Award-winning project Seoul Urban Renewal: Cheonggyecheon Stream Restoration

Seoul , South Korea

In 2005, Cheonggyecheon Stream has been transformed into a 10.9 km (7.0 miles) long, modern public recreation space in downtown Seoul.

The area was once the center of urban economy as one of the most vibrant business districts in the capital area. The elevated highway covering the stream acted as an artery of transport and logistics. However, as time went one, the overpass had deteriorated to raise many safety issues not mention to the disfiguration. Additionally, the need was ever- growing for an eco-friendly urban renewal to keep up with social changes such as shifting economic focus and residential pattern.

Against the backdrop, the Seoul Metropolitan Government undertook the massive urban renewal project including the restoration of the stream. The aim of the project was to restore a decrepit public space to create a waterfront in the downtown, improve the environment and restore the historical value. Such an attempt would revitalize the city by attracting more population and more business activities, which would eventually enhance growth momentum and attract more private investment. At the same time, the discussions included the measure through which the private and public sectors could share the benefit, while achieving urban revitalization led by the private sector. Along with setting the long-term goal, determining specific project boundary was another challenge.

Despite fierce criticism and skeptism in the first place, it is now considered highly successful, strengthening the resilience of eco-system and providing a resting, green space for the citizens.

Award-winning project

This project was awarded the 'Sustainable Transport Award' in 2006. Learn more about the award.


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City information
City
Seoul

Size and population development
2011: 9,736,000; 1990: 10,544,000; 2025: 9,867,000; 2010-2015: -0.02% / year

Population composition
declining population due to high living costs and aging population; religions: Christianity and Buddhism

Main functions
Capital City, national and international economic hub

Main industries / business
finance, IT and electronics, food and beverages

Administrative structure
25 districts ("gu"), 423 neighbourhoods ("dong"), 13,787 "tong", 102,796 "ban"

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Background and objectives
  • Safety issue of the elevated highway

It was the safety issue that triggered discussions on the restoration of Cheonggyecheon. The structure of covering road and the elevated highway was deteriorated, causing serious safety risk since the 1990s. As an in-depth investigation conducted by the Korean Society of Civil Engineers in 1991-92 found the corrosion of the steel frame inside the highway and structural flaws in its upper plate, a thorough repair work was conducted for a 2-kilometer sector of it. The 30-year-old road covering Cheonggyecheon costed substantial amount of money for continuing maintenance and repair. Another in-depth safety checkup conducted from August 2000 to May 2001 revealed that cracks and exfoliation persisted in the upper slab, while the load carrying capacity was insufficient due to the worn-out concrete beams. As a result, a full-scale reconstruction was inevitable. Reconstruction was estimated to cost 93 billion won in three years. In 2001, the city government of Seoul planned to demolish the elevated highway and reconstruct it, beginning from August 2002. 

  • Shift from maintaining the elevated highway to restoring the stream

Since the 1960s, development, construction, production and efficiency have always been priorities in Seoul. Starting from 1990s, however, the urban planning paradigm shifted to focus more on human, history, nature and environment, as the people's consciousness changed over the course of socio-economic development. Discussions on justification, necessity and significance of restoring Cheonggyechon became lively since the late 1990s. The restoration became a major topic during the mayoral election campaign in the first half of 2002. Over the course of political debate, the direction of initial plan shifted from reconstruction of the elevated highway to restoration of the stream. There were still many choices and decisions to make between the idealistic goals―historical values, eco-friendliness, optimization in each sector, etc.―and the practical considerations―cost, time, optimization in the entirety, minimization of inconvenience among the neighboring businesses, phased approach, etc.

  • Public-private partnership issue

While Cheonggyecheon itself was a public place, the surrounding area was privately owned properties. To include the private properties in the project would not only cause the project budget to snowball, but require enormous time to deal with administrative matters such as revision of urban plans and compensation. Therefore, the Seoul municipality decided that the restoration work itself would exclusively cover the public land within Cheonggyero to ensure the feasibility of the project. In this approach, the public and private sectors had to take their respective role in turn. Firstly, the city government was to demolish the coverage and the elevated highway, create an eco-friendly waterfront and restore the historical value of the stream through public investment. The ripple effect of restoration would help revitalization of the downtown and the neighboring area, which will be conducted in partnership with the private sector in a way that both public and private sectors could benefit.

Implementation

Major components of Cheonggyecheon restoration plan

The restoration had to consider diverse factors of Cheonggyecheon in the historical, structural and functional aspects. Restoration of historical remains such as old bridges and stoneworks at the stream was one of the main concerns by citizens. The restored stream also needed to have enough capacity to deal with floods, as abnormal rain fall became more frequent due to climate change. In addition, it was necessary to maintain its previous role for transportation and sewage. Most of all, the project had to create a better natural environment, which was the biggest aspiration of the citizens. To this end, it was imperative to secure water supply for the stream, which turned out a difficult task.

  • Restoration of historical values

Restoration of historical values was important in justifying the project and ensuring citizens' support. With this recognition, the Seoul municipality set it a principle to preserve all the heritage excavated during the construction. In the actual work, however, the safety of citizens emerged as a bigger priority. The municipality's principle was to restore the originality to the extent in which citizens' safety from flood and other risks is ensured. However, some members of the citizens' committee and some civil associations insisted that the stream be restored entirely in its originality. Such a difference sharpened in the phase of actual work. As specific concerns emerged with regard to flood control, transportation and negotiations with the neighbor businesses, some of them became incompatible with the preservation of historical remains.One of the biggest issues was the restoration of Gwangtonggyo bridge. There was a strong argument to restore it to its original shape, which required an extensive work. In order to secure enough cross-sectional area for the water flow, in other words discharge area, it was necessary to purchase private lands in the bridge's vicinity, but it was practically impossible. Insufficient area for discharge would lead to failure in safety and flood control. The city finally decided to rebuild Gwangtonggyo at a spot 150m away from the original location to the upstream, in a belief that restoration at the original location will be possible in the future when a better condition is prepared. Restoration of Supyogyo in its originality might incur similar problems. The Cultural Heritage Committee of Seoul concluded to leave Supyogyo where it was, in the Jangchungdan Park, in order to avoid deterioration of the original stones. At 27.5m, the original Supyogyo was longer than the width of the restored stream (22m) at the point. To restore it in the original shape, the city had to expropriate private properties in the vicinity, which would inevitably prolong the construction and cause more inconvenience for the neighboring businesses. Therefore, the municipality decided to restore Supyogyo in the future, once favorable conditions are made available. See attached fig.

  • Flood prevention and safety measures

Although the restoration of Cheonggyecheon was initiated in a bid to restore historical and environmental values, the safety issues including flood prevention came to the fore in the course materialization. The city set the target flood recurrence interval of 200 years. Given that other 2nd-grade local streams were managed based on 50-year interval assumption, it was a decision to better ensure the citizens' safety by securing sufficient stream capacity to deal with local torrential rainfalls. The city also strived to secure discharge area by excavating the underneath of both banks (see attached fig.).

  • Sewerage treatment

Substantial number of sewerage pipes were buried near Cheonggyecheon, since sewage water of the downtown Seoul was traditionally gathered along it. Finding ways to treat such sewage was a precondition to the restoration. Since the existing sewerage system was often combined with rainwater collection system before it reached the stream, it was practically impossible to segregate sewage from rainwater. Separation between them was also inappropriate because the downtown rainwater flowing into Cheonggyecheon was highly polluted. Therefore, the municipality adopted a double-box system. The sewage would be treated in a combined system, but highly-polluted initial rainfall would be segregated into a separate pipeline to be treated at the treatment facilities, not flowing into the stream (see attached fig.).

  • Water supply and its quality

Cheonggyecheon was historically a ephemeral stream. It was difficult to draw water from the vicinity, because underground water level became lower due to urbanization. Given that there was no valley water from the upstream, artificial supply of water was inevitable to maintain the stream. The Hangang (Han River) and the groundwater discharged from nearby subway stations were selected as water sources. The Korea Water Resources Corporation attempted to tax the Seoul municipality for drawing water from Hangang, but it was eventually discounted by 100% on the ground that the water would be used for the public interest. As for the water quality, the water treatment was decided as secondary treatment considering relevant conditions and costs.

Financing and resources

Budget estimation and its financing were important issues in the project. As the city aimed to have the project recognized as a public one and secure the government budget, it was important to get the approval from the Seoul Metropolitan Council. To secure the budget of KRW 384 billion for the restoration, the municipality utilized KRW 100 billion that was initially assigned for the overall renovation of Cheonggye elevated highway. It also saved some KRW 100.4 billion by downsizing less urgent projects and introducing creative work procedures to enhance efficiency of the city administration. The rest of the budget was secured from the city's general accounting. Further, donations were made on some bridge. The project fund for Samilgyo, Mojeongyo, Gwangtonggyo and Jangtonggyo was donated, allowing the municipality to save KRW 8.2 from the budget. In total, KRW 384.4 was invested in the project. The amount was merely about 1% of the total budget of the Seoul municipality, which was not burdensome at all. Compared to other waterway restoration projects in Korea and abroad, the Cheonggyecheon restoration project was highly economical.

Results and impacts
  • Improvement of environment:

Creation of wind corridor, reduction of heat island effect, better air quality, and restoration of natural environment Physical change and reduced traffic volume in the Cheonggyecheon area reportedly reduced the concentration of fine dust (PM-10), NO2, volatile organic compound (VOC) and other air pollutant in a significant level, shorty after the restoration. The heat island effect in the downtown also declined. The temperature of the Cheonggyecheon area before the restoration was 2.2℃ higher than the average of Seoul, but it declined to 1.3℃ after the restoration, dropping by 8 to 18%. The temperature of green point within the stream was 0.9℃ lower than neighboring area, As air-blocking elevated highway disappeared, wind corridor was established and the creation of stream affected neighboring environment. Ecosystem was also restored as wildlife fish species, birds, insects and plants increased.

  • Flood control

Cheonggyecheon is the lowest-lying area in the old downtown with an extensive basin to collect rainwater and gently sloped banks, which make it a highly flooding-prone stream. Overflow occurred for two consecutive years before the restoration began, causing damage in the downtown area. Given that local torrential rainfall is frequent in Seoul, discharge area of the restored stream was designed on the basis of 200-year recurrence interval. While the estimation at 200-year recurrence interval had revealed that most of the low-lying area around Cheonggyecheon had been subject to inundation before the restoration, there was no report of flooding due to lack of discharge area after the restoration, which means that the vicinity was made free from flooding damage.

  • Increased public space, pedestrian-friendly environment, more floating population and tourists

The floating population in the Cheonggyecheon area of weekdays and weekend recorded a significant increase. The increase was larger in weekdays than in weekends, meaning that citizens visit the stream often in their daily lives. In the 2013 survey, 89% of respondents were on the fence or satisfied with the walking trail along the stream. They were particularly satisfied with the uniqueness of the place itself. However, they showed lower level of satisfaction in accessibility, because the access from the ground level to the stream was limited due to the stream's narrow width. From the perspective of citizens, the biggest contribution of the restoration was the creation of a place to relax. In the 2013 survey, 59.6% of respondents indicated so. Cheonggyecheon also became a venue for diverse cultural events: 259 events were hosted in 2005-07, firmly positioning the stream as a place for culture and recreation.

  • Changes in citizens' consciousness

One of the big achievement of the Cheonggyecheon restoration was the citizens' awareness on the value of natural environment. Even before the restoration project, people already had interests in natural environment and aspiration for a better Cheonggyecheon. After witnessing the restored stream and its environment, people's recognition on the value further increased. According to a survey on citizens' willingness to pay for a natural stream before and after the restoration project, the annual economic value of a natural stream appreciated by the citizens jumped from KRW 20,226 to 37,724 per household. The survey confirmed that the citizens of Seoul placed a higher value on the natural environment after experiencing the restored Cheonggyecheon.

Barriers and challenges

Technical Challenge

  • Short construction period, limited budget, and waste recycling

As announced in 2001, Cheonggyecheon was planned to be demolished and renovated in three years from 2002, during which inconvenience of neighboring merchants was inevitable. Since the main complaint of neighboring merchants was to minimize construction period, it became a priority to complete the work as soon as possible. In order to shorten the construction period and accommodate a diversity of creative ideas from the private sector, the contract for the project was processed in the "fast-track design-build" system. Among the companies participated in the bidding process, based on the basic design guidelines developed by the city government of Seoul, contractors were selected. Since three different entities designed each zone separately, the city government intervened to ensure consistency and solve the problems such as concept differences or errors in sewage pipeline's connectivity between each zone. The construction started in July 2003, and major structures were demolished by October. During demolition, the detailed design for construction works in the stream was developed simultaneously, and the construction was completed in the early 2005. After a series of test-run during the rainy season, the project was completed by September 2005, taking 27 months in total. 96% of waste generated during the construction was recycled.

Lessons learned and transferability
  • Creative envisioning

"Envisioning" is the most important keyword in the restoration of Cheonggyecheon. Eliminating 18 busiest lanes at the heart of Seoul was certainly something beyond imagination, given that cars were continually increasing and traffic jams were intensifying. Many people concerned the traffic chaos and strongly opposed the plan. However, the elimination of roads and the creation of a waterfront made the downtown more environmentally pleasant and vibrant. The quality of lives of the people improved, and their awareness on public space also changed. Contrary to the prediction of many experts, the transportation system moved quickly to public transit-oriented, which improved the downtown traffic condition.

  • Leadership

Leadership is crucial in such a ground-breaking transition. A leader should be able to present a clear vision, run the organization and its human resources in an efficient way, resolve the internal skepticism and external conflicts, and communicate and persuade people. Such a leadership actually facilitated the renewal of urban space. In particular, the role of a leader was crucial in leading the organization of public officials effectively, preventing potential cacophonies through constant discussions, altering the organization to focus on the work at the site to ensure efficiency, and persuading different stakeholders to build the consensus.

  • Appropriate implementation system and efficient project management

At the initial stage of the project, the citizens' committee composed of the general public and experts contributed a lot to setting the project's direction by gathering different opinions and building consensus. The restoration could not be achieved with partial approaches. Coordination between different sectors of work―water, road, sewerage, civil engineering, gardening, architecture, urban planning, economics, social affairs and welfare―was crucial to move forward. It was thus appropriate that the municipality appointed a vice-mayor level official to take a responsibility for organizing and coordinating the project effectively. Also, the weekly meeting held at 8am every Saturday played a key role in speedy decision-making and resolution of conflicts between different city departments. As a result, the project could be successfully completed within the target deadline, without exceeding the budget by a large margin.

  • Public-Private partnership, and the triangular implementation system

It is also noteworthy that a close public-private partnership contributed to the downtown transformation. To this end, the triangular implementation system consisting of the administrative agency to implement the project, a research body to provide expertise and a citizens' committee to gather citizens' opinions worked effectively. Such a practice paved the way for the emergence of collaborative planning in the urban planning of Seoul.

  • Pros and cons of politicalization

Politicalization of the Cheonggyecheon restoration was a double-edged sword. While the political momentum certainly drove the restoration project more powerfully, the project became a subject of political controversy, rather than a factor of urban revitalization. It also became a matter of political strife in the mayoral election every four years. Despite the necessity of long-term management, the public sector could not fully ensure the consistency in managing the Cheonggyecheon restoration and urban revitalization efforts. It is unfortunate that the task of urban revitalization exclusively fell to private sector, due to the absence of public intervention.


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