Seoul demolished a highway to revive a stream. Why?

  • Environment
  • Saturday, 11 Nov 2017

The Cheonggyecheon restoration project has benefited Seoul in various areas including tourism, environment, culture and health. Photos: Prof Dr Noh Soo-hong

Now that Kuala Lumpur is embarking on the River of Life project, it may be pertinent to look back at how Seoul had also revived its downtown area by turning a smoggy, elevated highway into a green and restful waterway.

This was one of the topics discussed at the recent Smart Cities Asia 2017 Conference and Exhibition in KL.

Tourists visiting South Korea before and after 2005 may have noticed a world of difference along the old Cheonggye highway, located in the heart of Seoul.

What was once a busy, elevated motorway that accommodated 170,000 vehicles a day was torn down and replaced with a more welcoming sight – a soothing, landscaped stream and public space.

Since the highway over it was removed, Cheonggyecheon has become a green oasis in Seoul.

Well, the stream was not airlifted into place as such. Rather, it had always been there, but was neglected and forgotten.

The Cheonggye stream, or Cheonggyecheon to the locals, is an 11km-long stream connected to the Han River that was created back in 1411 by King Taejong to cross the heart of the city back then.

Fast forward to the 20th century and “progress” meant bad news for the stream.

First, local authorities covered the upstream portion of Cheonggyecheon in 1925. By the 1940s, the stream had degraded into an open sewer and subsequently, it was paved over.

The elevated highway that used to cover Cheonggyecheon before the stream was restored.

In 1971, to accommodate increasing traffic, the Cheonggye elevated highway was built over it and by 1977, the entire stream was covered due to “development”.

The highway served as the main traffic artery in the heart of downtown Seoul for a few decades. However, its condition slowly deteriorated, and the underpass was associated with a dumping ground and unhealthy activities.

Revival and restoration

The restoration idea for Cheonggyecheon first surfaced during a casual conversation between Prof Dr Noh Soo-hong from the environmental engineering department at Yonsei University, South Korea, and his colleague in 1991.

Dr Noh Soo-hong, a professor at Yonsei University's department of environmental engineering. Photo: The Star/Norafifi Ehsan

The project eventually picked up momentum when then mayor hopeful, Lee Myung-bak, vowed to restore the stream if he got elected.

One of the reasons for the restoration was because the highway infrastructure was showing signs of trouble and needed a substantial amount of money to repair and maintain.

Lee eventually got elected in 2002 and a year later, restoration work – which involved removing some 5km of elevated highway – began and was completed in two years (Lee subsequently went on to become the president of South Korea from 2008 to 2013).

Due to insufficient rainfall, the Cheonggye stream is fed by water pumped in from the Han River. This has drawn some flak from certain parties for not being very eco-friendly.

“Along the Cheonggyecheon, there are subways and big buildings, so the water table is low. In fact, it is so low that when the rain comes, water just settles down, so that’s why we need to pump maintenance water into Cheonggyecheon,” explained Prof Noh, who was in KL recently to speak at the Smart Cities Conference organised by Knowledge Group.

He had initially proposed a more eco-friendly way of supplying water for the stream.

Currently, water from the Han river is pumped into the stream but a more eco-friendly way of supplying water is being discussed.

“In the downtown area along Cheonggye-cheon, there are two big sewer lines which flow downstream for treatment, before being discharged into the Han River.

“We are currently using 120,000 cubic metres a day as maintenance water for Cheonggyecheon, but the domestic sewer produces 400,000 cubic metres a day. My suggestion is to treat that sewer water to a quality level good enough (safe for recreational purposes) to be channelled back to Cheonggye-cheon.

“But to do that, we will need several treatment plants along the stream, which are not in place yet because the restoration work was done quickly.

“So, that is something we have to do in the future,” he said, adding that at the moment, maintaining the Cheonggyecheon requires US$2mil (RM8.5mil) annually.

Beneficial flow

The Cheonggyecheon restoration project, which stretches 5.8km in length, has brought many benefits to Seoul in terms of tourism, flood protection, cooler temperatures, plant/animal life, cultural heritage and residents’ health.

“Since it opened in 2005 until June this year, more than 233 million people have visited Cheonggyecheon. Besides being a new attraction for citizens, the project has also played key roles in the environment,” said Prof Noh.

The restored stream is now a popular public space for recreation as well as events like this lantern festival.

It also reduces the impact of floods, including huge inundations that are calculated to happen only once every 200 years.

“The temperature along the stream is lower by 10-13% compared to the streets nearby,” he added. Faster winds blowing along the stream also cool down urban heat islands (metropolitan areas that are much warmer than the rural areas surrounding it).

The ecosystem has also seen an increase in the number of plant and animal (birds, fish, insects, amphibians, aquatic invertebrate) species – from 98 species before restoration to 864 in 2010.

Haze (small-particle air pollution) also went down by some 35%.

Before the restoration, residents in the area were more than twice as likely to complain of respiratory diseases compared to those living in other parts of the city.

Detractors of the project said that removing the highway would cause traffic problems. However, policies that encouraged public transport, such as bus-only lanes and free shuttle services from subway stations, showed that traffic congestion did not worsen in the area, said Prof Noh.

The project also played a role in heritage restoration, where two historical stone bridges built in the 1400s have been preserved.

The historical Gwangdong stone bridge which has been preserved as a cultural heritage. Filepic

One of them is the Gwangdong bridge, or Gwangdonggyo, which was hidden under the former elevated highway. It can now be appreciated by the public.

Meanwhile, Supyog bridge was relocated to a park called Jangchungdan during the restoration work and is currently still there, although there are plans to move it back to Cheonggyecheon.

The storefronts along the stream have also changed, from shops selling tools and hardware (which have been relocated) to more snazzy F&B, fashion and retail outlets catering to tourists.

In future, two rivers upstream of Cheonggyecheon – Baegundong and Junghak – which have also been covered up, will be restored by 2030 under the Cheonggyecheon 2050 Master Plan.

Seoul has proven the value of rejuvenating streams and rivers in cities, and it is hoped that KL’s River of Life will be equally successful in its aspirations.

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