Catchment Area

What It Does

The Catchment Area model defines the population reachable from the site within 5, 10, and 15-minute travel bands. It gives a ground-truth picture of how many people can realistically reach you without effort — and how many restaurants they’re also choosing from.

Current Implementation

Zone Definitions

Zone	Distance	Source
5-min walk	400 m radius	STPU census ring (maxM=400)
10-min walk	800 m radius	STPU census ring (maxM=800)
15-min transit	2000 m MTR filter	Nearest MTR stations within 2 km

When STPU data is unavailable, population falls back to:

pop5  = density × π × 0.4² × 0.85
pop10 = density × π × 0.8² × 0.85

Competitor Distribution Estimate

Competitors are not geo-coded by ring — the total FEHD count is redistributed:

comp5  = round(total × 0.5)   ← roughly half within 400 m
comp10 = total                  ← all within 800 m

This is an estimate. The actual spatial distribution of FEHD licences is not ring-bucketed in the current API.

Transit Catchment (15-min Zone)

transitPop = Σ ridership × 0.05  for all MTR stations within 2 km

5% of daily station ridership is assumed to reach the restaurant (very conservative — accounts for multi-exit catchment, destination variety, etc.).

Data Sources

• Population: Census 2021 STPU (211 zones), cumulative ring aggregation
• Competitors: FEHD licence data, 800 m radius query
• Transit ridership: MTR Annual ridership per station (static dataset)

Note

The 5-min walk population (400 m) is the single most important input for budget and takeaway concepts. For destination dining, the transit catchment matters more than the walk-in zone.

Interpretation

5-min pop	Context
50,000+	Extremely dense urban core (Mong Kok, Central)
20,000–50,000	Dense residential or mixed-use area
5,000–20,000	Typical suburban town centre
< 5,000	Low-density or waterfront/park-adjacent site

Known Limitations

• Competitor distribution (50/100% split) is an estimate — no ring-level breakdown available from FEHD query
• Transit catchment assumes 5% capture of all station ridership, regardless of station type or line
• No adjustment for actual street network (Euclidean distance, not walk-time distance)
• MTR ridership data is annual average — peak/off-peak variation not modelled

Changelog

Date	Change
2026-03-25	Population now uses STPU census zones (cumulative rings) instead of density×area estimation; competitor distribution estimate (50% at 400 m, 100% at 800 m) documented
2026-02-10	Initial implementation with density-based fallback