Into the 1970s, South Korea achieved dramatic economic growth. With it, the automobile industry also grew. One of the most important transportation policies of the time was to facilitate traffic flow, and overpasses were built in support of this policy. These structures were built mostly in the old downtown area because, at the time, traffic flowed into the city center, within the boundaries of the four old city gates. The urban expressways (e.g., Gangbyeon Riverside Expressway, Olympic Expressway, Oegwak Outer Beltway, Naebu Inner Beltway) did not exist, and all arterial roads headed toward the city center. In the 1970s and 1980s, most overpasses were built in the old town center in Gangbuk where traffic bottlenecks occurred. Eighty-six overpasses were built in Seoul during this time of constant construction.
Three to four decades later, in the 2000s, overpasses began to lose their originally intended function due to more balanced urban development as well as changes in road networks and the overall traffic system. As highly functional roads such as urban expressways were built one after another, traffic dispersed and urban concentration also eased. More than anything, the old town within the four old city gates declined and the new Gangnam areas prospered. This shift in urban concentration and “relocation” of the bottlenecks from old to new areas brought the excessive investment on overpasses to light. For instance, Ahyeon Overpass was empty except during commuting hours and its numerous sharp bends resulted in speed-related accidents. Overpasses such as this, where users were hit with a “congestion charge” to discourage them from bringing their cars into the city center, were no longer the symbol of smooth flowing traffic. The transportation policy paradigm was also changing, and more emphasis was placed on pedestrians and public transit than on vehicles.
Residents argued that overpasses blighted the cityscape, caused regional isolation, and undermined regional development. Accordingly, the argument for removing overpasses became more and more logical, which the City of Seoul began to review.  Subsequently, the city decided to remove some of them, starting with the Cheonggye Overpass connecting east and west in 2003. The removal of this first overpass resulted in a better cityscape and traffic congestion was not as severe as had been expected. Since then, the city decided to consider removal of other old, ugly overpasses that undermined the cityscape.
 

<Figure 1> Removal of Cheonggye Overpass: Before & After


Source: Internal data, Seoul Metropolitan Government
 

Another reason for this was that overpasses interfered with another program in Seoul – introduction of the center bus lane system. To install center bus lanes, a minimum of 2 additional lanes were necessary; most overpasses began at the center of roads that were 4 lanes (both ways) or narrower. Center bus lanes could not be built on roads over which overpasses occupied. On the stretch of roads where overpasses begin, congestion is frequent as cars and buses change lanes to get on their desired path. The local environment was also an element. Most areas with overpasses saw their commercial districts fade away due to the support columns, some areas even becoming slums. Many of these supports have been removed for a myriad of other reasons (deterioration, disruption of traffic flow, interference with subway construction, blighting the cityscape, etc.). More will follow suit.


 

Studies by experts show that there were approximately 40 deteriorating overpasses of 30 years of age or older, and that were not as functional as they were intended to be. Although removal of the overpasses would potentially nearly double the traffic volume, this would be compensated by better public transit service, leaving the road’s capacity for cars unchanged. In 2002, Seoul started with Tteokjeon Overpass in Jeonnong-dong and phased out overpasses that were not safe or lacked economic or environmental value, seeking to change public awareness of the changing city, improve the cityscape and urban environment, revitalize affected regions and their commerce, and enhance traffic flow and safety.

Removal Process

 
First, the City of Seoul identifies problems with traffic control and management that may arise from removal and comes up with solutions. Items to be reviewed are then determined (location and function of the intersection, traffic flow, maintenance costs, suitability with plans for surroundings, etc.) and evaluated to consider feasibility and priorities.

<Figure 2> The Removal Process


 

Examples of Removal & Consequent Measures

Removals in 2010 & 2011

Major Preventive Measures

Improved Traffic Flow

 
On many occasions, overpass removal improved traffic flow in the vicinity. Analysis of morning traffic flow before and after removal of Wonnam, Miah, and Hyehwa Overpasses shows that average speed increased in these areas except for the Hongje Overpass area. There was a tendency for a reduction in travel speed on roads immediately after the removal, but speed returned to normal levels or increased within a year or two. This improvement was due not only to overpass removal, but also i) physical changes (e.g., increased capacity of intersections due to expanded access; geometric improvement of intersections previously limited by overpass support columns; channelization of turn lanes); and ii) systemic changes (e.g., improvement of signal operations and route management; control of turns at intersections).
 

<Figure 3> Changes in Average Travel Speed after Overpass Removal



 

Financial Effect: Greater Revenues for Adjacent Businesses & Increased Housing Prices

 
In many cases, housing prices go up when an overpass is removed. The City of Seoul compared officially-assessed land prices in the vicinity of the overpasses and found that the land prices increased faster near the removed overpass than in nearby regions. Figure 4 shows the official real estate prices in adjacent areas after removing 4 overpasses in Seoul; growth rate is high immediately before and after demolition. When the Tteokjeon Overpass was removed in 2002, prices of real estate in the surrounding area rose by 18% in 2003 and 2004 whereas the average growth rate in all of Dongdaemun-gu (where the overpass had been) was only 5.09% during the same period. Prices of land near the Miah Overpass, removed in 2004, rose by 16% in 2005 and 2006 – about 10% higher than the 6% growth rate of Seongbuk-gu and Gangbuk-gu.

 
<Figure 4> Changes in Real Estate Prices in Immediate Vicinities after Overpass Removal


Note: Red circle denotes year overpass was removed.
Source: Internal data, Seoul Metropolitan Government.
 

Greater Value to the Surrounding Landscape

 
In terms of landscape, the view of the intersections is more open and sweeping after an overpass is removed, as seen in Figure 5. It is expected that people who enter the region are more satisfied with the view.
 
<Figure 5> Before and After Overpass Removal



Source: Internal data, Seoul Metropolitan Government.
 
 

Removing old overpasses that undermine the cityscape and regional development brings positive results to local residents and others passing through, but there are still experts and residents who believe that the removal is less ideal in terms of traffic flow, partly due to a lack of studies that clarify the socioeconomic effects of the removal. It is therefore necessary to continue monitoring and analyzing the effects, the results of which can be used later to set the course for future direction.

Kim Jong-hyeok, Kim Jin-tae, Kim Hong-gil, Shin Bok-min, 2013, “Analytical Study on the Removal of Overpasses in Seoul & Consequent Benefits from the Improved Cityscape”, Seoul Studies, Volume 14, Issue 4.
Kim Jong-hyeok, Kim Hong-gil, 2011, “Before & After Overpass Removal in Seoul”, Road Transport #125.Seoul Metropolitan Government, 2012, “Comprehensive Report on Detailed Design for Demolition of Seodaemun & Ahyeon Overpasses”.