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Flatten SF, a web tool by Drew Edwards, calculates routes between San Francisco locations and lets users compare distance with cumulative climbing. Its creator says the browser-based calculations use USGS one-meter lidar elevation data and an Overture/OpenStreetMap street graph; the tool also treats stairways differently for walking and biking.
Flatten SF, a web-based route planner by Drew Edwards, lets users compare paths between San Francisco locations by how far they travel and how much they climb. The tool calculates routes in the browser using elevation and street-network data, offering a way to weigh steepness against distance for trips on foot or by bike.
Edwards says the system computes routes across more than 160,000 street segments, drawing on USGS one-meter lidar elevation data and a street graph from Overture and OpenStreetMap. Users enter starting and ending locations and move a slider across routes that trade shorter travel for less climbing. Place search works offline, with San Francisco intersections, places and addresses built into the page.
The slider presents routes that are not beaten by another route on both distance and climbing. According to the site’s explanation, moving toward the flatter end of the scale does not produce a shorter route or add climbing. The calculation counts cumulative elevation gain, rather than simply comparing the elevation at the start and finish; a route can descend and climb again while still ending near its starting elevation.
Stairways are included for walking routes and excluded for biking routes, the site says. Faint lines on the map show other routes along the distance-and-climb trade-off. Edwards describes the flatter end as the point where a foot of climbing is treated as costing 200 feet of walking, beyond which the alternatives stop being routes under the tool’s model.
Choosing Between Climb and Distance
For people navigating San Francisco’s hilly street network, a route’s length alone may not reflect how demanding it feels. Comparing distance with accumulated climbing can help walkers and cyclists choose a route that better fits their plans, mobility, time or effort preferences. The tool makes that trade-off visible instead of returning only one shortest path.
The results are calculated routes, not a stated guarantee about real-world accessibility or travel conditions. The site provides a way to inspect alternatives; users still need to judge whether a route suits their needs and mode of travel.
portable bike computer with elevation tracking
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How Flatten SF Models Routes
Many route planners prioritize travel distance or estimated time. Flatten SF instead lays out a range of options between the shortest route and routes that reduce climbing, based on the street and elevation data described by Edwards. The slider’s model assigns a walking-distance cost to climbing, allowing users to explore intermediate choices rather than treating “shortest” and “flattest” as the only possibilities.
The underlying inputs include lidar measurements and street data associated with Overture and OpenStreetMap. The site’s explanation also distinguishes between modes: stairways can be part of a walking route but are left out of a bike route. Edwards links to the source, data and full analysis, though the supplied description does not give a release date or independent evaluation of route accuracy.
“Routes are computed in your browser over 160,000 street segments, using USGS 1 m lidar elevation and the Overture / OpenStreetMap street graph.”
— Flatten SF, by Drew Edwards
Limits of the Route Estimates
The available description does not specify when the tool launched, how often its street and elevation data are updated, or how its route results have been checked against conditions on the ground. It also does not say whether the map accounts for temporary closures, construction, surface quality, traffic, or individual accessibility needs. The stated 200-foot walking cost for a foot of climbing is part of the route model; the source does not establish that it reflects every user’s experience.
Review Routes Before Setting Out
Users can enter two San Francisco locations on Flatten SF and move the slider to compare the available distance-and-climb trade-offs. Edwards points readers to the site’s source, data and full analysis for further detail on the method. The source material does not identify a planned update or future milestone, so ongoing changes to the tool or its datasets are not confirmed.
Key Questions
What does Flatten SF do?
It calculates routes between San Francisco locations and lets users compare alternatives by distance and cumulative climbing.
What data does the route planner use?
According to the site, it uses USGS one-meter lidar elevation and a street graph from Overture and OpenStreetMap, covering more than 160,000 street segments.
Does it include stairs?
The site’s description says stairways are included for walking routes and excluded for bike routes.
How does the tool count climbing?
It counts cumulative elevation gain along the route, rather than just the difference between the starting and ending elevations.
Does the flattest option always mean the shortest trip?
No. Flatten SF presents routes along a trade-off between distance and climbing. Its description says moving toward flatter options does not shorten the route.
Source: hn
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