Cheonggyecheon Stream Restoration — Seoul Replaces a Downtown Expressway with a 5.8 km Urban Stream

Between 2003 and 2005 the Seoul Metropolitan Government demolished an ageing elevated expressway that covered the Cheonggyecheon stream in the city centre and restored an open, pumped stream corridor of about 5.8 km, accompanied by bus-service expansion, car restrictions and higher parking fees.
Reported results (Landscape Performance Series methodology, citing Kim, Koh & Kwon 2009 and Kang & Cervero 2009): temperatures along the stream were 3.3–5.9°C cooler than on a parallel road 4–7 blocks away; small-particle air pollution fell 35% (74 to 48 µg/m³); recorded species counts rose from 62 to 308 plants, 4 to 25 fish and 6 to 36 birds between 2003 and 2008; bus ridership in Seoul rose 15.1% and subway ridership 3.3% over 2003–2008; land prices within 50 m rose 30–50%, about double the rate elsewhere in Seoul. Leaving the expressway in place would have needed about ₩100 billion of repairs, against a restoration cost roughly ₩289 billion higher.
Caveats: most figures come from the city's own management agencies; metropolitan traffic did not seize up as feared, but some parallel roads became busier; the stream depends on continuous pumping and carries a permanent operating cost; and the 30–50% land-price rise signals gentrification and displacement pressure that the sources do not evaluate. The case is best read as a well-documented but self-reported flagship, not a controlled evaluation.

Read the full analysis: https://landscapeperformance.org/sites/default/files/Cheonggycheon Methodology.pdf