WEP 5 Hut Access Isochrones

Spatial computation and storage of accessibility isochrones in PostGIS.

Computation Workflow

1. Batch Processing: Generate isochrones for all huts
2. Profile Combinations: foot, bike, ski, car
3. Time Intervals: 30min, 1h, 2h, 4h, ...
4. Seasonal Updates: Winter (ski) vs Summer (hiking/bike)
5. PostGIS Storage: Polygons with spatial indexing

Use Cases

• Hut Search: Find huts within X minutes of user location
• Accessibility Analysis: Visualize reachable areas from each hut
• Route Planning: Multi-modal journey planning
• Statistics: Hut network coverage and accessibility metrics

Performance Considerations

• Spatial Indexing: Use GIST indexes for fast polygon queries
• Precomputation: Batch updates during off-peak hours
• Caching: Cache frequent queries (popular huts, time ranges)

Data Model

PostGIS Storage

CREATE TABLE hut_isochrones (
    id UUID PRIMARY KEY,
    hut_id UUID REFERENCES huts(id),
    profile VARCHAR(20), -- foot, bike, car, ski
    max_time INTEGER, -- minutes (30, 60, 120, 240)
    geometry GEOMETRY(POLYGON, 4326),
    created_at TIMESTAMP,
    season VARCHAR(10) -- summer, winter, all
);

CREATE INDEX idx_hut_isochrones_hut_profile ON hut_isochrones(hut_id, profile, max_time);
CREATE INDEX idx_hut_isochrones_geom ON hut_isochrones USING GIST(geometry);