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Flatten SF is a browser-based tool for comparing walking and biking routes between San Francisco locations by distance and cumulative elevation gain. Its creator says it uses USGS one-meter lidar elevation data and an Overture/OpenStreetMap street graph; the site does not provide evidence about route accuracy or user adoption.
Users enter a starting point and destination, then move a slider across the trade-off between shorter travel and less climbing. Flatten SF says it displays routes that are not beaten by another option on both measures, from the shortest path to a flatter route the tool considers worth walking. Moving the slider to the right does not shorten the route or add climbing, according to the site.
The route calculations use USGS one-meter lidar elevation data and a street graph from Overture and OpenStreetMap, the site says. Place search works offline because San Francisco streets, intersections, places and addresses are built into the page. The site also distinguishes travel modes: it allows stairways for walking and excludes them for biking.
Flatten SF measures climbing as cumulative elevation gain, rather than the net elevation difference between a route’s endpoints. Its slider uses a stated trade-off in which a foot of climb costs 200 feet of walking; the site says routes beyond that point stop being routes. Faint lines on the map show other options along the distance-and-climbing trade-off.
Choosing Between Hills and Distance
San Francisco’s hills can make two routes of similar length feel different to walk or ride. By showing distance alongside cumulative climbing, Flatten SF makes that trade-off visible before a trip, which may help users choose a route that better fits their preferences or physical needs.
The tool’s value depends on how accurately its elevation data and street graph represent real conditions. Its route display offers a comparison, but the source material does not establish that the suggested paths are accessible, comfortable, open, or suitable for every traveler. Users still need to judge whether a particular route works for them.
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How Flatten SF Builds Routes
Flatten SF describes itself as a tool for finding flatter routes across San Francisco. Its calculations run in the user’s browser, drawing on USGS one-meter lidar for elevation and an Overture/OpenStreetMap street graph for route connections. The page credits Drew Edwards and links to source data and a fuller analysis.
The slider is designed to show a range of options rather than a single shortest path. Routes on the displayed trade-off cannot be improved on both distance and climbing at once, according to the site’s explanation. The source material does not give a publication date, explain how often the underlying data is updated, or report independent testing.
“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 website
Accuracy and Coverage Questions
The source material does not state when the tool launched, how frequently its street and elevation data are refreshed, or whether its routes have been independently checked against on-the-ground conditions. It also does not provide user numbers, performance measurements, or evidence that every address and path is represented.
The meaning of the site’s 200-foot walking trade-off is a design choice; the available material does not say how it was selected or whether users can change it. It is also unclear how the tool handles temporary closures, construction, private access, or other conditions that could affect a route. The site explains that stairs are included for walking and excluded for biking, but gives no further detail about accessibility information.
Using the Route Comparison Tool
People can try the planner on the Flatten SF website by selecting two San Francisco locations and moving the slider to compare distance and climbing. The site also links to its source data and full analysis, which offer a route to inspect how the tool was built.
No future release, data update, or independent review is identified in the supplied material. Users considering a route can compare the options in the planner and check current street conditions and access before setting out.
Key Questions
What does Flatten SF do?
Flatten SF compares routes between San Francisco locations by distance and cumulative climbing, allowing users to explore options between the shortest route and flatter alternatives.
What data does the tool use?
The site says it uses USGS one-meter lidar elevation data and an Overture/OpenStreetMap street graph. It says route calculations run in the browser.
Does the tool include stairs?
According to the site, stairways are allowed for walking and excluded when calculating bike routes.
How does Flatten SF measure climbing?
It uses cumulative elevation gain along the route, not the difference between the starting and ending elevations.
Does the source confirm that every route is accessible or current?
No. The supplied description does not report independent route checks, data update frequency, or accessibility coverage. The site explains its data sources and routing rules, but those details alone do not confirm current conditions on each street.
Source: hn
