Motivation for regeneration. We used the Cheonggyecheon area for a sewer and for roads. But as the economy developed, Cheonggyecheon faced problems of congestion as you see in the picture. Lots of congestion followed by lots of social problems.
 
Also, the downtown area began to decay. Seoul's downtown population decreased by 52% from 620 thousand to 300 thousand. Floor area changed a little from 790 ha in 1985 to 797 ha in 1995, while Seoul's total floor area increased by 81.5% from 13,747 to 24,696 ha.
 
And also in terms of social perspective, low-income household rose to 35%, which was 2.5 times the Seoul's average. Most of the people in their 20's and 30's moved out of the downtown area. The decaying downtown area was a big problem and it was caused by the degradation of environment like pollution and congestion.
 
And also, the number of enterprises in downtown decreased by 24.1% while that of Seoul increased by 24.6%. The number of workers in downtown also decreased by 54.3%. Downtown's share of business fell from 18.9% in 1991 to 11.7% in 2000. So we can observe the decline of the downtown area which was caused by mainly the pollution and degradation.

This is the research on the cost of congestion. The blue line shows transportation speed. The average speed of travel in the downtown area went from 30 to 13, which was more than half of the speed decreasing. The gray bar shows the social cost of congestion, which reached 7 trillion Korean Won by 2007.

This was a problem that needed to be fixed and the downtown area was in need of revitalization. This is a graph showing the change of population. The blue line shows the population of Seoul, which increased. The downtown population, shown by the red line, decreased despite the increase of Seoul's total population.
 
Another direct motivation for restoration comes from the structural problem. As you can see in the picture, the elevated highway that covered Cheonggyecheon was built in the 1970's and structural problems occurred because of aging. The elevated highway could not support heavy vehicles and provided only limited transportation. Here's the summary of the motivation.
 
The first thing was the issue of safety. Structural problem faced by the highway was an issue and something needed to be done. The Seoul government issued a plan to rebuild the elevated highway. But later on the government changed its decision from rebuilding to restoration.

The second motivation was that the Seoul government wanted to create an eco-friendly and human-oriented environment with more nature. And the third motivation was culture and history. As it was the downtown area rich with cultural heritage, Seoul wanted to revive the diverse and vibrant cultural and historical assets in Cheonggyecheon.
 
And the fourth motivation is the economy. As the downtown area declined, Seoul government wanted to vitalize this area through redevelopment for the 21^st century.