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Flatten SF is an interactive tool by Drew Edwards for comparing routes between San Francisco locations by both distance and cumulative climbing. Its site says routes are computed in the user’s browser using USGS one-meter lidar elevation data and an Overture/OpenStreetMap street graph.
Flatten SF, an online route-planning tool by Drew Edwards, lets users compare routes between San Francisco locations based on both distance and climbing. The site says calculations run in the browser across more than 160,000 street segments, using USGS one-meter lidar elevation data and a street network drawn from Overture and OpenStreetMap.
Users enter a starting point and destination, then use a slider to move across routes that balance shorter distance against less cumulative elevation gain. According to the site, the options span from the shortest path to a flatter route that is still considered worth walking. Moving the slider to favor less climbing does not produce a shorter route or add climbing; it moves along the set of routes that are not beaten on both measures by another option.
The tool defines climbing as cumulative gain along the route, rather than simply subtracting the starting elevation from the destination elevation. This distinction matters on San Francisco’s rolling streets: a route can finish near its starting elevation but still include repeated uphill sections. Faint lines on the map show other routes in the distance-versus-climbing trade-off.
Flatten SF says its place search works offline, with San Francisco intersections, places and addresses included in the page. The site allows stairways when calculating routes on foot and excludes them for bike routes. Its description does not provide a public launch date or independent performance testing.
Choosing Between Distance and Climbing
San Francisco’s steep streets can make the shortest route a poor fit for someone trying to limit uphill effort. By showing distance and cumulative climbing together, Flatten SF gives pedestrians and cyclists a way to see the trade-off before choosing a route, rather than treating the shortest path as the only option.
The approach may be useful for people walking with mobility limitations, carrying loads, or planning a ride, though the source material does not describe accessibility testing or claim that every route is suitable for every user. The map’s route options make the trade-off visible; users still need to judge factors such as street conditions, stairs and their own needs.
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How Flatten SF Builds Routes
The site says route calculations use USGS one-meter lidar elevation data and a street graph combining Overture and OpenStreetMap. It reports processing more than 160,000 street segments in the browser. Place lookup is also described as offline because San Francisco locations are built into the page.
Flatten SF frames route selection as a trade-off rather than a single best path. Its stated walking setting treats a foot of climbing as equivalent to 200 feet of walking when deciding how far to favor reduced elevation gain. The site says that beyond this point, routes stop being routes; it does not supply further detail in the provided material about how that threshold is applied across different users or modes.
“Routes are computed in your browser over 160,000 street segments.”
— Flatten SF website
Limits of the Route Information
The source material does not state when Flatten SF launched, how often its elevation and street data are updated, or whether route results have been independently validated against on-the-ground conditions. It also does not specify how the tool handles temporary closures, construction, private access, surface quality or other hazards.
The site describes the data sources and routing rules, but does not provide comparative accuracy results or user testing in the supplied report. Its walking trade-off is a stated tool setting, not evidence that a particular route will feel manageable for every person. Users should check route conditions and accessibility details before setting out.
Checking a Route Before Setting Out
Users can enter two San Francisco locations on the Flatten SF page and move the slider to compare routes with different distance and climbing profiles. The source material does not announce a planned update, added feature or next release. The site points readers to its source data and full analysis for further information.
Because the tool’s map data may not capture current street conditions, people planning a trip should independently verify access, closures and stairway details, particularly if those factors affect whether a route is usable.
Key Questions
What does Flatten SF do?
It compares routes between San Francisco locations by distance and cumulative elevation gain, allowing users to choose a balance between the two.
What data does the tool use?
Flatten SF says it uses USGS one-meter lidar elevation data and an Overture/OpenStreetMap street graph covering more than 160,000 street segments.
Does the tool count stairways?
According to the site, stairways are included for walking routes and excluded for bike routes.
What does cumulative climbing mean?
It is the total elevation gained along the route, rather than the difference between the elevations at the start and finish. A route that ends at a similar elevation can still include substantial uphill sections.
Is Flatten SF’s route data verified as current?
The provided source does not say how often the street and elevation data are updated or whether routes are independently checked. Users should verify current closures, access and conditions before travelling.
Source: hn
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