Interesting, but cartographically, not a new idea. It’s a basic analytical (GIS) technique represented as a final map. You’re missing one of many of the aims of these on-street maps, with their indicative walk circles. We know they are not exact, but people like to meander and explore, not just move from A to B. Whether a walk is five minutes, or eight minutes, often doesn’t matter in reality.
The richness of such mapping helps them explore and build their own cognitive map of the area. They may want to take a route through a park rather than down some busy road. The user is quite capable of making their own decisions if presented with a good static map. Remember, not everyone lives with a smartphone (yet). Moreover, it often apparent on these maps, if done well, the clustering of services and activities as it is already part of the character of the city reimagined through the map.
Your approach looks good for an app, perhaps, but be minded about the move from tube (underground) use to walking in London (UK) as a result of this type of (static) mapping arriving on street. Before, London was a tube map, and a pure abstraction to visitors and locals alike, where people only knew areas around the tube stations. Nobody knew some of these journeys could be done in a few minutes on foot. Now, Londoners see the city differently, more richly—they explore more, use more facilities and services.
This article misses so many agendas within wayfinding and cartography. There is too much focus on ‘just get me from A to B’. As interesting as such tools are, we need to slow down on trying to constantly direct and curate people’s lives before we lose the ability to think and make decisions for ourselves. What happened to chance and serendipity in life?
I think Mapbox is a fantastic tool, but the application of the technology technology so often ignores so much of the whole body of knowledge and history in mapping, so applications can often be ill-judged. Cartogram, a useful Mapbox tool—except that isn’t a cartogram in the real sense of the word. A professional tool that ignores professional theory? Until developers and designers get a proper grounding in cartographic theory and history, they are, at best, only re-inventing what has already been done before in a digital form.
That said… keep it up. Anything pushing mapping forward is a good thing!