But adding in multiple data points and constraints, such as the fastest route with the cleanest air, is much trickier – and no urban walker wants to travel ten kilometres out of their way for a breath of fresh air. That’s quite simple for one data set on one network with a single constraint, such as finding the fastest route for a driver in traffic. “And secondly, you’ve got to use an algorithm that uses that data to find those routes.” Essentially, the air pollution modelling – or some other data set – needs to be combined with a path or road network. “First of all, you’ve got to deal with the data,” he says. In particular, he’s looking at building a tool to build circular routes for workouts.

Patrick O’Hara is a research assistant at the University of Warwick and a visiting research at Turing, and one of several researchers working at modelling air pollution and applying it to walking, running and cycling routes. There, researchers are gathering air quality data and building predictive models, in order to be able to tell Londoners what pollution is likely to be at a given time and place. Researchers at London’s Turing Institute are working on both sides of the walking route challenge – the data gathering and the algorithms – as part of their work on air pollution. “It’s important that travel apps improve – and not just for pedestrians that require mobility support.” “Active travel options, which cannot currently earn revenue for the app providers, can often be de-prioritised in app user interfaces in favour of linking through to private hire companies,” Braun says. But there’s more work to be done, in particular about accessibility, so those who can’t easily manage stairs aren’t given a route full of them, but also to show walking is just as easy as catching a cab or e-bike. As part of efforts to encourage more walking, Transport for London has backed Go Jauntly, an app that plans to add accessible routes between stations. Alongside public transport and paid-for micromobility options, Citymapper can now tell you which train stations are accessible to those with reduced mobility, while Google Maps highlights bike routes along less congested roads. There are plenty of countryside walking apps and some designed for tourists, and mapping and journey planners are getting better.

Citymapper play store