On a hot summer day, a treeless street might feel 15 or 20 degrees warmer than a dark street nearby. But most mapping tools – designed with drivers in mind – don’t give pedestrians any details on whether a particular road will be a comfortable walk. A new app from a public agency in Barcelona, called Walk cool, is different, letting users choose the shadiest route between two points.
When someone uses the app to find walking directions, there is an option to see the fastest route. But the app also shows a shady alternative, with a third option called “vampire mode” that allows pedestrians to completely avoid the sun. The app also shows where to drink fountains and shelters along the way.
The tool, which only works in one neighborhood for now, was difficult to build. “You need a lot of very detailed data,” says Albert Carbonell, lead analyst in the geographic information systems department of Barcelona Regional urban planning agency, who worked on the project with a team as part of a competition to use public data . Barcelona has already used LIDAR, a type of remote-sensing technology, to create a three-dimensional model of Barceloneta, a neighborhood on the city’s coast. The data were originally intended to map the risks of rising sea levels, but in the new tool, it helps map the shadow from trees and buildings, hour by hour, as the position of the sun changes. The city has already studied shade as part of a “tree master plan” to increase Barcelona’s canopy trees from 5% to 30%.
Because most maps look at the streets from the drivers ’perspective, the developers had to look in more detail at where the sidewalks were. “Since the shade is very different from one sidewalk to another, we needed to look at each sidewalk individually,” says Carbonell. In some cases, paths and public squares offered shortcuts that did not appear on standard maps, and the developers had to manually add them in.
It’s something that might be hard to replicate elsewhere, though as cities make plans reduce extreme heat, more data may become available on the exact location of shadows and sidewalks. Eventually, in an ideal scenario, each street will have enough shade that any road can work. But in the meantime, apps like this might help. Extreme heat is a growing problem almost everywhere, even in cities like Seattle which has historically been pretty cool.
Other institutions are rethinking how to improve pedestrian maps in different ways. The Turing Institute in London has studied local air pollution and created air quality forecasts that could be incorporated into a recommended market route (over the last year, they pivoted to study social distance between pedestrians). Another researcher at the Turing Institute has already considered the possibility of mapping the most beautiful walking routes, using a capable algorithm automatically rate the beauty in a location provided on Google Street View. It’s not clear how many tools like these could be used — someone in a hurry might not want to go out of their way just because a street has clean air or more trees. But it’s one more factor that might make it a little more likely that someone chooses to walk rather than drive.