KIEAE Journal

Concerning the system related to multi-dimensional utilization of urban planning facilities in Korea, Article 61, Subparagraph 1 of the National Land Planning And Utilization Act stipulates the basis for determining the spatial extent of urban planning facilities, while Articles 3 and 4 of the Rules on Determination, Structure, and Installation Standards of Urban or Gun Planning Facilities stipulate the basis for duplicate decision and three-dimensional decision of urban planning facilities. In particular, the Seoul Special Metropolitan City, experiencing a growing need for multi-dimensional development for efficient utilization of land, is planning to introduce multi-dimensional utilization of urban planning facilities by establishing standards for overlapping and complexing of urban planning facilities.

In December 2021, the City of Seoul improved the standards for overlapping and complexing of urban planning facilities for efficient utilization of limited urban spaces and reflect the changes in conditions according to time, including the changes in demand of urban planning facilities due to the population and household changes, technological advancements, and increased demands for overlapping and complexing. First, a duplicate decision refers to determining to have two or more urban planning facilities overlap horizontally or vertically on the same land as shown in Fig. 3. Vertical duplicate decision can be applied to all facilities, whereas horizontal duplicate decision is limited by the facility depending on the allowable extent through which matrixing the facilities that are overlapped with existing facilities. Three-dimensional decision refers to determining only a part of the space where urban planning facilities being developed are located, which is allowed for all facilities excluding gas supply facilities, cremation facilities, and waste treatment facilities that may have a hazardous impact on general buildings in a neighborhood including parks, elementary, middle, and high schools, and universities. Spatial extent refers to determining a certain spatial extent of existing urban planning facilities for allowing buildings or structures that are not urban planning facilities on the land that has been dedicated to urban planning facilities; operational standards are applied according to interoperability, physical installation feasibility, and spatial availability among facilities. However, unacceptable facilities include parks, plazas, reservoirs, schools, general medical facilities, rivers, and waste treatment facilities[11]. The standards for overlapping and complexing of urban planning facilities specify duplication decision, three-dimensional decision, and determination of spatial extent. However, parks and green spaces related to multi-dimensional city parks are not allowed in the determination of spatial extent; therefore, there remain institutional limitations in the formation of three-dimensional urban parks.

Fig. 3. 
Standards for overlapping and complexing of urban planning facilities (Source: [11], Edit by Author)

Urban planning facilities increased in number by concentrating on quantitative supply in the past; however, currently, there is a growing need for finding sustainable development directions in the transition period fueled by aging population, infectious diseases, and technological advancements. In line with periodic changes accelerated by technological development, multi-dimensionalization and functional advancements of facilities are needed to meet the demands for various facilities and ensure efficient utilization of limited land resources, considering the changes in type, form, and location of urban planning facilities. Accordingly, various complex projects have been carried out recently as shown in Fig. 4. However, improvements have been consistently proposed because the standards contradicted the existing standards. First, the approval for the Sinnae 4 public housing district was announced in June 2021 based on the decision for multi-dimensionalization of roads and parks; however, parks are designated as unacceptable facilities, thus contradicting the existing standards. In terms of the Jangji garage, B1F - 2F were set as parking lots, while the fourth floor was considered to be designed as a green space; however, parks are unacceptable facilities according to the determination of spatial extent. For the Guui reservoir, determination of spatial extent was announced in December 2015 to introduce happy housing at the upper part; however, the existing standards prohibited a reservoir from being the subject of determination of spatial extent, thus, requiring improvements as well.

Fig. 4. 
Case of three-dimensional complex plan (Source: [11])

The three-dimensional urban planning system of Japan specifies the necessary scope for maintaining urban planning facilities, such as roads, rivers, and parks, thus, bypassing the limitations on construction stipulated in Article 53 of the Urban Planning Act within regarding urban planning facilities. However, the three-dimensional urban planning system is not coordinated with the Building Standard Act of Japan, thus, it is not regulated considering the mitigation of the limitations on construction regarding urban planning facilities, such as roads and parks. Therefore, construction cannot be carried out by mitigating the limitations on construction of the Building Standard Act only through the three-dimensional urban planning system. Consequently, multi-dimensional utilization is promoted through multi-dimensional road or city park systems for complex developments utilizing urban planning facilities, such as roads and parks[12].

The three-dimensional city park system implemented in Japan was first established through the revision of the Urban Park Act in 2004 for efficient maintenance of urban parks, promotion of complex space utilization along with other facilities, mitigating the urban thermal island phenomena, and recognizing the need for parks that provide a relaxed environment for people. According to Article 20 of the Urban Park Act, a park manager must determine a multi-dimensional city park region if deemed necessary to promote appropriate and reasonable land use, considering the situation of the region where city parks exist. The target facilities include underground spaces of existing city parks, building rooftops, upper parts of artificial grounds, as well as existing and newly constructed parks; the installation condition specifies that parks should be easily accessible on foot by general users. In particular, if parks are installed on the rooftop of commercial and business facilities, opening hours are set to be within a range that does not cause inconvenience for general users. As shown in Fig. 5., ample resources and technological expertise of private entities can be sufficiently utilized because integrated maintenance of city parks and private facilities are feasible.

Fig. 5. 
Three-dimensional city park system in Japan (Source: [12], Edit by Author)

When a three-dimensional city park is installed on building rooftop, any problems with the building structure may also affect the three-dimensional city park. Therefore, to secure the perpetuity of a three-dimensional city park, which is a public facility, regardless of the intention of a building owner, there is an integrated park building system where a park manager and building owner agree on proper building management tasks including the burden of expenses[12].

The Americasan Park was the first park developed by applying the Japanese three-dimensional city park system in 2009. Two regions nearby the park, Motomachi and Yamate Districts, are well-known tourist spots in Yokohama; however, improvements are required with respect to accessibility of pedestrians between the two districts which have 18-m difference in altitude. As shown in Fig. 7., the Motomachi/China Town Station of the Minatomirai Line in the Motomachi District, which is located at the bottom of the slope, will be extended and altered from the second to the fourth floor to create a park area. The green spaces in the Yamate District located at the top of the slope will be modified thoroughly to provide easy accessibility from the Motomachi to Yamate District[17]. Moreover, as shown in Fig. 8., the third and fourth floors and the rooftop of the railway station located in a private land are owned by the city of Yokohama; thus, a rooftop garden was installed in addition to stairs, escalator, and elevator to improve users’ accessibility and convenience. From the management perspective, convenience and park facilities are managed together leveraging on the resources and technological expertise of private businesses.

Fig. 7. 
Layout and bird’s eye view (Source: [18], Edit by Author)

Fig. 8. 
Park management (Source: [22], Edit by Author)

The cross-sectional image of the Americasan Park before and after the development depicted in Fig. 9. indicates that the number of entrances increased. Accordingly, the building has been integrated with the railway station within the park using the stepped land, and the city park is established at the upper part of the building. As shown in Fig. 10., facilities are installed in lower and upper levels, and the two-story building before the development has been expanded to a four-story building after the development.

Fig. 9. 
Sectional change due to the development (Edit by Author)

Fig. 10. 
Changes before and after the development (Source: [18])

As part of the integrated Tokyo Metropolis downtown redevelopment project carried out along with village formation, the park was created by applying the three-dimensional city park system to the upper part at the junction of the Shuto Expressway. At the downtown center, in which various infrastructures are concentrated on a limited land, the park was created by applying multi-dimensional and multi-layer integration with other buildings. Expressways, two redeveloped buildings, and parks are all located within a redevelopment area of 38,000㎡. From the perspective of village formation in Japan, residential houses and commercial facilities, such as public libraries, have been established in a balance in the form of a compact city in two redevelopment buildings, namely, the 27-story Prism Tower and 42-story Cross Air Tower constructed by Tokyo Metropolis.

In particular, the upper part of the expressway junction is formed as a park by applying the multi-dimensional road and park systems; on the rooftop of the expressway junction located approximately 7–35m high from the ground , the Meguro Park was created based on the sky garden concept on the site of 7,000㎡. As shown in Figs. 12., 13., and 14., this park is accessible from the fifth floor of the Prism Tower and the ninth floor of the Cross Air Tower, or through a pedestrian bridge called Opas Bridge and elevator from the Opas Yumehiroba Square. Inside the junction roof, a multi-purpose square called Opas Yumehiroba Square is formed on the site of 3,000㎡, in which various meeting, sports, and recreation activities take place. This structure has been contributing significantly to the regional vitalization with high utilization rate and satisfaction level among residents along with the Meguro Tenku Park.

Fig. 11. 
Park view (Source: [19])

Fig. 12. 
Sectional change due to the development (Source: [20], Edit by Author)

Fig. 13. 
Changes before and after the development (Source: [21])

Fig. 14. 
Access route to the park (Source: [21], Edit by Author)

As part of the administrative policy of local governments to expand green spaces and nursery facilities, the park is located on the rooftop as a complex facility formed to integrate park and nursery facilities by utilizing the three-dimensional city park system. Public restrooms are available on the first floor for 24 h, and a wastewater reservoir is created in the first basement floor in case of emergency. The rooftop park consists of a natural lawn square, playground, and relaxation area for residents as shown in Fig. 15. When the cross-sectional image of the Mizutanibashi park before and after the development depicted in Fig. 16. is analyzed, the number of entrances has been increased according to multi-dimensional utilization of the facility. The park used to be directly accessible from the ground level before the development but stairs and elevators have been installed after the development to provide access to the rooftop park because nursery facilities were installed in lower floors of the building. The facilities at the bottom of the park were established to satisfy the needs of the local government.

Fig. 15. 
Rooftop park view (Source: [23])

Fig. 16. 
Sectional change due to the development (Edit by Author)

As shown in Fig. 17., commercial facilities and hotels are added to the existing municipal Miyashita Park and parking lots. This particular case involves revamping the Miyashita Park into a safer and more pleasant environment to maximize the charms of urban parks throughout the facility, thus adding value to the district.

Fig. 17. 
Three-dimensional park view (Source: Nakasa & Partners, Japan)

A private contractor was selected for the Miyashita Park development project in August 2014 who had to proceed with the development project to create a three-dimensional city park by considering the following tasks: improving the seismic performance to prevent possible damage being inflicted on the crossing bridge during disasters, tree collapsing due to strong wind, securing a barrier-free circulation path when using the facility, and heightening the pedestrian convenience at the Shibuya Station in the case of increased number of users. From the perspective of local governments, the Miyashita Park development project required strengthening of a green base through flexible park usage, creation of a prosper base, formation of a pedestrian network hub, complexing of functions accepting culture, enhancement of disaster prevention function linked with regions, and highly convenient parking lots. The number of facilities in the lower part of the park increased, where the first floor was designated as a parking lot and space above was designated as the municipal park. After the development, commercial facilities of small-scale shops are additionally established up to the third floor.

Analyzing the cross-sectional image of the Miyashita Park before and after the development depicted in Fig. 18., observe that the number of entrances has increased after the development by utilizing the land characteristics. Furthermore, nodes facilitating the new pedestrian networks were created as shown in Fig. 19. through which the accessibility from the Shibuya Station was improved. Facilities are located below the park, which is constructed on the rooftop. The park formation includes the roads, which were divided into two parts vertically and have been unified through the multi-dimensional use of altitude difference of the land. A designated manager system was adopted in the Shibuya ward where Miyashita Park Partners consisting of the Mitsui Fudosan Co., Ltd. and Seibu Landscape Co., Ltd. were chosen as a designated manager in December 2019. Comprehensive management by the designated manager, including maintenance of green spaces and facilities, event planning, and attraction, has been providing a safe park environment while creating vitalized urban spaces.

Fig. 18. 
Sectional change due to the development (Edit by Author)

Fig. 19. 
Access route to the park (Source: [24], Edit by Author)