Seoul / Reshaping the Streetscape (I): why are highways removed instead of constructed?

The measures in mitigating the possible traffic congestion came in multiple folds. Besides the change in bus route system introduced in 2004, immediate measures were also applied along Cheonggyecheon to ensure the traffic could run smoothly even after the demolition of highway.

The most explicit effect brought to the road condition was the reduction in lanes for vehicles. The number of lanes between the two sides of the original Cheonggye highway reduced from twelve to six or even four in some sections after the demolition. Though the road surface for vehicles reduced drastically after the revitalization project, large scale traffic congestion did not happen due to a multitude of traffic control policies including upgrading of bus route system, increase of shifting frequency in traffic light signals, reserving lanes for bus in busy hours, etc. The Bus Rapid Transfer System with a lower cost was installed along the route of original highway to encourage public to use the public transport. Tolls and parking fee were increased, whereas tolls were reduced for those drivers who joined the voluntary weekly “No Driving Days”. (Vanderbilt, 2010) In short, the improvement in public transport network increased the citizens’ usage in public transport and hence changed their habit in driving.

Route and Number Systems
Numbering system and service area of Bus (World Health Organization, 2011)

The removal of Cheonggye Expressway was only one of the highway demolition series. Since 2002, there were 18 highways out of the 101 in the city being torn down (Dunbar, 2015). Why would these events happen despite the possible chaos in traffic? It can be explained by the Braess’ Paradox proposed by mathematician Dietrich Braess in 1968 (Mesmer, 2014). The paradox pointed out that by increasing the number of roads in a city the travelling time will only paradoxically increase. This is because every traveler tends to choose the fastest way, which is normally the highways, to increase their travelling efficiency. (Dunbar, 2015.) By removing some roads in the congesting system, it can mitigate the congestion problem by diverting road users to different paths instead of the seemingly most efficient one. Therefore, the Seoul Metropolitan government has been evaluating the highway structures and demolishing some of the most unstable ones in recent years and these moves generally receive positive reactions from the public.

CGC_before and after
The road condition before and after Cheonggyecheon Revitalization Project (Kim, 2015)

The transformation in road lanes and width also changes the street life along Cheonggyecheon. At the same of the ancient stream being restored, beautification of streets also occur simultaneously. The restored stream and surrounding redeveloped streets boosted tourism to areas along it. As the streets are widen (Vidal, 2006) and cleaned up, People can reoccupy the streets that were in the past occupied by hawkers. The reduced traffic also provides better air quality and lower temperature in the area, which provides a better strolling experience to pedestrians.

1. Dunbar, J. 2015. “Seoul says ‘adieu’ to another overpass with blowout party” on The Korea Observer. Accessed on 18 December 2015 from
2. Mesmer P. 2014. “Seoul demolishes its urban expressways as city planners opt for greener schemes” on the guardian. Accessed on 18 December 2015 from
3. Vanderbilt, T. 2010. Unbuilt Highways. Accessed on 16 December 2015 from
4. Vidal, J. 2006. “Heart and soul of the city” on the guardian. Accessed on 16 December 2015 from

Image references:
1. Kim, N-h. 2015. “The Cheonggyecheon We Know of Today” on Internet Hanyang News. Accessed on 18 December 2015 from
2. World Health Organization. 2011. Report on ESHUT – Seoul, the Republic of Korea. Accessed on 18 December 2015 from

2 Comments on “Seoul / Reshaping the Streetscape (I): why are highways removed instead of constructed?

  1. The question of the topic of this narrative is an interesting one, “Why highways are removed instead constructed”. Opposite to the role of a highway, which is usually perceived as a solution for fast and convenience traffic flow, in Seoul, it actually burdens the traffic. It would be great to include figures or public reviews to compare the effects before and after the demolition of the highways.

    • According to the data from Seoul Metropolitan Government in 2006, the average speed of traffic in the Central Business District has recorded a slight decrease of 1.9km/hr after the project was completed. Yet the in/out flow of cars has also decreased from 1.56 million to 1.27 million. This shows that though the traffic is a bit slower in the CBD area, the number of vehicles also reduce. More people are encouraged to take public transport, with 6-9% increase in both bus and subway usage. There was in general no serious traffic congestion reported after the project.

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