Moving Urban Sculptures towards Sustainability : The Urban Sculpture Planning System in China

Following the continuous development characterized by large-scale constructions, Chinese urban development has shifted to the promotion of refined urban space quality. Urban sculpture, an important part of public arts, has been receiving increased attention in China as an important carrier for highlighting urban characteristics, culture, and history within cultural policies. As a type of cultural capital, it offers innovative methods to address the issues of economic, social, and environmental sustainability, in particular cultural sustainability. Interdisciplinary theories of urban planning are creatively applied to guide, coordinate, and improve the sustainable production of urban sculptures in China. This research was initiated to: (1) Illustrate how urban sculptures are produced through an urban planning system in the context of China; (2) explain what kind of influencing factors in relation to sustainability exist, mainly within the framework of planning strategies and cultural policies; and (3) put forward sustainable planning strategies to produce urban sculptures. To answer the above inquiries, we reviewed more than 100 articles, plans, and government documents, and we conducted several semi-structured interviews. The article argues that urban planning strategies and policies have been conceived as strategic instruments by the Chinese municipal governments to realize sustainable development of urban sculptures. Our findings would enrich knowledge on geographic studies of public art planning through the contextualized analysis of a Chinese urban sculpture planning system. It also fills the gap in the literature on the sustainability of urban sculptures by approaching the perspectives of planning strategies and cultural policies.


Introduction
Ancient Chinese sculpture has flourished with a long history, boasting a splendid civilization.However, the actual placement of sculptures in urban public spaces began in the Republican era , as the concept of government authority-oriented memorial sculptures was imported from the West.Consequently, the wars and political movements stagnated the construction of urban sculptures.Since the 1980s, the construction of urban sculptures has been revived and has begun to develop dramatically.Since the economic reform in 1978, Chinese cities experienced a historic period of transition from a planned economy to market economy [1].The industrial structure of several Chinese cities shifted from the traditional economy of manufacturing to a consumption-based economy, especially the cultural consumption industry.The conflict between the development of urban construction and the protection of urban features is always a problem faced during the process of urban development, especially in a post-socialist context [2].The importance of art has gradually been granted within social policies in the economy, politics, and culture [1,3].
The concept of an "urban sculpture" emphasizes the notion of "urban" and highlights its interactive nature with the surrounding urban environment.This specific definition was put forward in 1985: "Urban sculptures refer to the sculptures those built on roads, squares, green spaces, residential areas, scenic spots, public buildings, and other event venues within the urban planning areas" [4].Internationally, urban sculptures are usually categorized as public art (Table 1).Public art refers to permanent or temporary works of art that are located in places accessible to the public, including a variety of spatial forms, material media, and expressions.Public art refers to the art form that public institutions have used public funds to place them in public spaces, and the art itself often emphasizes its public nature [5][6][7].Although China has gradually begun to pay attention to diversified public art installations, urban sculpture has occupied a more important position in the production of Chinese public arts in the past few decades.It can be seen from the plans, official documents, and policies that they are focusing more on urban sculptures than other kinds of public arts (see more in Appendix A).Urban sculpture can, therefore, be seen as a kind of contextualized production of public art in China that corresponds to its international context.

Intangible
Event, performance, or gathering (temporary activity); oral history or cultural expressions passed on from generation to generation Source: Based on the report of "The role of the arts and culture in planning practice" [8].
Public art has been utilized as a strategy for sustainable urban living by many cities and regions [9] (p.9).It is generally recognized to respond to a number of urban issues in environment, economic, social, and cultural development [10][11][12].Extensive researchers have claimed the benefits of public art on the improvement of the quality of the environment [13]; activation of living communities [1]; city marketing [14]; promotion of tourism [15]; development of sustainable tourism [16]; strengthening social equity [13]; enhancement of social cohesion [17]; improvement of urban image [17]; formation of urban identity [18]; economic, social, and physical urban regeneration [19,20]; vandalism reduction [21]; rehabilitation of post-industrial sites [16]; development of a "sense of place" [13]; and construction of a cultural landscape [22], etc.There are three pillars of sustainability: Ecological, economic, and social, with culture included as the fourth pillar [23][24][25].Katriina Soini and Joost Dessein elaborate "culture in sustainability" and recognizes cultural capital in different forms as arts, heritage, knowledge, and cultural diversity [24].Excellent urban sculptures can respond to the issues of sustainable urban development in the above four pillars, especially culture sustainability [26].
The definition of "sustainable development" adopted here is based on the 1987 report of the World Commission on Environment and Development (also known as the Brundtland Report) that it "meets the needs of the present without compromising the ability of future generations to meet their own needs" [27,28].As for the notion of "sculpture sustainability", it is usually examined from the perspectives of "ecological arts" and "environmental arts" [26,[29][30][31][32].A lot of academic improvements have been made in achieving the maximum use of original materials and modern environmentally friendly materials in the design of sculptures, such as low-carbon materials and recyclable materials [33][34][35][36][37].However, few studies have examined "sculpture sustainability" from the perspective of planning strategies and cultural policies.Sustainability is defined as a development model that includes certain policies that are adopted to reduce energy consumption and pollution, promote cohesion for the harmonious development of people and cities, and encourage efficient landscape design [38,39].Problems of unsustainable development should not be merely spontaneous social products, but planning should be utilized as a means guided by policy makers and stakeholders to avoid unsustainable outcomes [38].We can therefore see that planning strategies and policies are actually important determinants of whether urban development can be sustainable.As for sculpture sustainability, planning strategies and policies also play important roles.Policy making is regarded as an important factor in the production of public art, as discussed in studies by several researchers, such as Cartiere and Willis [7], Chang [40], Miles [41], Selwood [10], and Senie and Webster [42].Martin has also demonstrated how different cultural policies have shaped the divergent public-art productions [43].Pollock and Paddison have pointed out that it is better to embed the public art within institutional structures [44]."Cardiff Public Art Strategy" also states that the development and integration of public art should be actively encouraged throughout the planning policy framework [45] (p.13).All these research and practices have provided a robust conceptual basis for this article.However, few researchers have unpacked how planning strategies can be utilized, and what kinds of policies can be utilized in order to promote the sustainability of urban sculptures.It is, therefore, crucial to fill the research gap of sculpture sustainability from the perspective of planning strategies and policies.
Most of the current studies written in English on public art planning focus on European-American contexts.These studies rarely focus on Asian contexts, which are characterized by different social structures and management [4].In particular, urban sculpture and its planning systems in China have not been comprehensively examined.Chinese cities have applied urban planning theory creatively in the field of urban sculpture [46].Urban sculpture planning is formulated to take all aspects of sustainable development factors into account.Examples of the factors include ensuring that the overall planning and arrangements take into consideration the required conformation with the dynamic urban space development, as well as making sure that the development focus of urban sculpture correlates with the major urban heritage preservation and cultural landscape construction projects.In the practices of international regions and cities, planning has also been utilized as a tool to lead to the long-term production of public art, as playing a full role to the coordination role of planners to endeavor to strengthen the effects of promoting the healthy development of culture and economy, such as the "Fort Worth Public Art Master Plan" [47], "Louisville Public Art Master Plan", and "Enhancing Singapore's City Landscape: The Public Sculptures Masterplan 2002" [48], etc.We can see, therefore, that some issues of sculpture sustainability are not unique to China.The investigations into Chinese urban sculpture planning systems could also present local experiences for global issues in other countries and regions.China was chosen as the main research object because it has an urgent need for a sustainable development model, following the rapid and large-scale development of urban sculptures, which is reflected in the sharp increase in the number of urban sculptures.Taking Shanghai as an example, the number of urban sculptures has increased from 1500 pieces in 2003 to 3500 in 2015, and many of these are large-scale, fixed sculptures.As a result of this concentrated and explosive development, several unsustainable issues have arisen.Faced with these problems, how can we realize the human-centered principle of intergenerational equilibrium to meet the needs of contemporary people and leave room for our future generations?How can we achieve harmonious development of sculpture and dynamic development of urban space?How can we achieve ultimate cultural and social sustainability through the continuous development of urban sculptures?How can we make urban sculpture develop in a long-term and healthy way?These questions are all related to urban sculpture sustainability.
Consequently, this article differs dramatically from the existing literature, not only because of the different perspectives, but also because of the geographic areas in which it was conducted.The main purpose of this article is to put forwards sustainable principles from the perspectives of planning strategies using the case studies that mainly focus on a Chinese context.For this purpose, our research questions are the following: (1) How are urban sculptures produced through planning systems in China's context?(2) What kind of influencing factors are related to sustainability, predominantly within the framework of planning strategies and policies?(3) What kind of principles for planning strategies and policies could be utilized to move urban sculptures towards sustainability?Our findings will be valuable to both policy makers and other urban actors, such as urban planners, artists, and architects, in crafting strategies for the sustainable production of urban sculptures by improving planning efforts.Moreover, the results will also add to the knowledge of geographic studies of public art planning through the contextualized analysis of Chinese urban sculpture planning systems.

Materials and Methods
We first conducted a comprehensive search of scientific publications from the China National Knowledge Infrastructure (CNKI-http://www.cnki.net/)and Web of Science Direct, using different search terms and combinations, as shown in Table 2.As urban sculpture is an important part of public arts in international contexts, the term of "public art" was also used to make sure related studies could be included.Following the searches, we eliminated the repetitive studies in different databases to make sure the data was not covered more than once in the analysis.As a significant proportion of urban sculpture planning research is not published in peer-reviewed journals, we also used Google Scholar to get more articles by an extensive subjective search.As was previously stated, one of our aims was to describe the development history so we did not define the time limit to get as much information as much as possible (-May 31, 2018).In addition, planning and policy documents were collected from open sources, such as local official planning bureau websites, and from personal contacts with unpublished documents.
In the database of Web of Science, we obtained 31 studies of peer-reviewed scientific papers and conference papers.We obtained another 95 studies of peer-reviewed articles, 31 newspaper articles, and 26 theses of PhDs and Masters from the CNKI database.We then verified the relevance of these studies through article titles, keywords, and abstracts, resulting in 126 articles in two languages (English; Chinese), which specifically dealt with urban sculpture planning of China.Another 31 urban sculpture planning and policy documents were also included in this research.Because urban sculpture planning studies are closely related to actual practices, the studies were also checked by the standards whether it contained cases for specific cities.The 37 studies with cases were the core materials for the review.To make some comparative studies, another 31 foreign (including Asia, European, Australian, American cities) public art master plans and related literature were collected through searching "public art master plan" on Google and Google Scholar.
Each paper was examined according to the following descriptive attributes in the established analysis framework of this research, as listed in Table 3.This framework was formulated based on preliminary fast literature reviews with the main research objectives in mind.Initially, some aspects were targeted to gather basic information, such as when, where, why, by whom, and how the research and practice took place.According to the framework, related literature materials were reviewed one by one.As a result, the targeted inquiries could be conducted according to the analysis and a summary of the information reviewed, such as the status quo of urban sculpture development in Chinese cities, the problems of urban sculptures' development before planning and strategies of planning, and also the different strategies utilized in the planning practices to move sculptures towards sustainability.Other qualitative methods were also utilized in this study, such as semi-structured interviews with key actors of government officials in the Municipal Urban Planning Bureau, artists, urban planners, architects, landscape architects, residents, etc.These interviews were mainly designed as supplementary materials to identify the effects brought by sculpture planning documents and policies to the cities in relation to sustainability.The interviews were structured by several questions of "why, how, what".For example, why is the sculpture planning important for the sustainability of sculptures?(the "why"); how does the urban sculpture planning contribute to the sustainability of sculptures?(the "how"); and what actual effects does the planning and policy have after the implementation?(the "what").The descriptive method was also utilized in this research to study the development of the urban planning system in China based on the literature examination.

Situating Urban Sculptures within Chinese Cultural Policies and Urban Planning Systems
Urban sculpture, as an important part of cultural strategies, varies with different social and political contexts [43,49].Cultural policy "refers to the institutional supports that channel both aesthetic creativity and collective ways of life . . .Cultural policy is embodied in systematic, regulatory guides to action that are adopted by organizations to achieve their goals" [43,50].Before the Chinese economic reform (1978), the development of urban sculpture was influenced largely by political factors, with commemorative urban sculptures in realistic styles, such as statues of historical celebrities, peasants, and soldiers (Figure 1).The sculptures were regarded as a political tool of maintaining social order, which could produce monuments to stimulate civic identities and nationalism.Since 1980s, urban sculpture was utilized by Chinese cities as a driver of local economies, local tourism, urban-upgrading, and sociocultural urban regeneration.The "National Urban Sculpture Planning Group" (chengshi diaosu guihua zu) was established with the approval of the Ministry of Culture and the Ministry of Construction in 1982.Subsequently, various cities and provinces across the country have set up special institutions to promote urban sculpture construction.In order to strengthen the construction and management of urban sculptures, the national regulation of the "Administration Regulations of Urban Sculpture Construction" (chengshi diaosu jianshe guanli banfa) was issued by the Ministry of Culture and Construction in 1993 [46].It marked the point at which the construction of urban sculptures in China began to enter the track of legal systematic management.The cities of Seattle, Birmingham, Melbourne, and Singapore are all excellent examples of regenerating urban economies, beautifying city spaces, and fostering a sense of identity through arts and culture [40] (p.1921).Thus, urban sculptures were also taken as new ways to increase urban economics and competitiveness because of its effects of imaging cities in postsocialist China.In order to integrate the urban sculpture construction into the management systems of urban planning, the Ministry of Construction has undertaken the role of guidance, which further clarified the function of construction management [51].In 2005, the Ministry of Construction carried out the "Public Art-Percent Investment Policy Research (gonggong yishu baifenbi touzi zhengce yanjiu)" to conduct research and analysis on the public art policies, financial factors, and development trends of domestic and foreign cities [52].In 2006, "Guiding Opinions on Urban Sculpture Construction (guanyu chengshi diaosu jianshede zhidao yijian)" (No.137 [2006]) has been issued to guide urban sculptures' construction from aspects of project establishment, site selection, design examination, etc.Based on the establishment of urban sculpture management agencies and the formulation of relevant regulations, urban sculpture construction has gradually been incorporated into urban planning systems throughout the country [53].Urban sculpture planning is a suggestive document, which is linked to the original urban planning system, providing a platform for joint work of professional practitioners from different majors, including urban planning, art, landscape, architecture, municipal administration, transportation, etc. Song Chunhua, the Deputy Minister of Construction, in his speech at the Changchun sculpture construction conference, proposed that urban sculpture has already entered the "planning era (guihuashidai)" [54].Urban sculpture plans are usually formulated as a part of overall master plans (chengshi zongti guihua) or a single special plan (zhuanxiang guihua) [55].According to incomplete statistics, from 1996, more than 38 cities (See details in Appendix A) have compiled urban sculpture planning documents.Since the 1980s, more than 10,000 urban sculptures in China have been constructed [56] (Table 4).The number of sculptures in many cities have increased significantly.However, due to the lack of corresponding planning, management regulations, operational mechanisms, and other policy measures, the urban sculpture construction of some cities has been under chaotic situations.Before the formulation of urban sculpture planning, most of the cities would do a thorough investigation on In order to strengthen the construction and management of urban sculptures, the national regulation of the "Administration Regulations of Urban Sculpture Construction" (chengshi diaosu jianshe guanli banfa) was issued by the Ministry of Culture and Construction in 1993 [46].It marked the point at which the construction of urban sculptures in China began to enter the track of legal systematic management.The cities of Seattle, Birmingham, Melbourne, and Singapore are all excellent examples of regenerating urban economies, beautifying city spaces, and fostering a sense of identity through arts and culture [40] (p.1921).Thus, urban sculptures were also taken as new ways to increase urban economics and competitiveness because of its effects of imaging cities in post-socialist China.In order to integrate the urban sculpture construction into the management systems of urban planning, the Ministry of Construction has undertaken the role of guidance, which further clarified the function of construction management [51].In 2005, the Ministry of Construction carried out the "Public Art-Percent Investment Policy Research (gonggong yishu baifenbi touzi zhengce yanjiu)" to conduct research and analysis on the public art policies, financial factors, and development trends of domestic and foreign cities [52].In 2006, "Guiding Opinions on Urban Sculpture Construction (guanyu chengshi diaosu jianshede zhidao yijian)" (No.137 [2006]) has been issued to guide urban sculptures' construction from aspects of project establishment, site selection, design examination, etc.Based on the establishment of urban sculpture management agencies and the formulation of relevant regulations, urban sculpture construction has gradually been incorporated into urban planning systems throughout the country [53].Urban sculpture planning is a suggestive document, which is linked to the original urban planning system, providing a platform for joint work of professional practitioners from different majors, including urban planning, art, landscape, architecture, municipal administration, transportation, etc. Song Chunhua, the Deputy Minister of Construction, in his speech at the Changchun sculpture construction conference, proposed that urban sculpture has already entered the "planning era (guihuashidai)" [54].Urban sculpture plans are usually formulated as a part of overall master plans (chengshi zongti guihua) or a single special plan (zhuanxiang guihua) [55].According to incomplete statistics, from 1996, more than 38 cities (See details in Appendix A) have compiled urban sculpture planning documents.Since the 1980s, more than 10,000 urban sculptures in China have been constructed [56] (Table 4).The number of sculptures in many cities have increased significantly.However, due to the lack of corresponding planning, management regulations, operational mechanisms, and other policy measures, the urban sculpture construction of some cities has been under chaotic situations.Before the formulation of urban sculpture planning, most of the cities would do a thorough investigation on the development status of the urban sculptures, including the number, location, image, and some other details of the sculptures.This helped to summarize the problems existing in the current situation, and then solve them through corresponding methods during the formulation of sculpture planning documents.Through the analysis results of the literature review for the current situation of urban sculpture development (based on the framework in Table 2), the factors in relation to sustainability for the current situation could be conducted and classified into four aspects (Table 5).In addition, these four aspects are related to the values corresponding to sustainable urban development, such as environmental, cultural, economic, and social values [57,58].According to the above analysis, these current issues in relation to sustainability could be listed as follows:

•
Lack of systematic coordination.Due to the market-oriented urban sculpture construction, the overall distribution of urban sculptures in many cities is uneven.Most artists usually work in their own independent fields without consideration of the relationships between these sculptures and other existing ones [59].In particular, the lack of an overall arrangement for characteristics and themes of urban sculptures results in a singleness of form and the duplication of subject matter within the proposed site vicinity.This will not only lead to a waste of urban resources, gentrification of certain areas, and increasing disparities, but it can also be detrimental to the principles of equity balance.In addition to the fairness of the urban sculpture layout, urban sculptures should be given priority in areas in which they are relatively scarce [60].

•
Loss of cultural identity.Affected by cultural globalization, China has also been influenced by Western art.There are too many similar sculptures emulated from the West, making it impossible to construct a unique urban cultural landscape [61,62].The sculptures are mass-produced by factories as industrial products without cultural meaning, formal sense, or taste in art [63].The mass production of these urban sculptures aggravates the phenomenon of "thousands of cities with one appearance (qian cheng yi mian)".There is a lack of understanding of regional culture, especially in works responding to regional culture [64].

•
Reduction of life cycle.The life span of urban sculptures includes both their physical life and artistic life [65].Lack of research on sculptural materials and production techniques results in their reduction in the physical life span.Materials should withstand climatic conditions, such as sun, heat, and freezing as well as winter salt exposure.There is no corresponding policy to strengthen the protection of existing urban sculptures, so professional maintenance and repairs cannot be carried out [59].What is more important is the abnormal shortening of the urban sculptures' art life, which is demonstrated by their disharmony with the surrounding environment.An inconsistency of characteristics, such as theme, site selection, and material, could result in relocation or dismantling only a short period after the sculpture was constructed [66].These processes cause a waste of construction funds, manpower, and resources [65].For Chinese cities, the urban space holding sculptures may change due to rapid urbanization.For example, the statue of Sun Yat-sen in Nanjing was moved due to the construction of the subway and the upgrading of the transportation system.The reason for this was a disjunction between the superior planning of the urban spatial development and the construction of urban sculptures, which cannot meet the long-term and short-term goals of urban development.

•
Non-standard management system.Urban sculpture construction is based mainly on local management and lacks overall city coordination.The management levels of different districts are uneven and the division of responsibilities are not clear, as they lack unified mechanisms throughout the entire process of production.Many cities do not have a specific department to manage the construction of sculptures.Therefore, the construction of sculptures cannot be combined with several major projects in urban transformation, such as the regeneration of historical and cultural blocks.Contrary to the principle of intergenerational equilibrium, the spontaneous construction of sculptures in the short-term will lead to overdevelopment.Construction should satisfy the long-, medium-, and short-term goals, and be carried out in a planned and regulated manner [67].In some cities, urban sculptures are often monopolized by a small number of governors and elites, meaning that the citizens cannot participate in the process, which goes against the principle of people-orientation [68,69].
In response to these issues, urban sculpture planning has been utilized as a tool of solution by several cities in China.It has been suggested that the drafting of the urban sculpture development plan should be gradually transferred to regional coordination, location confirmation, measurement control, and cultural guidance in the long run.Through these methods, Chinese urban sculptures will be pushed towards the path of sustainability.Furthermore, it has been proven that urban sculpture will become an indispensable part of the process of urban and social development in China [65].

Drafting Strategies for Urban Sculpture Planning from the Perspective of Sustainability
Although urban sculpture planning of each city has different focuses and methods in each city, it can be summarized and divided into four main aspects.Four strategies compose a theoretical framework of urban sculpture planning, which addresses the four issues in relation to sustainability (see Part 3).According to the analysis, this section proposes advices and guidelines for future planning, using excellent examples in practice and research.

Structure and Image
The Chinese urban sculptural planning system does not just focus on a single urban sculpture, but on urban sculptures as a narrative system of symbols.It emphasizes the distribution structure among the sculpture clusters from the overall city level.The development of urban sculptures has infiltrated into various spaces of the city, as they are inextricably linked to urban transportation, green space systems, and other types of open spaces.This means that determining the spatial planning for the distribution of priority urban sculptures should be based on a comprehensive analysis of other existing urban planning systems.Urban sculpture planning in China's urban planning system usually includes: General urban planning, general urban design, green space system planning, and historical and cultural city preservation planning, etc. Taking Wuhan as an example, GIS (Geographic Information System) technology was utilized in the plan to sort out the spatial distribution structure of urban sculptures [70].The road skeleton, urban landscape system, and urban green infrastructure, etc. were all superimposed to form the elements of an urban public space.Consequently, the overall structure of urban sculpture planning was formed by this open spatial structure.
The interactive relationship between urban sculptures and urban spaces can help to enhance the overall image of the city [20,71].Kevin Lynch's theory of urban images presents five elements that people perceive as urban images: The path, the edge, the district, the node, and the landmark [72].This theory was imported as guidelines for the formation of an overall image of urban sculptures in several cities in China.It has been considered that, if urban sculptures could be linked to these elements, the effects of promoting the city's image and people's perceptions could be enhanced dramatically.In other words, urban spaces that consider these five elements when building sculptures could create the highlights of the overall municipal layout.This cognitive theory and urban landscape system elements are the main basis of hierarchical positioning in urban public spaces from different levels of districts, corridors, landmarks, and nodes [73].The famous international example of this is the 'Angel of the North' landmark, which plays an important role in changing the image of a "postindustrial" city into a "cultural" city [19].The other example can be also seen in Cardiff, Atlanta, Reston, Santa Rosa, and Greeley, where their master plans recommend that public arts should be displayed in the sites corresponding to these five cognitive elements: "Path" of primary road, pedestrian, cycle networks, river, and rail corridors; "edge" of gateways; "district" of parks, education area; "node" of metro stations, town center, and government center; and also "landmarks".[45,[74][75][76][77]. Nanjing, Suzhou, Mianyang, and Wuxi all utilized Kevin Lynch's five elements of perception to form main cognitive systems and they also took the traditional axis of Chinese landscape into consideration [78].Spatial cognitive systems could help to construct an overall visual perception hierarchy of urban sculptures [78].Harbin also considers these five elements, as they create a park and a large square as a core point, urban streets as links, and a general spatial layout of urban sculptures that is based on courtyards, street gardens, small gardens, city entrances, and important road intersections [79].It can be seen that the core areas are composed of elements that include points, lines, and faces, as they are the guiding core points of urban space imagery that correspond to the five elements proposed by Kevin Lynch.
The above-mentioned structure and image formation should be based on a full understanding of the status quo of sculpture, the urban natural environment, and the humanistic environment.The preliminary work for the preparation of urban sculpture planning includes a basic survey of the distribution of current urban sculptures, specific themes, and features.Taking Nanjing as an example, a master distribution plan was made by locating current urban sculptures on the map and other analysis, such as themes' classification, was also formulated according to the investigation data.(Figure 2) A database of urban sculptures was also formulated using GIS technology.Standardized charts of urban sculpture survey included basic information, such as individual sculptures, photographs, designers, and other basic information.This information can be utilized to analyze different themes or districts of current urban sculptures systematically."The urban sculpture current situation survey fully investigates and analyzes the status quo of urban sculpture and provides valuable digital basic data for the systematic management of urban sculptures.In the future, this information can also be reflected in the urban tourism systems" (Interviews with Wang Zhaozhao who is in charge of urban sculpture construction at the Nanjing Urban Planning Bureau, March 2017).The direction of priorities for future development can be determined by comparing the current distribution density of urban sculptures with the planned structure and image, which can be determined by analysis of existing planning documents.Unsustainable issues of excessive concentration and duplication of themes in the process of urban sculpture development can be avoided from a macro level.Taking Shanghai as an example, the "Shanghai Urban Sculpture Master Plan" was compiled under the framework of the "Shanghai Master Plan".It takes urban public spaces within the administrative jurisdiction of Shanghai as the main planning scope.The plan determines the layout of key districts for urban sculptures from two different geographic levels of the city level (shiyu) and central city-level (zhongxin cheng).The city level determines the urban development structural axis, key urban areas, and industrial districts in the suburbs, and the key areas for the construction of urban sculptures; the level of central urban area determines the geometric patterns of 'one vertical, two horizontal, three rings, many hearts' (yizong, liangheng, sanhuan, duoxin).(Figure 3)."One vertical" represents the Huangpu riverside landscape axis; "two horizontal" means the Suzhou riverside landscape axis and the avenue from the east to the west; "third rings" Taking Shanghai as an example, the "Shanghai Urban Sculpture Master Plan" was compiled under the framework of the "Shanghai Master Plan".It takes urban public spaces within the administrative jurisdiction of Shanghai as the main planning scope.The plan determines the layout of key districts for urban sculptures from two different geographic levels of the city level (shiyu) and central city-level (zhongxin cheng).The city level determines the urban development structural axis, key urban areas, and industrial districts in the suburbs, and the key areas for the construction of urban sculptures; the level of central urban area determines the geometric patterns of 'one vertical, two horizontal, three rings, many hearts' (yizong, liangheng, sanhuan, duoxin).(Figure 3)."One vertical" represents the Huangpu riverside landscape axis; "two horizontal" means the Suzhou riverside landscape axis and the avenue from the east to the west; "third rings" are the inner ring, central ring, and the outer ring landscape axis; "many hearts" determine the business district, the municipal and sub-municipal business centers, historical and cultural areas, large-scale ecological green space, and other key areas as important districts of the sculpture landscape system [81]."From the level of overall planning, urban sculpture planning does not only help to determine the layout of urban sculptures scientifically through sorting out urban spaces in other urban planning systems, but also make sculptures a holistic narrative expression for specific city.At this point the city sculpture was successful" (Interview with deputy chief officers at the Nanjing Urban Planning Bureau, 2017).
business district, the municipal and sub-municipal business centers, historical and cultural areas, large-scale ecological green space, and other key areas as important districts of the sculpture landscape system [81]."From the level of overall planning, urban sculpture planning does not only help to determine the layout of urban sculptures scientifically through sorting out urban spaces in other urban planning systems, but also make sculptures a holistic narrative expression for specific city.At this point the city sculpture was successful" (Interview with deputy chief officers at the Nanjing Urban Planning Bureau, 2017).

Identity and Heritage
As illustrated by TC Chang, "contemporary public art has the power to inform place identity" [40]."Identity in this context is a socio-spatial concept in that people themselves endow places with meaning, leading to identification with shared characteristics between groups within locality" [20].Good urban sculptures can form a special "sense of place" by shaping regional culture [82], creating a cultural landscape, and inheriting the collective memory of the city [83], so as to give its residents or tourists a sense of identity.This is largely due to the local cultural information displayed in urban sculpture and the high degree of conformity between urban sculpture and the local environment.As suggested by Tim Hall and Iain Robertson, two elements

Identity and Heritage
As illustrated by TC Chang, "contemporary public art has the power to inform place identity" [40]."Identity in this context is a socio-spatial concept in that people themselves endow places with meaning, leading to identification with shared characteristics between groups within locality" [20].Good urban sculptures can form a special "sense of place" by shaping regional culture [82], creating a cultural landscape, and inheriting the collective memory of the city [83], so as to give its residents or tourists a sense of identity.This is largely due to the local cultural information displayed in urban sculpture and the high degree of conformity between urban sculpture and the local environment.As suggested by Tim Hall and Iain Robertson, two elements are crucial to develop a sense of place through urban sculptures: The creation of artwork unique to sites, and the development of an awareness of the tradition and identity that is unique to a certain place [84].The corresponding planning strategies of urban sculptures are mainly represented in the selection of the theme of the urban sculptures, based on both the regional cultural resources and the selection of the location, which often relates to historical events [37].The construction of urban cultural landscapes and collective memories plays an important role in the transmission of urban historical culture through full use of urban history, city characteristics, and regional culture.Taking the urban sculpture planning of Xi'an as an example, a large amount of data was collected on historical contexts in the early stages of the planning work, including key historical figures, events, and the locations of historical events, and 116 typical historical subjects and events were selected.According to the time of the historical events, such as dynasties, the sculptures were arranged to form an "oriental city sculpture poem" of historical local characteristics [85]."Manchester's Northern Quarter Public Art Scheme" is an international example of the adoption of this approach of reflecting the local identity through a study of local history on Tib Street [20].Other famous examples can also be seen in Virginia [86] and the "Power of Place" projects in Los Angeles [87].The layout of urban sculptures in Xiangtan city took full account of the location of major historical events, trying to awaken people's memories and innermost feeling to carry forward this traditional history and culture.The planning process considered historical events, historical and cultural blocks (lishiwenhua jiequ), famous monuments, and celebrity relics as the main distribution focuses of urban sculptures.This analysis was mainly based on the historical and cultural city's planning documents of conservation.Several locations were selected, such as the Guandi Temple, Martyrs, and celebrities' former residences [88].
In addition, urban sculpture planning should also play an important role in the protection of urban heritage, which includes both physical and metaphysical aspects.This does not only mean the protection of existing heritage sculptures, it also means that urban sculptures could be used to rejuvenate historic districts and cultural blocks, by highlighting the history and heritage of a place [88,89].McCarthy argues that "the use of historical associations can provide a valuable means of linking public art with local identity" [20].In China, the construction of urban sculpture is usually incorporated into the regeneration of the historical and cultural blocks.For example, the Luwan District of Shanghai is rich in historical resources.Nearly one-quarter of the district has been categorized as a historic conservation area.During the planning process of urban sculptures, these resources are considered.Intangible historical and cultural resources are materialized in the form of sculptures by an emphasis on themes, such as historical events, folk culture, historical figures, literary arts, and historical buildings, for future developments.These main themes were formulated by examining important historical events, historical figures, and cultural relics of historic buildings [90].Harbin has proposed to place sculptures at the historic sites, such as the locations of historical events, and places where outstanding historical figures lived and worked [79].In the process of the renewal of historic districts, the important role of public art has been examined by several researchers, such as Beijing's 798 Historic District [3] and Shanghai's Red Town Urban Regeneration project [91].Urban sculpture planning puts these kinds of projects on the agenda.A "culture-led" approach to regeneration and the mechanisms of its application are embedded in the regeneration policies and practices in UK, such as the famous example of the Tate Modern in London.This can also be seen in the Guggenheim in Bilbao [20].It can be said that, especially in the post-industrial era, urban sculptures can help realize the transformation and revitalization of cultural centers from global experiences.However, one critical issue of equity should be recognized, as the public art could lead to gentrification in some circumstances.In addition, some researchers point out that the simple historical reflection may only lead to "nostalgia and the re-production of myths" [19,20].
In Chinese urban sculpture planning systems, the urban sculptures are actively advocated to be utilized to activate the historic street renewal project, inherit the historical context, and construct a tangible spatial form [64].Many Chinese cities attempt to create more sculptures with themes of regional culture and historical information in sculpture planning.This also encourages a variety of sculptures to be built at the same time.Urban sculptures also provide a platform for sustainable education, presenting a unique form and interface for the continuation of ecological concepts.Through the experience of the sculpture, sustainable environmental ethics and the educational function of sustainable development can be realized [37].Since Harbin is building an ecological city, the planning of the sculpture emphasizes the construction of related themes, such as ecological conservation [79].

Space and Function
One way of using art in urban sustainable development is realized through an interaction with the environment [17], "Public art may be defined as site-specific art in the public domain" [20].Kwon has analyzed the specific form of site-specific public art, emphasizing the important connections between sculpture and the environment [92].These interactions between urban sculptures and the environment have manifested itself in several ways.First of all, the urban sculptures should be environmentally friendly and fit with the natural environment [66].When the environment surrounding the urban sculpture project changes, the main structure of the original urban sculpture project should be tested and reinforced if necessary.In addition, urban sculptures should utilize their tangible forms to emphasize the surrounding environment, working together with the surrounding environment to enhance the quality of the space.
Interpreting the correlation and mutual restraint between urban sculptures and urban space on an artistic level can be regarded as urban sculpture planning's main basis for consideration.In other words, urban spaces with different locations, functions, history, and forms restrict the selection of specific attributes and the spiritual implications of the urban sculptures.Most plans guide the corresponding theme and specific attributes of urban sculpture according to the nature of the area.The planning of the urban sculptures ensures that the artistic life of urban sculptures is long-lasting, and the dynamic urban development, such as the nature of the land use, corresponds to the urban sculptures.Therefore, it is necessary to analyze the public spaces that may be associated with the urban sculptures and try to determine highly relevant urban spaces.By classifying these typical urban spaces, the corresponding principles of urban sculpture guidance are proposed in urban planning documents.Taking Tianjin as an example, typical urban spaces are divided into seven different types of spaces: Urban plazas and parks, residential areas, research and education spaces, culture and medical facilities, large commercial areas, and transportation stations [93].For these different types of areas, corresponding guidelines for urban sculptures were put forward, including indicators, themes, size, form, material, color, and other elements.It is worth mentioning that Tianjin was the first city to put forward the specific indicator for urban sculptures in relation to its population.It is conceptualized that, until 2030, the number of sculptures will be no less than one piece per 10,000 citizens within the city boundary, and two pieces per 10,000 citizens within the central city area.This can also be seen in the "Public Art Master Plan of Fort Worth", in which it is suggested that public art should be integrated with the development of special spatial functions of the regional transit system that connects the growth centers and villages along commercial corridors [47].
Taking "urban sculpture planning in the central city of Beijing" (Beijing zhongxincheng chengshi diaosu guihua) as an example (Figure 4), it has defined a total of 125 key districts for the future construction of urban sculptures [94].These districts are divided into six types based on their different functions: Historical conservation areas, large urban functional areas, urban special cultural areas, and centralized parks, green lands, strip green areas and waterfront, and urban road interfaces.Focusing on the cultural features and functional attributes of the key districts, the theme of the corresponding proposed urban sculpture was matched.The plan sets the requirements for urban sculptures in the form of detailed drawing guidance for different land functions.At the same time, there is moderate degree of flexibility to consider more detailed contents, such as the location, scale, and material of urban sculptures, in conjunction with the urban design of the region in the next step, and proposes more detailed guidelines for the design of urban sculptures at the site level as an artist's urban sculpture task manual.It also recommends that urban sculpture planning should be incorporated into the detailed guidelines for urban design, the implementation phases of key planning, and development initiatives.In this plan, it fully relies on the relevant contents of the central city control regulations and urban design guidelines to ensure the unity of planning [95].Urban sculpture planning is integrated into the entire system of urban planning [66].

Coordination and Management
To ensure the implementation and management of urban sculpture planning, it is necessary to improve local policies, detailed rules of implementation, and corresponding operational mechanisms.The coordination function of the urban sculpture management system mainly includes the systematic design of specific implementation links, participating entities, fundraising, near-long-term planning, hierarchical divisions, and legislative trials.Urban sculpture construction management systems integrate the planning, selection, approval, construction, evaluation, conservation, and maintenance of the urban sculptures into a complete system [69].In particular, different participators of the creative subject (artist and sculptor), the evaluation subject (evaluation commission composed of experts, scholars, and citizens), and the promotion subject (related government department) are integrated and managed by the system during the construction process [96].The current mechanisms for the production in China is mainly influenced by the government, while community-led sculptures and urban sculptures promoted by non-government agencies are rare.Most urban sculptures are still influenced mainly by the opinions of the government and elite groups.Therefore, it is necessary to focus on developing a reasonable mechanism for public participation [55].At the same time, multichannel financing methods suitable for local administration should be explored, such as setting up public art funds, special funds for key projects, and private investments.Urban sculpture

Coordination and Management
To ensure the implementation and management of urban sculpture planning, it is necessary to improve local policies, detailed rules of implementation, and corresponding operational mechanisms.The coordination function of the urban sculpture management system mainly includes the systematic design of specific implementation links, participating entities, fundraising, near-long-term planning, hierarchical divisions, and legislative trials.Urban sculpture construction management systems integrate the planning, selection, approval, construction, evaluation, conservation, and maintenance of the urban sculptures into a complete system [69].In particular, different participators of the creative subject (artist and sculptor), the evaluation subject (evaluation commission composed of experts, scholars, and citizens), and the promotion subject (related government department) are integrated and managed by the system during the construction process [96].The current mechanisms for the production in China is mainly influenced by the government, while community-led sculptures and urban sculptures promoted by non-government agencies are rare.Most urban sculptures are still influenced mainly by the opinions of the government and elite groups.Therefore, it is necessary to focus on developing a reasonable mechanism for public participation [55].At the same time, multi-channel financing methods suitable for local administration should be explored, such as setting up public art funds, special funds for key projects, and private investments.Urban sculpture planning should be set up in a step-by-step, orderly, and reasonable way, in order to guide the cities' recent and long-term urban sculpture construction [97].In the plan of Taizhou, different description methods were used to determine the relevant contents of the short-, middle-, and long-term sculpture planning projects.The short-term planning is relatively microscopic, focusing at the local sculpture placement, theme selection, and the guidance of related attributes and indicators.Long-term planning puts forward different requirements for key areas, such as commercial areas and residential areas, and takes principled guidance with regards to the main methods, referring to the description methods of the city's overall planning and sub-district planning [62].The management system should also combine legislation and regulations into the production of urban sculptures.The specific provision of the "Zhengzhou City Sculpture Management Measures" was set up according to the "People's Republic of China Urban and Rural Planning Law", "Copyright Law of the People's Republic of China", "Urban Design Management Measures", and other laws and regulations.The Yangpu District of Shanghai has tried to incorporate urban sculpture into the conditions of urban land transfer [98].While ensuring the implementation of urban sculptures, this also provides a basis for subsequent planning management.
The development of urban sculptures should meet the requirements of intergenerational balance.Urban sculpture planning should have flexibilities, the ability to look to the future, be open to change, and sustain people's interest in urban sculptures over the decades [99].Greater participation is generally agreed to be one of the central principles of sustainable development [17,100].The initial formulation of urban sculpture planning was a result of the rapid and large-scale development of sculptures by local governments with a conscious promotion of public participation.Permanent offices are responsible for the planning, organization, coordination, and management of the city's urban sculptures.Art committees, which consist of sculptors, planners, architects, landscape architects, sociologists, and other experts, are responsible for the evaluation of the city's major urban sculptures and decision-making process.In this way, the establishment of specialized management institutions for urban sculpture will benefit the participation of all sections of society, which will be advantageous for the daily management of the urban sculptures, and also for the smooth implementation of sculpture planning [55].The case of Manchester is very distinctive in its application of relatively loose, fluid, and flexible processes through innovative participation methods, such as the "Big Jam" open-forum sessions [20].As McCarthy argues, the use of flexible processes are always conflicting with the provision of detailed frameworks and guidance [20] (p.247).Also, "there needs to be a high degree of flexibility within the roles of artists to ensure an innovative and diverse approach" [20].Therefore, sculpture planning should avoid excessive intervention and guidance.

Discussions and Conclusions
Above all, the study has summarized how the existing urban sculpture planning documents in China try to realize sustainability in terms of the framework of systematism, regionalism, integration into the surrounding urban space, and management.The planning documents can be divided into three different levels.The general plan proposes geometric patterns to help to realize the city image and the overall sculpture planning structures based on the legacy of existing sculptures.Sculptures of themes, which could highlight regional culture and history, are recommended in the detailed plans.In the planning, urban sculptures were creatively applied in urban renewal, cultural heritage protection, urban characteristics, and personalized expression.Urban sculptures also promote the sustainable development of urban space and the formation of an urban landscape.The management of urban sculpture planning provides a certain degree of flexibility, leaving space for artists to create, while also trying to build a multidisciplinary integration platform so that different fields of scholars can work together to provide suggestions of sustainable development for urban sculptures.It can be seen that the first three principles are all closely related to the 'co-production of sculptures and cities' [101] (p. 1).In other words, the way that the China's urban planning systems move urban sculptures towards sustainability are operated by and through positive interactions between arts and cities.They discuss the important guiding principles that are useful for the implementation of sculptures, such as the selection of sites and the selection of sculptures.As argued, one of the core principles for sustainability is "quality of life", and urban sculpture planning, as an important part of cultural policy that links art and the environment, can promote the core aim of sustainable urban development [17].The fourth principle of 'coordination and management' can be seen as an institutional guarantee, which could guide the smooth implementation of planning.
This article argues that urban sculpture planning is formed under specific Chinese social structures, the political government, and cultural backgrounds through reviews of the urban sculpture planning development process in China.Some scholars state that urban sculpture planning is used as an instrument to both boost urban entrepreneurialism and advance state authoritarianism in China [49,102].Although urban sculpture planning largely originated from the leadership of local governments, it also involves experts, scholars, and citizens of various professions in its formulation process.Public art was an essential element of the early planning profession in the United States, which can be traced back to the collaboration of Frederick Law Olmsted with artists during the "City Beautiful Movement" [103].This historical echo tells us that the urban sculptures were situated within the planning system globally.It is not just linked to the specific political factors of China.In other words, we argue that the appearance of urban sculpture planning in China is not simply due to the authoritarian mode of state, but the means and methods that are suitable for the sustainable production of urban sculptures and sustainable urban development.The main purpose of the planning is not only for realizing political and social control, but to cope with various problems that have emerged in the rapid development of urban sculpture construction.
Through the analysis of this article, it can be seen that China's urban sculpture planning has several special focuses in relation to sustainability.Firstly, the urban sculpture planning is usually examined from the city scale by incorporating urban sculptures within the framework of the whole urban planning systems and cultural policies in China.Secondly, it is conceptualized to make strategies based on the overall situation of urban sculptures in the city.Moreover, it is also a pioneering attempt to refine the guidance in urban sculptures through their relationships with the dynamic function of land use.These points were all examined specifically in this article through the main cases in Chinese contexts.However, some of China's challenges relating to sustainable development are not unique.For example, since the 1980s, a general consensus has already formed globally that urban regeneration can be realized through the use of public art [12,15,87,88].Therefore, we have also adopted many excellent international examples and theories to help illuminate the conceptual framework of sustainable principles.All in all, although the urban sculpture planning system is formed with the special context of China, several principles towards sustainability are not unique.Thus, the planning principles put forward in this article also offer valuable insights into global issues relating to sculpture sustainability.
However, we must acknowledge that there are still several problems in the urban sculpture planning system.Currently, most of the Chinese urban sculpture plans have been made for upcoming urban sculptures instead of existing sculptures.Therefore, future research is required, in order to evaluate and recycle the existing sculptures [104].We can also see the example of the "IXIA Public Art Think Tank" has conducted a very brief evaluation framework [57].More studies should be carried out to evaluate existing sculptures.This article has taken a glimpse at the effectiveness of the urban sculpture planning through the method of interviews, but a more specific evaluation framework remains to be studied based on the current article.
The value of this exercise is threefold: (1) The study enriches the geographic research of internationalized sustainable public art planning in different regions through studies of the urban sculpture planning under the specific circumstances of China; (2) the notion of sustainable development of urban sculpture was proposed and expanded, especially from the perspective of planning strategies and cultural policies; and (3) in addition, sustainable principals for the development of sculptures in terms of the four aspects of systematism, regionalism, environmentalism, and management were proposed.Our findings enrich valuable knowledge on geographic studies of public art planning through the contextualized analysis of Chinese urban sculpture planning systems.Moreover, results will be valuable to both policy makers and other urban actors of urban planners, artists, and architects in crafting strategies about the sustainable production of urban sculptures through improving planning efforts.Although China's political, social, and economic conditions are unique, it does not only provide experiences for China's urban sculpture production, but also acts as a valuable reference to the development of urban sculptures in other regions and countries.
Author Contributions: Z.L. contributed to the conceptualization of the article and development of the conceptual framework.She also contributed to the collection and analysis of the literature and the manuscript writing.Five windows, two rings and two axes, city square, key section [112] Xianyang -(b) Xianyang Urban Sculpture Planning System Multi-center, five major areas, scattered groups [107]

Figure 2 .
Figure 2. Examples of analysis in the Nanjing sculpture investigation.(a) Distribution of urban sculptures within main urban areas' boundaries and the old city's boundary (a red spot represents one piece of sculpture, about 1,069 pieces in total until 2015).(b) Analysis of sculptures located in 11 different administrative districts.(c) Analysis of different types of sculptures in Nanjing (classified according to investigation).Source: Drawn by the author according to the data from Nanjing Urban Planning Bureau [80].

Figure 2 .
Figure 2. Examples of analysis in the Nanjing sculpture investigation.(a) Distribution of urban sculptures within main urban areas' boundaries and the old city's boundary (a red spot represents one piece of sculpture, about 1,069 pieces in total until 2015); (b) Analysis of sculptures located in 11 different administrative districts; (c) Analysis of different types of sculptures in Nanjing (classified according to investigation).Source: Drawn by the author according to the data from Nanjing Urban Planning Bureau [80].

Figure 3 .
Figure 3. "The configuration of the sculptures in the central city" in the Master Plan of Sculptures in Shanghai, 2006.Source: Shanghai Municipal Planning Bureau [81] (Translated by the author).

Figure 3 .
Figure 3. "The configuration of the sculptures in the central city" in the Master Plan of Sculptures in Shanghai, 2006.Source: Shanghai Municipal Planning Bureau [81] (Translated by the author).

Table 1 .
Products or activities of public arts.

Table 2 .
Keywords for the search in the academic databases.

Table 3 .
Aspects for literature examination.

Table 4 .
Number of sculptures in some Chinese cities.
Source: Drawn by the author according to the data from literature review.

Table 5 .
Influencing factors of urban sculptures in relation to sustainability.
Source: Drawn by the author.