Footnote: The walk that works for you.

Inspiration

Most navigation apps optimize for one thing: getting from A to B as quickly as possible. But when you're walking through a city, the fastest route isn't always the route that works best for you.

A few extra minutes might be totally worth it for more shade on a hot day, better rain cover, fewer steps, a place to rest, access to a restroom, or simply a more enjoyable walk.

New York City publishes an incredible amount of data about its streets and public spaces, but that information is scattered across datasets and rarely available when someone is actually deciding how to get somewhere.

We built Footnote around a different question: what if walking directions were shaped around what actually matters to you?

City data only tells part of the story. People who walk these streets know things a dataset may not, like when a curb ramp is blocked, a bench is missing, or a sidewalk regularly floods. Those observations can become footnotes for the people who walk those streets next.

What it does

Footnote finds walking routes shaped around what matters to you, including shade, accessibility, rain cover, places to rest, restrooms, greenery, and more.

Rather than returning a single line on a map, Footnote shows what a different route actually buys you. A few extra minutes might significantly reduce direct-sun exposure, take you past places to sit, or avoid mapped steps.

For shade-aware routing, Footnote uses building footprints and heights together with the position of the sun to estimate shade along pedestrian routes. That means the best route can change throughout the day and even depend on which side of the street you walk on.

Walkers can also see footnotes left by people who came before them and contribute observations of their own, making the next person's walk more informed.

How we built it

Footnote combines public city data into a pedestrian model of New York.

We use data about buildings, streets and sidewalks, trees, parks, sidewalk sheds, amenities, and other parts of the public realm. For shade, we combine building geometry with solar position to project approximate shadows and estimate direct-sun exposure along each route.

The routing engine can then optimize for more than distance:

fastest route → reasonable alternatives → personalized scoring → the walk that works for you

An important principle is that Footnote only claims what its data can support. A sidewalk-shed permit can suggest potential rain cover, for example, but it doesn't guarantee that a sidewalk is currently covered or passable.

Challenges we ran into

One of the biggest challenges was turning the abundance of NYC OpenData into something useful for an individual person. Different datasets have different formats, update schedules, levels of precision, and limitations.

We also didn't want to build Google Maps with a shade toggle. The more interesting problem was figuring out how to use all of this information to represent the experience of walking through a city, which is different for every person.

That also meant confronting uncertainty. A mapped restroom may not be open; a tree location doesn't tell us its exact canopy. Avoiding mapped steps doesn't guarantee that an entire route is accessible, especially. We had to think carefully about the difference between what the data suggests and what it can actually prove.

What we learned

The biggest thing we learned is that there isn't one universally "best" walking route.

Some people might prefer a greener street. For others, needing fewer steps or regular places to rest may determine whether a journey works at all. A useful walking product should support both without making assumptions about the person.

We also learned that open data becomes much more valuable when it helps someone make a concrete decision. A map containing thousands of trees, benches, buildings, and permits can be overwhelming. On the other hand, saying “four extra minutes meaningfully reduces your estimated sun exposure” makes that same information useful.

Shade was what we started with, but it's only one example of a broader idea: that navigation can optimize for the experience of a journey, not just its duration.

What's next for Footnote

We want Footnote to become a richer map of the pedestrian experience.

For walkers, that means adding better accessibility information, places to sit and rest, restrooms and water, improved rain-cover data, greenery, sidewalk conditions, and true side-of-street navigation.

We also want to develop community footnotes. Walkers could leave timely observations about blocked curb ramps, missing benches, flooding, construction, or other conditions that aren't captured well by official data.

The other side of Footnote is for city planners and community organizations. Individual footnotes can be useful to the next person walking down a street, but patterns across many walks can reveal something larger. Where are people consistently encountering accessibility barriers? Where are there long stretches without places to sit? Which routes become difficult in extreme heat or rain? Where are people repeatedly taking longer routes because the pedestrian infrastructure isn't meeting their needs?

We want to build tools that turn those patterns into constructive planning insights. Planners could explore gaps in pedestrian infrastructure, understand which issues affect the most journeys, and evaluate where improvements such as seating, shade, curb ramps, restrooms, or safer crossings could have the greatest impact.

The goal is a feedback loop between the people who walk the city and the people who shape it. City data helps people find walks that work for them, and their experiences create better information for planning a city that works better on foot.