Gandong Cai and Mingjie Cai

2019 - Present






1 The Ignored Urban Mental Desire
The development of diverse disciplines resonates with the growing and evolving of human desires throughout history. The spatial design professions echo with such desire by organizing the built environment and managing the spatial systems. Environmental issues acquire more attention in the era of the Anthropocene along with the ongoing process of urbanization, emphasizing the importance of urban public health as the collective desire of all humans.

The Landscape Architecture profession is established on the understanding of the relationship between the improvement of the urban environment by human effort and public health. Currently, the standard for evaluating livability of a city relies largely on aspects such as the quality of public space, greening rate, and accessibility to parks. It is well discussed that landscape can accommodate emotion and relief pressure thus has a positive meaning to people's mental health: healing garden and therapeutic landscape as specific types of landscape can help to improve physical and mental health; contextual therapy theory in psychology also acknowledges the function of a picturesque environment in mental relaxation [1]. 

However, attention is largely paid to the physical aspect of public health. Kevin Thwaites points out that although the importance of enhancing human life quality through the design of urban space is well understood, it seems implicit that their capacity to help people mitigate the effects of mental fatigue may be assumed to accrue automatically as a by-product of other more general urban design principles [2]. This is demonstrated in two aspects: 1) the study of public mental health in planning and green space system scale is inadequate, and specific type of landscape like healing garden is incapable to tackle with systematic problems; 2) different groups of user have variegated mental desires in public space which cannot be addressed simply by a generic solution offered by the common urban open space (urban park). The landscape related to mental health is still functioning as a therapy within conventional medicine protocols and does not yet seem to have extended far into consideration of design in the wider public realm [3]. Thus, this essay introduces the conceptual project "Tokyo Loneliness Tree Hole Plan" which starts from the urban public space system and selects a specific group of users to analyze their mental desire in the urban environment, in order to explore the new possibility of advocating urban mental health through spatial design, and conceive the urban spiritual infrastructure which is a new systematic framework after the grey infrastructure and green infrastructure.

2 Design for Whom and the Recognition of Loneliness

It's a consensus to design public space for the public. Seeing the public as the majority of people, however, results in the neglect of the minority and their desires. The design of public space focuses on the typical majority: those who can freely behave in public space and enjoy the encounter and interaction with strangers. There is another group of people who are reluctant to bother others and unwilling to be disturbed--feeling nervous in crowded places--which are the "lonely" individuals that should not be ignored in the design of public space.

"Loneliness" has long been delineated as a negative emotion or mental condition and has been placed on the opposite side of "positive communication" and sharing, under the western binary context. Medical Sociologist Aaron Antonovsky establishes the theory of "Salutogenesis" [4], promoting the shift of modern medical science from the pathogenic orientation model which excessively focuses on the negative impact of potential illness and lowering sick risk, to the salutogenic orientation model that faces one's physical and mental health condition positively. At the society level, the pathogenic orientation model emphasizes the hazard of illness to alarm the people, while at the individual level it leads to the attention being solely focused on the disease once it is identified: either way lacks a synthetic understanding of the human complexity in health [5]. This resonates with the situation of the lonely individuals in the city who are suffering from the pressure of being lonely, while society is indicating the danger of loneliness and the necessity of eliminating loneliness ①. Scholars from the landscape architecture profession have applied the salutogenic orientation model and pointed out that urban landscape has the potential to relieve mental stress and generate a positive understanding of the mental condition by offering a pleasurable experience [6]. We believe the urban environment should follow the Salutogenesis theory and create a new understanding of loneliness, by encouraging the public to get along with loneliness through spatial design methods.

3 Site Selection and Research Methods

"Tokyo Loneliness Tree Hole Plan" is the first-prize-winner proposal of the Eliminate Loneliness Idea Competition. The proposal targets the loneliness issue in Tokyo as a response to the topic of Design for whom. The behavioral mode of self-restraining and keeping social distance in Japanese public life, together with the extremely high living pressure and demographic density, lead to the prevalence of loneliness in every corner of the city--the lonely individuals are the minority users in public space and the majority in Tokyo at the same time. Furthermore, "loneliness" as an oriental aesthetic concept emphasizing the status of getting along with oneself, has been reflected in lots of art and literature pieces ②, which justifies and unifies the selections of both the topic and the site: to establish a new cognitive mode of loneliness based on the Salutogenesis theory in a city dominated by the phenomenon and aesthetics of loneliness by the method of spatial design. For this purpose, the proposal starts from the study of mental desire and aims at providing suitable space for getting along with loneliness, through mitigating the negative impact of the mental status.

4 Urban Tree Hole: The Empathy about Loneliness between Human and Nature

The lonely individuals concern less about the feeling of loneliness per se than the way loneliness is treated by society and the impact on others by being lonely. As an antidote to loneliness and a strategy for depathologizing it, privacy may be as effective as company for these people [7]. They might prefer to talk to a “tree hole”: a space that can be easily found around, will not respond and disturb others, but provides enclosed shelter and the feeling of safety. Anyone who wants to spend some time alone can go into such space without worrying about the outside world.

Thwaites points out that a restorative urban open space structure is emerging [8]: moves away from the idea of large discrete open areas to more of a web or mesh-like structure that links together a system of smaller spaces, whose quantity and high accessibility in cities have the advantage in tackling mental issues in a timely manner. The "Tokyo Loneliness Tree Hole Plan" proposes such a spiritual infrastructure network of small "urban tree holes" as a systematic maneuver to provide the lonely individuals in Tokyo a chance to get alone with themselves, with the space, and with loneliness.

Shibuya, the center of Tokyo, is selected as the site for implementing the plan. On one hand, as the major commercial center and the most stressful area to live and work, Shibuya perfectly represents the Tokyo loneliness; on the other hand, given that only 6 percent of Tokyo's urban area is classified as open space [9], Shibuya with the highest building density in the city is desperate for the "urban tree holes" to be inserted. The project proposes operative tree hole prototypes according to specific site conditions and conceives three different spatial modes to create innovative public space in Shibuya by utilizing street retail spaces, sky corridors, and underground spaces.

Instead of creating an isolated place for people to stay in, the tree hole space invites accompanies from nature such as tree, sky, and water to the users, by a sequence of spatial design strategies. Roger Ulrich proves the function of natural element in elevating people's mental health by the observation of a group of patients who experience considerable anxiety [10]: the patients with the tree view had better performance in overcoming frustration, fewer negative evaluative comments, and shorter post operative hospital stays, compared to the wall-view patients. As the most common natural elements, tree, sky and water are ignored in the high density and fast-paced urban life--they are silent and lonely in the city. Through the enhancement of the loneliness aesthetics between nature and people, the project attempts to establish the oriental concept of empathy: human and nature can "share" and "communicate" the feeling of loneliness temporarily.

4.1 Urban Tree Hole_01: Renovate Street Retail Space

The retail spaces along the street interface with fast iteration speed have great potential to be transformed and embedded the small-scale public space in Shibuya, where the density of commercial and cultural activities is extremely high. The design strategy of Urban Tree Hole_01 focuses on the way of seeing by switching the interior and exterior spaces. The tree hole spaces are hidden in the urban context by the design method of embedment in renovated stores along the retail street, which reduces the impact of the original urban interface. From the exterior, a two-side mirror as the new façade of the renovated space reflects the image of the user and the background city; from the interior, the mirror separates the city and the user who is pulled away from the context and obtains a moment to rediscover the overlooked landscape in the city she originally familiar with. The technique of borrowing scenery is used to involve in the tree hole the street tree which becomes a companion and listener of the tree hole user. As the new city spiritual infrastructure, the embedded tree hole spaces that distribute in the city but hide in the street context provides the citizen a moment of meditation with a Zen-garden-like experience.

4.2 Urban Tree Hole_02: Utilize Sky Corridor

While the vertical transportation mode depending on the elevators represents an important movement in high-density cities, the sky corridors between buildings become one kind of horizontal connected open space for promoting the openness and publicity of the overhead space. Though the sky is originally a part of the cityscape, congested high-rise buildings in the city make people gradually lost the instinct to look up at the sky--climb up to the skyscraper and overlook the cityscape becomes the normal viewing mode. Through the strategy of obstructive scenery and sight manipulation, the Urban Tree Hole_02 utilizes sky corridor between buildings to create space for users to briefly stay alone. Compare to the common sky corridor that emphasizes transparency, the tree hole's external scenery is deliberately blocked by sidewalls. Only the sky is reflected by tilted mirrors on both sides of the corridor, which forces the user to focus on the mirrors by his feet. Consequently, a spiritual infrastructure is established through the sky corridor tree holes built between buildings in the city, and the user can look down to meet the sky which should have been found by looking up. Thus, people and the forgotten sky achieve an empathetic moment on both the physical and mental levels.

4.3 Urban Tree Hole_03: Excavate Underground Space

The street interface and high-rise buildings occupy the visible ground and overhead space in the city. The underground, however, is an invisible potential space in the city. By locating the Urban Tree Hole_03 as the small-scale public space below the busiest intersection in Shibuya, the tree hole space provides a quiet place in the busy city. Except for the underground part, the design of the tree hole_03 also includes a rain garden above ground. Since no one will care about where the falling rain is going to in the center of a highly-dense metropolitan city, our strategy for the tree hole intend to collect and filler the city runoff water, and to transform them from invisible raindrops into a visible water feature in underground space. The water curtain can effectively block the ground noise at the same time, which helps to create a place for users to get along and communicate with the nature element—water. From above ground to underground, from never being noticed to being the focus, our strategy—scenery replacement—turns the originally invisible city underground and raindrops into the visible empathetic objects for the lonely users.

4.4 Use and Management of Urban Tree Hole

Besides the spatial design strategies, the “Tokyo Loneliness Tree Hole Plan” considers two questions simultaneously: how to convey the enjoyable experience of getting along with loneliness, and establish a “comprehensive share structure” among citizens through using this new type of public space? Therefore, the <Tokyo Loneliness Tree Hole Guide> is introduced in the project. This guidebook not only shows the locations and instructions of the urban tree holes but also provides a message board for the users to write down and share their lonely story and the experience in the tree holes. In this way, users are circulating and sharing the <Tree Hole Guide>, transforming it into a collective communication tool for each lonely individual.

Also, to balance the publicity and privacy, security and management issues, each tree hole’s design is based on the scale for one person use, and intend to be operated by a reservation mechanism, through which only one user can enter and use the space at a specific time--a “One Person, One-Time” place is created. The “One Person, One-Time” operation mode ensures that the users can enjoy the space exclusively for a specific time, and the effective reservation mechanism allows the public to take turns to use the space orderly. These urban tree holes propose a new possibility for public life which cannot directly apply the use and management model of the traditional urban public space, given that the two are significantly different. Therefore, the reservation mechanism of “One Person, One-Time” combines with the <Tree Hole Guide>, can support the operation mode of this new type of future public space, which becomes the new infrastructure network in the city.

5 One Person Park: The Possibility of Future Public Space

While the modern city has a clear definition of what is public-owned and private-owned space through the land use and ownership division, there is ambiguity between public and private when it comes to practical issues. Currently, the discussion regarding the vagueness of public and private mainly focuses on the space that is "privately owned but opens its external areas to the public in order to provide more urban open space" [11]. "Tokyo Loneliness Tree Hole Plan" is something different: it proposes space that is public, but offers people a temporary and private place for solitary use through a "one person, one-time" mode. The concept of "private-public space" aims at criticizing the indifference against the diversity of the users' mental desire in the current public space, breaking the banal boundary between public and private, and exploring the possibility of future public space with vagueness--the "One Person Park".

"One Person Park" as a concept has not been discussed before it is mentioned in this essay. Its major differences against traditional urban green space are: 1) while the traditional park is merely public, the "One Person Park" can shift mode between public and private through management; 2) compare to traditional park that occupies a great amount of urban land, "One Person Park" is inserted into the existing urban systems; 3) traditional park owns abundant resource of landscape, while "One Person Park" absorbs adjacent natural elements as the supplement of landscape resource. It is the vagueness in both the ownership status and the spatial image of "One Person Park" that makes it a void yet a promised space of expectation in the public space system [12]. Far from the retrogression of publicity and going back to the private garden or private owned space, "One Person Park" suggests a new communication mode on public sharing.

While "One Person Park" has not been fully discussed yet, the exploration of private use in public space has started. A temporary public art event--Concert For One--was brought to Boston, the US in 2019, which provided a chance for one instrument player and one audience to stay in a solitary space for one minute, thus successfully created a private music experience for public space user ③. This art project echoes with the "One Person Park" in the challenges they point out to the current public space function: in an era when interacting programs such as music plaza and amphitheater are everywhere and becomes the stereotype in public space design, can we imagine a new form of public landscape that allows the user to enjoy being alone?

"One Person Park" as an alternative possibility for future public space development should earn more attention in the discussion of urban space design. The COVID-19 pandemic urges us to consider the issue of public isolation and non-contact communication, as well as the new way to use the current public space. There is a huge conflict regarding behavioral mode between the openness and interaction in public space and the hygiene protocols of avoiding physical touch during the pandemic. To what degree can current public space design reflects and addresses the physical and mental desire of the city dwellers? How can the concept of "One Person Park" enrich and complement the study of urban public life?

6 Conclusions

This essay investigates the mental desire in public space through the introduction of a conceptual design project, proposes a set of spatial strategies for eliminating the public's prejudice against loneliness, and offering suitable public space for the lonely individuals living in cities through the study of different scenarios. As a competition entry, "Tokyo Loneliness Tree Hole Plan" brings up three operational prototypes as well as intervention modes instead of construction guidance for any designated site with specific technologies. Thus, the project concerns less the management issues when the tree holes are implemented in reality, than the discussion of its value in exploring mental-oriented design intervention in urban space development. Furthermore, given that urban loneliness is not the only mental health issue in our cities, the strategy applied should be various regarding different mental desires. The thoughts and ideas that emerge in "Tokyo Loneliness Tree Hole Plan", however, have the reference value for public space planning and design in the future.

In the period of post-pandemic, with people's tendency to stay alone or restrict getting together in public space, how design can fulfill the new desire--especially the mental desire--becomes the new agenda for designers. Mental health awareness needs to be integrated into all elements of health and social policy, health-system planning, and health-care delivery [13], including the design and construction of urban public space and infrastructure. More ideas based on specific background, city, and public desire should be taken into consideration in the future, in order to promote new discussion and practice in a broader territory and context.


1 被忽视的城市精神需求





2 为谁设计与认知孤独


“孤独”一词在西方二元论语境下长期被渲染成一种与“积极交流”“分享”相对立的消极精神或情绪状态。医学社会学家阿兰•安东诺夫斯基提出“健康本源论”(Salutogenesis)概念[4],认为现代医学应从过度关注潜在疾病可能对身体产生的负面影响、主张规避风险的疾病本源导向,转为健康本源导向(Salutogenic Orientation)的认知模式,即直视自我的身心健康状态。疾病本源导向在社会层面上表现为强调疾病危害性以起到社会警惕作用,在个人层面上则表现为注意力被过度集中在疾病本身:两者都缺乏对健康复杂性的综合认知[5]。这与城市中的孤独群体面临的状况相似,即社会强调孤独的危害而强调消除孤独①,个体也因自身的孤独产生心理负担。关于健康本源导向模式在空间营建学科上的应用,已有景观学者指出,城市中的景观空间能营造令人愉悦的氛围,减缓压力,有利于产生积极的心理认知 [6] 。笔者认为,社会环境应以健康本源导向的理论为支撑,通过空间营建的手法更新人们对孤独的认知,鼓励大众学习与孤独相处。

3 项目选址与研究方法

“东京孤独树洞计划”是2019年“消除孤独概念竞赛”(Eliminate Loneliness Idea Competition)的一等奖作品。方案选择以“东京孤独”作为城市精神需求的研究对象,一方面是对“为谁设计”议题的回应。日本公众在公共生活中自我克制与注意保持社交距离的特质,加之东京地区极高的生活压力与人口密度,导致了孤独感渗透在城市的每个角落——在东京,孤独者既是公共空间使用群体里的小众,又是这座城市无处不在的大众。此外,“孤独”在东方思维中作为一种强调与自我相处的美学,在艺术与文学作品中反复出现②,使得本方案的选题与选址理由更为充分与统一:在一座具有孤独现象与孤独美学的城市,利用空间设计的手法,建立基于健康本源论的孤独认知模式。为此,方案从精神需求层面入手,通过疏导孤独感带来的负面影响,旨在为孤独者提供适宜的享受孤独的空间。


4 都市树洞:人与自然关于孤独的共情





4.1 树洞一:改造临街商铺


4.2 树洞二:空中连廊



4.3 树洞三:开发地下空间


4.4 都市树洞的使用与管理


另外,为了兼顾空间的公共性与私人性,以及安全与管理问题,项目在空间设计上基于一人使用的尺度,采用分时预约使用制,即同一时段只允许一位使用者进入,营造“一人一时”的场所。 “一人一时”保证了使用者能在特定时间内独享空间,而一套有效的预约机制则使得公众能有序地轮流使用。这种都市树洞为公共生活提出了一种新的可能,但因为其特征与传统的城市公共空间有较大差异,无法直接沿用后者的使用与管理模式。“一人一时”的预约制度结合《树洞指南》手册,共同支撑起这种新型未来公共空间的运作模式,使之成为城市中新的基础设施网络。

5  一人公园:未来公共空间的可能性



“一人公园”概念虽尚未被广泛讨论,但对于公共空间中独处功能的探索已有案例。美国波士顿曾于2019年举行了一场城市临时公共艺术活动——一人音乐会(Concert For One),其在城市公共空间中创造出一名演奏家为一名听众演奏的一分钟音乐会,让使用者拥有一次在公共空间中享受专属一人的音乐体验③。该项目与“一人公园”异曲同工之处在于对现有公共空间的功能发出的挑战:在音乐广场、户外剧场等鼓励集体参与的功能性空间成为公共景观陈词滥调的今日,是否可能出现一种新的景观形式,允许空间使用者享受一人一时的乐趣?


6 设计反思




① This project is the entry proposal of an international competition under the topic "Eliminate Loneliness". The use of "eliminate" reflects the social tendency of seeing loneliness as a disease and negative issue. The proposal is entitled "from Eliminating to Elevating" with the hope of overturning such negative understanding of loneliness, and suggests a new way of thinking.

② It is commonly acknowledged that loneliness has an important position in Japanese aesthetics and philosophy, which can be found in concepts such as "Wabi-sabi" and " Mono no aware ".

③ This event is launched by the Celebrity Series of Boston and Musician Rayna Yun Chou for 10 days, which is installed and exhibited in the public space of Boston Chinatown and Harvard Plaza in Cambridge.

 ①本项目参加的国际竞赛主题为消除孤独(Eliminate Loneliness)。使用“消除”一词反映了孤独被看作一种病症和负面问题对待。本项目的参赛标题为“从消除到升华”(from Eliminating to Elevating),意图是推翻对孤独的负面理解,提出一种新的思考方式。


③活动由波士顿名家系列(Celebrity Series of Boston)与音乐家周韵(Rayna Yun Chou)发起,活动期10天,分别在波士顿中国城以及坎布里奇的哈佛广场公共空间上展出。


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