Flatten SF maps the least steep walking or biking routes between any two points in San Francisco

Drew Edwards launched Flatten SF, a browser-based routing tool that finds routes across San Francisco based on trade-offs between distance and cumulative climbing. It uses USGS lidar elevation data and Overture/OpenStreetMap street graphs to compare more than 160,000 street segments, with separate handling for walking and biking.

The project shows how richer open geospatial datasets can enable highly local, specialized navigation tools beyond generic shortest-path maps. For hilly cities, elevation-aware routing can meaningfully improve accessibility, comfort, and bikeability, especially when users can tune the balance between speed and effort.