Where's the Best Place to Walk in the Heat? Complete Shade Analysis of Gangnam's 3 Districts

On a Summer Day, Where Will You Walk?

On a summer day with a heat wave warning in effect, which district would be coolest to walk in: Gangnam-gu, Seocho-gu, or Songpa-gu?

"Obviously the place with the most street trees!"

Is that really true? The data tells a slightly different story.

According to a 2022 study by the Seoul Institute, street tree shade can lower the temperature of surrounding objects by 15.4 degrees.

Reversed Rankings, Surprising Results

Street Tree Count Rankings

1st Gangnam-gu: 12,803 trees
2nd Songpa-gu: 12,717 trees  
3rd Seocho-gu: 11,786 trees

The number of analyzed street trees in all three districts is similar. The difference between Gangnam-gu with the most trees and Seocho-gu with the least is only about 1,000 trees.

Shade Coverage Rankings

1st Seocho-gu: 87.3%
2nd Songpa-gu: 85.1%
3rd Gangnam-gu: 80.3%

But when we look at shade coverage, the rankings flip.

Seocho-gu has the fewest street trees but provides the most shade, while Gangnam-gu has the most trees but provides the least shade. How did this happen?

The Secret Was in the Size of Street Trees

The answer lies in the size of the street trees.

Crown width refers to the spread of a tree's branches and leaves. It's a crucial value that determines the size of shade a street tree creates.

The average crown width of Seocho-gu's street trees is 5.6m. Songpa-gu's is 4.3m. It's only a 1.3m difference, but this creates a significant impact.

How do we calculate shade area?

We assume the shade created by one street tree is circular. We calculate the area of a circle with the crown width as the radius. (In technical terms, this is called Crown Projection Area, or CPA for short)

One tree with 5.6m crown width = about 24.6㎡ (7.5 pyeong) of shade
One tree with 4.3m crown width = about 14.5㎡ (4.4 pyeong) of shade

The shade difference per tree is about 10㎡ (3 pyeong).

Why is this important? According to a Nature (2014) study, one large tree absorbs as much carbon per year as several medium-sized trees. A Frontiers in Forests (2020) study also revealed that large trees make up only 3% of the total but store 42% of the carbon.

Large street trees are superior not only for shade but also for environmental benefits.

Seocho-gu: The Power of Large Street Trees

Seocho-gu demonstrates a "growing over planting" strategy.

Top 5 Roads with Excellent Shade in Seocho-gu

Let's look at Jamwon-ro. It has only 195 trees but achieves 103.3% shade coverage. How can it exceed 100%?

It's because the trees are so large that their shade overlaps. The average crown width per tree is 10.0m. Each tree creates 78㎡ (24 pyeong) of shade.

Seocho-gu's Success Story: Yangjae Stream Metasequoia Street

There's a prime example showing how successful Seocho-gu's "growing" strategy has been: Yangjae Stream Metasequoia Street.

• Length: About 3.5km
• Street trees: About 830 trees
• Achievement: Selected as one of 'Korea's 100 Most Beautiful Roads'

Street trees carefully nurtured over time have now become a Seoul landmark. This is a great example of successful "growing over planting."

Characteristics of Seocho-gu

• Average crown width of 5.6m, ranking 1st among Gangnam's 3 districts
• Plants fewer trees but grows them larger
• Success story of "growing over planting" strategy
• Superior and stable shade quality (lowest Very Poor section rate at 4.8%)
• According to Kyunghyang Shinmun (2021), London plane tree streets are well-established, "providing good noise reduction effects and creating large shade in the city"

Seocho-gu Shade Map

Interactive map visualizing shade connectivity of Seoul's street trees. Roads are color-coded from green (excellent) to red (poor) based on shade coverage ratio, and line thickness represents street tree density. Click on the map to view detailed information including number of trees, average crown width, and shade distance for each section.

Important Notes for Interpretation:

• Shade ranges are estimated values based on street tree crown width data; actual shade may vary depending on season, time of day, and solar elevation.
• This visualization analyzes only street tree shade and does not reflect shade from buildings or structures.
• Analysis was conducted separately for both sides of roads (Side A/Side B), so shade conditions may differ by direction even on roads with the same name.

Songpa-gu: The Power of Dense Planting

Songpa-gu demonstrates a "small but many" strategy.

Songpa-gu Characteristics:
- Number of trees: 12,717 trees (2nd place)
- Average crown width: 4.3m (3rd place, smallest)
- Shade coverage: 85.1% (2nd place)

How could it maintain 2nd place in shade coverage with the smallest average crown width?

Roads with Excellent Shade in Songpa-gu

The secret is dense planting intervals. Songpa-gu's average street tree spacing is 6.73m, about 1m narrower than Gangnam-gu's (7.65m). Despite smaller crown widths (4.3m), they secured shade continuity by planting trees at close intervals without gaps.

Characteristics of Songpa-gu

• Overcame crown width limitations by planting small trees at regular intervals
• Highest Excellent grade (95%+ shade coverage) ratio at 70.3% among the 3 districts!
• Provides stable shade in many sections

Songpa-gu Shade Map

Interactive map visualizing shade connectivity of Seoul's street trees. Roads are color-coded from green (excellent) to red (poor) based on shade coverage ratio, and line thickness represents street tree density. Click on the map to view detailed information including number of trees, average crown width, and shade distance for each section.

Important Notes for Interpretation:

• Shade ranges are estimated values based on street tree crown width data; actual shade may vary depending on season, time of day, and solar elevation.
• This visualization analyzes only street tree shade and does not reflect shade from buildings or structures.
• Analysis was conducted separately for both sides of roads (Side A/Side B), so shade conditions may differ by direction even on roads with the same name.

Gangnam-gu: Most Street Trees, Diverse Planting History

Gangnam-gu has the most street trees but the lowest shade quality.

History of Gangnam-gu Street Trees

Gangnam-gu has had systematic street tree planting since the Gangnam development period of the 1970s. When rapid urban development made the environment barren, the government led efforts to plant mainly London plane trees along major roads.

In the mid-1980s, Sinsa-dong residents voluntarily planted 147 ginkgo trees, creating what is now 'Sinsa-dong Tree-lined Street.' This resident-led street tree initiative remains a representative landmark of Gangnam-gu to this day.

Gangnam-gu's Paradox

There's an interesting fact. According to Newsis reports, Gangnam-gu has 23,729 street trees, the most among Seoul's 25 districts. This is much more than the 12,803 trees included in our analysis.

Despite having the most street trees, it has the lowest shade coverage. The wide average spacing of 7.65m appears to be the main cause.

Gangnam-gu by the Numbers

Gangnam-gu's average street tree spacing is 7.65m, about 1m wider than Seocho-gu and Songpa-gu (6.73m). Wide spacing makes it easy for shade connections to break.

Analysis of Roads with Poor Shade in Gangnam-gu

Rodeo-gil is a commercial hub densely packed with dining, fashion, and shopping facilities. The closely arranged buildings create a structure where space for planting street trees is inherently limited.

Gangnam-gu Shade Map

Interactive map visualizing shade connectivity of Seoul's street trees. Roads are color-coded from green (excellent) to red (poor) based on shade coverage ratio, and line thickness represents street tree density. Click on the map to view detailed information including number of trees, average crown width, and shade distance for each section.

Important Notes for Interpretation:

• Shade ranges are estimated values based on street tree crown width data; actual shade may vary depending on season, time of day, and solar elevation.
• This visualization analyzes only street tree shade and does not reflect shade from buildings or structures.
• Analysis was conducted separately for both sides of roads (Side A/Side B), so shade conditions may differ by direction even on roads with the same name.

How Good is the Shade Quality?

We graded each district's roads based on shade quality.

Songpa-gu: Highest Excellent grade ratio at 70.3%. 7 out of 10 roads have excellent shade!

Seocho-gu: Lowest Very Poor grade ratio at 4.8%. Most stable shade quality.

Gangnam-gu: Highest Very Poor grade ratio at 10.3%. Many roads urgently need improvement.

Key Summary

What This Analysis Reveals

1. Size Matters More Than Quantity

Even with similar numbers of street trees, shade quality can differ. What matters is the size (crown width) and arrangement of street trees.

Seocho-gu has about 1,000 fewer trees (11,786 vs 12,803), but the average crown width is 0.4m larger (5.6m vs 5.2m). This small difference created a 7%p difference in shade coverage.

This isn't just our opinion. A University of Melbourne study (2024) that ran 30-year simulations found that a strategy maximizing the number of trees achieved 11-15% canopy cover, while a strategy prioritizing large-canopy species achieved 16-22%. This is scientific evidence that planting large trees is more effective.

2. Two Successful Strategies

• Seocho-gu: Growing large street trees (average crown width 5.6m)
• Songpa-gu: Densely planting small street trees (12,717 trees)

Both strategies have their advantages. What matters isn't "planting many" but "how to plant and how to grow them".

3. "Growing Over Planting" is Seoul City's Policy Direction

The core of the 2040 Seoul City Park and Green Space Master Plan (conditionally approved February 2025) is "not quantitative expansion of park area but qualitative improvement of green spaces". Seoul Environmental Movement Union (2025) also proposed "shifting management methods from expert-led creation and pruning to resident-participatory care-focused approaches".

Our analysis's "growing over planting" proposal aligns exactly with this policy direction.

Interesting Facts

Shade coverage can exceed 100%

When street tree shade overlaps, it can exceed 100%. Seocho-gu's Heonneung-ro has 112.3%, meaning the shade overlaps by 12.3%. This creates deeper, cooler shade.

This might seem strange, but it's an academically recognized concept. According to the RISC (Range Inventory Standardization Committee) official definition, "Canopy cover can exceed 100%".

The Magic of Tree Size

One tree with 5.6m crown width = about 24.6㎡ (7.5 pyeong) of shade

One tree with 4.3m crown width = about 14.5㎡ (4.4 pyeong) of shade

It's only a 1.3m difference, but the shade area differs by 10㎡ (3 pyeong).

Amazing Abilities of Large Trees

According to a Nature (2014) study, the larger a tree gets, the more carbon it continues to absorb annually (confirmed in 97% of species). A Frontiers in Forests (2020) study revealed something even more remarkable:

• Large trees (diameter 53cm or more) make up only 3% of the total
• But they store 42% of the carbon

This is scientific evidence that one large tree is better for