle for planning cities and providing widespread access to essential amenities [11]. Hägerstrand’s Time Geography, which then evolved into Chrono Urbanism (1997) envisioned multiple uses for one place to offer more flexibility, according to the time of day [12]. Driving flexible and multi-use planning rooted in policies through questions like: What if we turned roads into parking lots at night? What if educational spaces became shelters at night? [13].

2.2. Implementation of the 15-Minute City in Global Cities

Historical shifts in urban planning—from organically integrated medieval cities, through car-dependent suburban sprawl of the industrial age, towards contemporary models emphasizing compactness and connectivity—highlight a fundamental evolution in how cities address accessibility and quality of life. The historical principles of mixed-use proximity, polycentricity, and dense neighborhood units now underpin modern urban strategies. These planning models laid the groundwork for later proximity-based concepts. While the 15-minute city has gained significant attention in recent years, its conceptual foundations are deeply rooted in earlier urban design theories that emphasized compactness, walkability, and human-scale development. Notably, Leon Krier was among the earliest critics of modernist zoning and suburban sprawl, advocating instead for traditional urban forms characterized by mixed uses, short distances, and coherent architectural language. His vision of the “city as an integrated whole” and emphasis on walkable blocks, central squares, and civic buildings remains influential in contemporary planning discourse [14]. Similarly, Andrés Duany and Elizabeth Plater-Zyberk, co-founders of DPZ CoDesign and leading figures in the New Urbanism movement, translated many of Krier’s theoretical propositions into practical urban design models. Their work on communities like Seaside, Florida [15] and the formulation of the Charter of the New Urbanism (1996) promoted neighborhood structures organized around a five-min walk, with interconnected streets, a mix of housing types, and active public spaces. Today, many cities globally integrate these evolved principles, adapting them according to their unique geographic and socio-economic contexts. Singapore, in particular, exemplifies this integration by effectively synthesizing historical insights with innovative spatial planning approaches tailored specifically to its limited land resources and high-density urban form.

Influenced by past concepts, Moreno’s 30-minute territory and 15-minute city concepts advocate a lifestyle change with a focus on walking and cycling to reach daily amenities [16]. They emphasize cutting emissions from engines and developing more sustainable, human-scale, vibrant neighborhoods with all services accessible by foot or bike within 15 min. The 15-minute city model stresses time-based planning for easy access to living, work, shopping, healthcare, education, and leisure.

Since then, many cities have adopted this model including Paris (2020), Barcelona, and Milano (2020) creating more inclusive, safer, and vibrant communities with improved walking/cycling networks, access to daily services through policy, and flexible mixed-use planning. In Paris, the city converted the Seine riverbank from a highway previously used by over 40,000 vehicles daily into a car-free linear park and bike-friendly infrastructure, significantly reducing air pollution and improving urban livability. This transformation created over 1000 km of cycling routes city-wide [17]. In Barcelona, implementing the “superblock” concept in Poblenou resulted in a 31% increase in street-level commercial establishments, boosting local economic vitality [18]. Similarly, Milan upgraded its streetscapes through a sustainable urban mobility plan, lowering speed limits to 30 km/h on 60% of the roads, significantly enhancing pedestrian safety and encouraging active mobility [18]. Portland’s “20-Minute Neighborhoods” strategy also sets measurable targets, aiming for 80% of residents to easily access daily necessities by foot or bike by 2030, with targeted improvements prioritized in underserved communities [19]. Singapore, given its scale and a City-State status, envisions 20-minute towns and a 45-minute city where amenities such as schools, shops, and parks will be reached easily by walking, cycling, or public transport [20]. The 15-minute city planning framework was proposed by Cleveland in 2022 to rebalance neighborhoods with spatial proximity to essential services within a 15-minute walk, bike ride, or transit trip, and with economic proximity by bringing jobs, services, and infrastructure closer to residents. Buenos Aires, which measured “the success of a modern city by going faster and further”, adopted a proximity-based urban transformation model that transformed roads into “green streets” with slow mobility and an inclusive urban environment with a “city close to home“ as part of their Climate Action Plan 2050. Sousse’s 15-minute city is using “Chrono-urbanism”, “Chronotopy” and “Isochrones” to plan public facilities within a 15-minute walking or cycling radius as part of their Integrated Urban Development program. Busan, in the Republic of Korea, is also embracing the 15-minute city vision based on “happy proximity” focused on introducing comfortable living facilities accessible by walking to promote its transition towards a carbon-neutral city. Many small towns and villages across Scotland and France are also inspired by the concepts of “happy proximity” to introduce national planning programs for reviving villages and revitalizing Scotland through 20-minute territories [16].

Most of the current models focus primarily on proximity-based planning with amenities that can be reached by walking and cycling distances under the 10, 15, 20 min time frame. However, the framework for implementation can be further refined to suit different densities to meet the demand and to provide access to different scales/types of amenities whilst avoiding the risk of their oversupply.

The 15-minute city represents an urban model in which the essential needs of residents are accessible on foot or by bicycle within a short perimeter in high-density areas. Similarly, the 30-minute territory extends this concept to less densely populated areas where commutes can take a little longer [16]. The framework may also be adapted to create new city planning ideologies. Therefore, this research proposes a new framework that aims to further define the distribution of amenities appropriate for different scales, and to explore the potential of overlapping areas for spatial planning purposes, in the context of high-density cities.

2.3. Transport and Mobility Within a 15-Minute City

The concept of a “15-minute city” prioritizes walking and cycling for the residents of an urban community to satisfy most of their daily needs, such as food, clothing, housing, transport, education, and recreation. Walking and cycling can also be expanded to include personal mobility devices such as e-scooters, e-bike, etc., as technology evolves (see Figure 2 and Figure 3).

Improved choice of mobility within the neighborhood helps to improve access to services. However, it is important to recognize that different modes of transport operate at different speeds and have a huge impact on the time taken to reach the different services. A cyclist or electric vehicle user would cover a substantial 15 min radius distance compared to those on foot. Moreover, universal design for improved access for all ages and people with impaired or reduced mobility is also necessary.

2.3.1. Multimodal Catchments: Active Transport and Public Transit Modes

Figure 2 makes this envelope tangible. Concentric rings (400 m, 800 m, 1200 m) illustrate the territory an average pedestrian can reach in 5, 10, and 15 min. Radial arrows overlay speeds for other modes:

• Slow walking/assistive devices (≈1 km h⁻¹) extend the 15-minute catchment to ~250 m, highlighting the importance of barrier-free design for the very young, elderly, or mobility-impaired.
• Typical walking (3.5–5 km h⁻¹) expands the radius to 1.0–1.2 km.
• Cycling and e-bikes (15–25 km h⁻¹) push the reachable area out to 3.7–5 km.
• Neighborhood buses or LRT (25–40 km h⁻¹) stretch the 15-minute horizon to 6–10 km, effectively linking multiple 15-minute neighborhoods.

2.3.2. Recommended Mobility Systems Within 15-Minute City

Figure 3 translates these catchments into a recommended mobility hierarchy: walking and cycling proximity helps to improve last-mile connectivity to public transit as well. Fast-moving public transit, such as buses, Mass Rail Transit (MRT). and trains, which improve connectivity across neighborhoods, are also included in some models of 20 and 45-minute cities and 30-minute territories.

3. Methodology: Making 15-Minute Cities

In our study, we primarily employed two methodologies: site observations and desktop studies. Site observations were conducted across various neighborhoods in Singapore to directly assess urban elements such as infrastructure, pedestrian flow, and the availability of services. This hands-on approach allowed us to gather real-time, qualitative data on the spatial dynamics and usability of urban spaces.

Additionally, we complemented our field observations with desktop studies, which involved a comprehensive review of the existing literature, urban plans, and publicly available data. This method enabled us to contextualize our observations within broader urban planning theories and historical data.

To enhance the clarity and coherence of our methodological approach, we developed a graphical research framework (Figure 4) that illustrates the structure and key components of the methodology adopted in this study. This framework synthesizes the guiding principles, spatial scales, and demand hierarchies of the 15-minute city model while also mapping out how these theoretical constructs were examined through case studies and subsequently evaluated. By visually structuring the research process, the framework helps to explain the logic behind our selection of methods, the layered nature of spatial analysis, and how findings were derived and assessed across different scales and urban contexts. It serves as a conceptual anchor for understanding how our research moved from foundational concepts to context-specific application and critical evaluation.

3.1. The Key Principles of 15-Minute Cities

3.1.1. Essential Principles in 15-Minute City Frameworks

A review of existing 15-minute city research reveals four foundational principles—density, proximity, diversity, and digitalization—that guide the creation of accessible, mixed-use urban environments [22,23]:

• Density

Density focuses on creating compact, vibrant areas with well-developed services and facilities.

2.

Proximity

Proximity emphasizes designing walkable or bikeable neighborhoods, so people can reach services within a short time and without depending on private vehicles.

3.

Diversity

Diversity ensures a mix of land uses—residential, commercial, recreational—and also acknowledges cultural variety and bottom-up community participation.

4.

Digitalization

Digitalization draws on “Smart Cities” and the “Internet of Things” to facilitate innovative services—such as bike-sharing programs and digital platforms—for more efficient 15-minute neighborhoods.

However, these established principles do not fully account for the unique challenges of high-density, vertical cities, namely, limited land availability, complex multi-level planning, and overlapping populations that can exacerbate socio-spatial inequalities. They also tend to underemphasize emerging mobility options (e.g., e-scooters, e-bikes) and inclusive, bottom-up participation, both of which are crucial in densely populated, multicultural environments.

3.1.2. Toward a New Scalable Framework for High-Density Cities

To address these gaps, we propose an expanded framework that retains the core 15-minute city principles while adding five additional considerations specifically tailored to vertical, high-density contexts:

• Choice of Mobility

Emphasizes different speeds and personal mobility devices (e.g., e-bikes, PMDs), enabling residents to cover greater distances within 15 min.

2.

Walk and Cyclability

Prioritizes pedestrian and cyclist safety through wide, well-connected pathways, improved road junction design, and secure bicycle parking.

3.

Proximity to Public Transport

Ensures robust, conveniently located transit nodes for city-level commuting.

4.

Inclusivity

Promotes barrier-free design and universal access for all ages and abilities, addressing equity in high-density areas.

5.

Placemaking

Encourages active community participation, comfort, and social cohesion within shared public spaces, whether at ground level or integrated vertically.

6.

Policy

Drives behavioral shifts (e.g., walking and cycling incentives) and accommodates flexible land uses, from multi-functional rooftops to shared school spaces after hours.

These newly emphasized elements help tackle the complexities of dense, vertical neighborhoods, including overlapping demands on infrastructure, the need for multi-level connectivity, and serving diverse populations within limited space. By strategically arranging amenities and encouraging efficient overlaps in activity zones, this expanded framework aims to keep everyday needs within a compact, human-centric radius—even in environments characterized by towering buildings and tight land constraints. In forming this expanded framework, we combined the four essential principles with six newly proposed ones, resulting in a set of ten guiding principles. The table below outlines these principles, along with additional explanations and, where relevant, practical illustrations (

Table 1. Key principles of 15-minute city.

	Proximity to essential services: Distribution of daily need and essential services within 15 min walking and cycling distance of all residents. This eliminates the need to travel far from home to access amenities/services, reducing traffic on the roads and increasing car-independent mobility within neighborhoods.
	Choice of mobility (new): Walking and cycling are considered as the key mode of transportation for the movement of people within the 15-minute city. Given the different speeds of the various modes of transport, one can cover a greater distance in 15 min by using faster means of active transportation, e.g., electric bike or e-scooter.
	Proximity to public transport (new): For the residents to access city-level amenities, services, and businesses, e.g., higher education, specialty hospitals, and offices planned outside the neighborhood without relying on a car. Local public transport may also be considered as an additional mode of transport, especially for people with reduced mobility. For example, significant enhancements to the transport infrastructure, including transit priority corridors and the continued expansion of the rail network, have been instrumental in encouraging more people to commute to work via public transport in Singapore [24].
	Walk and cyclability (new): The safety of pedestrians and cyclists is another important aspect. Wide, well-connected, unobstructed, and continuous walking and cycling pathways. Wider pedestrian crossings for safety through improved road junction design. Secure bicycle parking and storage arrangements. Well-shaded and sheltered areas ensuring comfort. Seating areas along pedestrian pathways for rest and meet and greet fellow residents that increase community engagement and improve the neighborhood’s sense of safety positively.
	Inclusivity (new): Universal design and mobility options for people with mobility impairments including the provision of wheelchairs and other mobility aids. For instance, the Land Transport Authority (LTA) in Singapore has implemented extensive barrier-free access across its public transport network. This includes allowing open strollers, wheelchairs, and other Personal Mobility Aids (PMAs) such as mobility scooters on buses and MRT/LRT trains [25].
	Density: The population and employment density of a neighborhood should be able to support the existence of local businesses, amenities, and services that are essential for a self-sufficient neighborhood. Medium-to-high-density neighborhoods could support vibrant mix of uses and amenities.
	Diversity and Flexibility: A variety of uses and amenities within the neighborhood fulfill daily needs of the residents. Transient uses can be planned to meet short-term or intermediate demand for amenities within a neighborhood.
	Placemaking (new): Creating public space and incorporating amenities through community participation and to support active community engagement. Improve comfort of residents for walking and cycling through improved urban design and streetscape design, enhancing residents’ quality of life and improving their physical and mental health.
	Digitalization and innovation: Integrate use of diverse and advanced technologies to collect and analyze data for demand-based planning of essential services. Technology and innovation to support access to remote services without adding traffic to the road, e.g., remote working, online shopping. On demand/mobile services, popup amenities to provide essential services at doorstep.
	Policy (new): It is key to incentivizing and bringing positive behavioral changes towards walking and cycling. Policies can facilitate flexible land and building use to allow for improved provision of and access to urban amenities and social infrastructure, e.g., school yards for public use after school hours and weekends, access to roof top green for community gardens, and adaptable street design to plan amenities within proximity of homes.

).

3.2. The Scale of 15-Minute Cities

We determined the scale of implementing the 15-minute city model by assessing various catchments or spatial proximities. These assessments were based on the average walking and cycling speeds and the time it took to access different amenities within the neighborhood (See

Table 2. Scales of 15 Minute City.

Scale		Challenges
Development Scale
	During the pandemic, our homes formed the place for multiple activities during different times of the day, e.g., daily living, work, exercise, and other recreation. Digital technology was used to access essential services leading to less traffic on the roads and improved air quality.	The key challenge is incorporating services at building/development scale
Precinct Scale
	Learning from the Barcelona City superblocks, 400 m × 400 m modules are created with inner-minor streets within the clusters bounded by arterial roads at the perimeter. The superblock scale is bigger than a regular city block (usually 100 m × 200 m) but smaller than a neighborhood (over 800 m). All essential amenities and community services are planned within the superblock and a 5 min walking distance (400 m). The safe “green” streets within the superblock help to improve walkability to access community facilities. The proximity of services and social infrastructure also improves community engagement.	All essential amenities and community services are planned within the superblock within a 5-min walking distance (400 m); risk of oversupply of amenities if the right densities are not met within the superblock.
The Neighborhood Scale
	Neighborhood scale was first defined in 1929 by Clarence Perry as a quarter-mile pedestrian shed [26]. Within the Singapore Planning context, a neighborhood unit (800 m × 800 m, 10 min walking distance) has around 4000 to 6000 dwelling units with their own neighborhood centers (NC) with shops, primary and secondary schools, and parks.	Limited consideration for elderly and people with reduced mobility

).

The focus of this study was to define the scale of a 15-minute city with active mobility (walking and cycling). A 1200 m × 1200 m walking radius at the neighborhood scale, which would be a maximum 15 min walking distance and 5 min cycling distance to access all community facilities and urban amenities from homes within a neighborhood, is recommended (Figure 5).

3.3. A Hierarchical Framework: 15-Minute City

The “flower of proximity” was based on María Teresa Baquero Larriva and Patxi Lamíquiz [27]. Six color-coded petals—education, healthcare, commerce, business, civic, and parks and sports—radiate from the household core, grouping everyday destinations by function. Inside every petal, three dashed isochrones mark what a resident can comfortably reach on foot in roughly 5, 10, and 15 min (Figure 6):

Five-min ring—essential, high-frequency needs.

Examples include kindergartens, playgrounds, pharmacies, convenience food outlets and ATMs. These facilities belong in the inner ring and should be located within residential areas so that children, older adults, and people with limited mobility can reach them without crossing busy roads.

Ten-min ring—weekly or routine destinations.

Secondary schools, neighborhood supermarkets, hawker centers, clinics, community centers, and local worship spaces sit here. These uses tolerate a slightly longer walk yet still depend on a safe, continuous pedestrian network.

Fifteen-min ring—occasional but still regular activities.

High schools, cinemas, small theatres, larger parks, and co-working hubs occupy the outer band, emphasizing that these mid-order amenities should remain comfortably reachable by walking or cycling even when they are shared across neighboring districts.

Expanding upon the principles of 15-minute cities proposed by previous scholars, we propose a new scalable framework suitable for high-density environments. This framework provides a recommended scale for a 15-minute neighborhood and, importantly, distributes amenities and mobility based on a 5, 10, and 15-minute hierarchy concept.

Precinct-level amenities should be within a 5 min walking distance (radius: 250 m–400 m), while neighborhood-level amenities should be accessible within 10 min (radius: 600 m–800 m) and up to 15 min (radius: 1000 m–1200 m) by walking. These facilities within precincts and neighborhoods are intended to meet most residents’ daily needs, thus minimizing the necessity of using cars for such trips.

Higher-order amenities can be strategically located between different neighborhoods, accessible via active mobility options and public transportation. Town-level amenities may be designed to be reachable within a 10-min cycling distance (radius: 1500 m–2 km), while city-level amenities should ideally be within a 15-minute cycling distance (radius: 3.75 km–5 km).

3.4. Form of the 15-Minute Neighborhood: The Spatial Model

We explored the different forms of 15-minute neighborhoods in both horizontal and vertical city layouts. The form also explored the “overlapping zones” of walking and cycling catchments for different neighborhoods to share different scales of amenities. This helps to manage the economy of scales and avoid the risk of oversupply of urban amenities within neighborhoods of different densities. Vertical cities with mixed use are also seen as another form of 15-minute neighborhood to plan urban amenities within 15 min proximity utilizing vertical transport to access these amenities at different levels. Specifically, it focuses on the vertical stacking of amenities in high-density cities, enabling people to reach required amenities faster within a compact area (

Table 3. The spatial model of 15-minute city.

Form	Distance	Services
	Five-min walk (250 m–400 m) from center to the edge—daily needs, a range of housing types, and some scale amenities are planned. Five-min walking vertical neighborhood using vertical transport; mixed use building to plan amenities for daily need.	Daily needs, a range of housing types, and a center (generally a public square or main street with minimal mixed use), small businesses.
	A 600–800 m walk from the center to the edge—housing types, daily amenities/essential services, and some neighborhood-level facilities. Utilizes vertical transport with 5 min walks to access connected buildings; mixed-use buildings are designed to include amenities for daily needs.	Range of housing type, daily amenities and essential services to cater to different demands, including some neighborhood-level facilities.
	A 15-minute walk should cover a distance of approximately 1000–1200 m. People can reach neighborhood amenities using vertical transport and then walk for 10 min to access connected buildings. Mixed-use buildings include amenities for daily needs-public and community centers, supermarkets, and local working opportunities, serving multiple neighborhoods.	General merchandise, public (primary) schools and community clubs, sports centers, small playgrounds to larger parks that serve multiple neighborhoods and local working opportunities.
	The 15-minute Spatial Model with overlapping zones for sharing amenities between different neighborhoods	Higher order amenities such as library, botanic garden, hospitals, universities, etc.
	15 min cycling shed with 15 min walk sheds within; 4800 m from center to edge	Major cultural, medical, and higher-education facilities, regional parks, major employers, access to intercity transit.

).

Unlike Singapore’s current pattern of transit-oriented developments—where MRT stations integrate with shopping malls, community centers, and bus interchanges in one central hub—our 15-minute Spatial Model proposes a multi-nodal distribution of amenities spread across 15-minute walking and cycling “petals”. By decentralizing facilities to multiple nodes, we address the gap often faced by residents on a neighborhood’s periphery, who might otherwise need to leave their immediate area to access daily essentials. Furthermore, our approach actively stacks multiple community services within mixed-use buildings, conserving valuable land in high-density contexts and enhancing connectivity through more efficient, multifunctional shared spaces.

4. Case Study—Applying the Framework to Three Singapore Neighborhoods

To test the feasibility of our model, three specific neighborhoods of Singapore (Bouna Vista and Holland Village, Clementi, and Toa Payoh) were examined to ascertain their existing conditions. The planning and distribution of urban amenities, facility type, hierarchy and numbers, and walking/cycling infrastructure were assessed to see if they met the 15-minute city criteria (

Table 4. Singapore’s three neighborhoods.

Descriptions	Part of Bouna Vista HDB and Holland Village	Clementi North and Central	Toa Payoh Central
Introduction	Holland Village offers diverse amenities and a low-density environment with private landed houses. The business parks in the area provide numerous job opportunities.	A high-density mature HDB town with easily accessible amenities, mixed-use buildings, combining commercial, residential, and public transit facilities. Amenities within the 15-minute neighborhood are easily accessible by walking or cycling.	A high-density, mature, inclusive and livable environment with barrier-free amenities, recreational facilities, and plenty of activities are held regularly.
Density (2020)/km2	10,906	18,000–23,878	25,305–28,000
Land use	Land use in Holland Village is predominantly residential, with some business areas.	Land use in Clementi is predominantly residential, with amenities comprehensively distributed within a 15 min walking radius.	Land use is mainly residential, with well-distributed amenities, including multiple children’s parks and retail shops for every need.
Distribution of Amenities	Most amenities are within a 15 min walk. Although essential services like food courts and markets are centrally located, due to the unequal distribution of amenities, it takes longer to reach them from some peripheral areas.	Most amenities and essential services are within a 15 min walk.	Good distribution of amenities, improved walkability
Mobility	The business park is separated from the residential areas by Commonwealth Avenue, making commuting less convenient by walking or cycling. Monofunctional districts with limited walkability.	Limited pedestrian and cycling paths, especially across the AYE and West Coast Highway, make it inconvenient for people to access their daily needs.	Traffic-free pedestrian areas with universal access within the residential zones create a more encouraging walking environment. The 5, 10, and part of the 15 min walking areas are well protected from vehicular traffic along the arterial roads surrounding the neighborhood.

). Their strengths and weaknesses were identified, and relevant strategies were then proposed with a view to making them better 15-minute neighborhoods (

Table 5. Analysis of Singapore’s three neighborhoods.

Analysis	Challenges	Opportunities
Part of Bouna Vista HDB and Holland Village	Low-rise residential and low density Monofunctional areas Limited walkability to cross major arterial roads	Increase density Increase mixed-use developments and Enhance connectivity between residents and different amenities Design continuous, accessible pedestrian and cycling paths
Clementi North and Central	Major roads and expressways fragment the area Public and transitional spaces are monofunctional Pedestrian and cycling paths are disrupted by major roads	Improve connectivity to stitch the fragmented areas Allow more flexible use of spaces and buildings over time Design continuous, accessible pedestrian and cycling paths
Toa Payoh Central	Cycle lanes are not continuous and in some areas are shared with pedestrian pathways	Widen and connect cycle lanes for continuity Allow for multiple/flexible use of spaces and buildings over time

).

Based on the findings, new strategies were proposed to enhance the 15-minute city framework. These strategies aim to improve chrono-urbanism by promoting the flexible use of spaces over time, increase vertical usage efficiency in high-density environments, and strengthen cycling networks to enhance connectivity.

Comparison of Neighborhood Adaptability

Through the case study analyses, distinct differences emerged regarding each neighborhood’s adaptability to the 15-minute city model:

Clementi North and Central

This neighborhood already demonstrates good adaptability with well-distributed amenities and strong mixed-use integration. However, fragmentation caused by major expressways limits connectivity, indicating a need for improved pedestrian and cycling infrastructure to fully realize the 15-minute vision.

Toa Payoh Central

The neighborhood exhibits strong foundational adaptability with its barrier-free environment and well-protected pedestrian pathways, making it highly conducive to active mobility. Nevertheless, incomplete and fragmented cycling lanes suggest room for enhancing connectivity, which could further solidify its status as an ideal model of inclusive mobility.

Holland Village (Buona Vista area)

The neighborhood presents lower adaptability primarily due to its lower-density, monofunctional zoning, and limited pedestrian connectivity across major roads. Despite its potential due to diverse job opportunities and amenities, significant adjustments are needed, such as densification, enhanced mixed-use planning, and comprehensive pedestrian/cycling network improvements, to fully align with the 15-minute city objectives.

Overall, Toa Payoh demonstrates the highest initial adaptability due to its inclusive, pedestrian-friendly planning, whereas Clementi shows moderate adaptability constrained mainly by infrastructure fragmentation. Holland Village requires substantial reconfiguration but holds significant potential if density and connectivity issues are effectively addressed.

5. Results and Discussions

5.1. Fifteen-Minute City: Proposed Strategies

Based on the previous analysis and the Singapore case studies, several strategies are recommended to create successful 15-minute neighborhoods in high-density contexts, incorporating principles from “chrono urbanism”—designing spaces to accommodate different uses over time, it envisions multiple uses for one place in order to offer more flexibility, according to the time of day—and fostering vibrant, adaptable communities [29].

5.1.1. Mobility and Connectivity

Multilayered Mobility Network

For high-density areas, a multilayered mobility system that prioritizes slow and active mobility should be created. Most ground-level space should be dedicated to slow mobility, incorporating green corridors, pedestrian paths, and community spaces. Private cars should be moved to the site’s periphery to enhance the efficiency and safety of these areas. The integration of public transport with multi-mobility transitions and choice should be made a priority (Figure 7).

Seamless Vertical–Horizontal Connectivity

We should ensure seamless movement of people between vertical and horizontal realms, emphasizing the ease and accessibility of transitions. This approach not only enhances connectivity but also promotes inclusivity, ensuring that everyone, regardless of mobility level, can access and enjoy the various amenities. Thyssen-Krupp’s rope-less MULTI maglev elevator allows multiple cabins to move vertically, horizontally, and diagonally within a single shaft, offering a high-capacity, barrier-free circulation system ideal for multi-story clusters [30].

5.1.2. Inclusivity and Comfort

Barrier-Free and Inclusive Design

To achieve inclusivity, neighborhoods must ensure that spaces are accessible to all, regardless of age, gender, or mobility level. Paths and public areas must be well designed with comfortable shading, seating, and rest areas for all users, supporting universal access and promoting active lifestyles.

Encouraging Sustainable Behavior

Policies and incentives should encourage residents to adopt healthier and more sustainable lifestyles. Promoting active mobility alongside public transport, supported by effective regulations, will help reshape behavioral patterns towards greater environmental responsibility and improved public health outcomes.

5.1.3. Mixed-Use and Vertical Development

Multifunctional Vertical Integration

Vertical stacking uses space efficiently, combining food production, greenery, public areas, and energy generation in one footprint, for example. This optimizes land use and blends functional areas, creating a vibrant and seamless urban interface. According to S. Nepomnyashchy, a 35-story “heliocluster” can deliver 100,000 m² of housing plus 100,000 m² of supporting infrastructure on just one hectare, illustrating the land-saving potential of compact, eco-friendly vertical neighborhoods [30].

Vertical Integration of Green and Public Spaces

By increasing and integrating landscape and public spaces vertically, we can provide more amenities like commercial areas, kiosks, art installations, and elevated biodiversity within easy reach. WOHA’s 2023 Pan Pacific Orchard stacks four themed sky-terraces—Forest, Beach, Garden, and Cloud—replacing 200% of the site area with greenery while keeping the ground-level Forest Terrace publicly accessible, proving that dense hospitality programs can still deliver generous biophilic public realms [31].

5.1.4. Time-Based Flexible Planning

Chrono-Urbanism Application

Chrono-urbanism, in the context of the 15-minute city, emphasizes “proximity” across both temporal and spatial dimensions. By reshaping neighborhood lifestyles from a temporal perspective, the flexible use of city amenities becomes crucial. For instance, time-based utilization of spaces allows a park to serve as a recreational area during the day and transform into a venue for film screenings or concerts in the evening. Additionally, pop-up spaces can regularly host flexible commercial activities, enhancing the vibrancy of urban areas [16].

Expanding on the implications of chrono-urbanism, it also involves organizing spatial structures to integrate active mobility flows, improve street connectivity, and align land use with the temporal dynamics of urban life. This integration ensures that neighborhoods remain accessible, adaptable, and responsive to the diverse needs of their communities.

6. Conclusions: Towards a New 15-Minute City Future

The paper advocated for a new 15-minute city framework for the high-density context of Singapore. It emphasized the relationship between space and time, urging a reevaluation of how time influences urban life. This rethinking aims to transition from a fast-paced lifestyle, characterized by lengthy commutes, to a more rhythmically comfortable urban life where valuable time is regained. The core principle of this framework is “proximity”. By strategically planning diverse amenities within a compact area, it addresses six fundamental social needs: civic, commerce, education, health care, business and leisure. This approach shifts from a monofunctional and segregated model to one of functional diversity and inclusivity, fostering a more connected 15-minute urban environment.

Aligning with Carlos Moreno’s perspective, the 15-minute city framework is flexible and scalable [16]. The framework emphasizes the importance of adapting service distribution and mobility options based on the density of an area. In areas with medium and low density, for instance, the temporal radius can be extended—considering a “30-minute territory” for low-density areas. Due to the characteristics of short-distance distribution and repetitive patterns in this model, particularly in high-density environments, adjacent areas tend to border and overlap, creating overlapping zones. These zones within neighborhoods may belong to different proximity zones and can be leveraged to plan shared, larger-scale, infrequently used amenities and cater to diverse demands that benefit a larger population. This approach ensures that the varying priorities of people’s needs are addressed, preventing shortages or surpluses of amenities. Additionally, it enhances connectivity and promotes shared well-being, improving community interaction, participation, and the “common good” [16].

We explored additional possibilities for high-density cities with limited land, such as Singapore, by focusing not only on horizontal space but also on the utilization of vertical space through 3D planning of amenities. This approach emphasizes vertical stacking, where diverse programs—such as residential, commercial, recreational, and green spaces—are layered efficiently within the same footprint. For instance, incorporating amenities like bike storage, shower facilities for cyclists, elevated green corridors, and vertical public spaces ensures active mobility is both practical and appealing.

To visualize this concept, we developed a 3D “vertical” model for urban scales of 5, 10, and 15 min of active mobility, inspired by the “Madrid flower of proximity”. This model examined the overlapping “petals” of accessibility, expanding both horizontally and vertically, to maximize land use and enhance connectivity. Our vertical framework also integrates direct linkages to key spaces such as MRT stations, schools, and community hubs, creating a seamless connection between essential urban services and residential areas.

This vertical stacking approach incorporates ancillary amenities—such as shaded pedestrian pathways, accessible lifts and ramps, and multi-use public spaces—to support walking and cycling, while the strategic integration of transportation nodes and social infrastructure further enhances urban connectivity and inclusiveness.

By creating direct, barrier-free paths, elevated linkways bypass road intersections and busy commercial corridors, providing uninterrupted, shorter walking routes that eliminate potential 10-min detours or multiple traffic lights; such a reduction in travel distances discourages the use of cars or private-hire vehicles for short intra-neighborhood trips, thereby minimizing vehicular emissions. In addition, multi-level integration of amenities allows facilities such as healthcare centers or daycare spaces to connect directly to residential towers or community hubs via overhead bridges. This convenience often encourages active travel or personal mobility device use, particularly when a trip of a few minutes on a sheltered elevated walkway replaces a longer, less comfortable street-level journey. The cumulative impact can be quantified, for instance, when a 15% shift in short-distance car trips (1–2 km) to walking or cycling reduces annual CO₂ emissions by a notable margin, underscoring the broader environmental benefits of such connections. By incentivizing active mobility even in challenging conditions (nighttime, rain, or intense heat), well-designed elevated links also promote healthier lifestyles and community interaction, extending the time window during which pedestrians and cyclists can safely use these pathways and, in turn, helping to displace more car trips overall (Figure 8).

Limitations and Future Research

Although the proposed strategies offer valuable insights for implementing the 15-minute city model in high-density contexts, several limitations should be acknowledged. Firstly, this research primarily drew from case studies and contexts specific to Singapore, characterized by its unique urban governance structure, climate, spatial constraints, and socio-cultural dynamics. Therefore, the transferability of these strategies to other high-density urban areas with different socio-economic frameworks or governance models might require careful adaptation.

Moreover, the proposed vertical stacking strategies and chrono-urbanism principles, while promising, may encounter practical constraints related to economic feasibility, regulatory frameworks, and long-term management challenges in different urban settings. These factors might limit immediate applicability without significant localized adjustments.

Future research should therefore explore comparative analyses across varied high-density urban contexts internationally to better understand the adaptability and scalability of these strategies. Additionally, empirical studies evaluating the long-term social, environmental, and economic impacts of implementing vertical integration and chrono-urbanism concepts across diverse urban typologies are necessary to strengthen the applicability and validity of the proposed framework.

This research provides a foundation that will help urban planners, architects, and city leaders to think and innovate more effectively in adapting the 15-minute city principles to varied and unique urban environments around the world, thereby enhancing sustainable urban development globally.

7. Glossary

Barrier-free and inclusive design: design approaches that ensure buildings, environments, and experiences are accessible to all, including people with disabilities, thereby supporting universal accessibility.

Chrono-urbanism: a planning concept that emphasizes the flexible use of urban spaces according to different times of the day to maximize efficiency and livability.

Multifunctional vertical integration: the practice of designing buildings and urban spaces to accommodate multiple functions within a vertical layout, such as residential, commercial, and green spaces, to optimize land use and enhance urban density.

Multilayered mobility network: an urban mobility layout that incorporates various modes of transportation stacked in different layers (e.g., subways, street-level pedestrian paths, and elevated bike lanes) to create a more efficient and accessible transportation system.

Polycentricity: an urban development model where functions and services are distributed across multiple centers within a city or region, reducing dependency on a single central area and promoting development in multiple hubs.

Transit Oriented Development (TOD): a strategy in urban design that promotes high residential and business density around transit stations to encourage public transport use, reduce reliance on cars, and foster pedestrian-friendly environments.

Vertical integration: the arrangement of different urban functions and facilities in a vertical format within buildings or urban projects to save space and enhance connectivity between different uses.

Vertical-horizontal connectivity: a design principle aimed at ensuring seamless movement and accessibility in urban environments both vertically (between different levels of a building or area) and horizontally (across the same level).