For advocates of walkable, unpolluted and vehicle-free cities, the past few weeks have offered an unprecedented opportunity to test the ideas they have long lobbied for.

With Covid-19 lockdowns vastly reducing the use of roads and public transit systems, city authorities — from Liverpool to Lima — are taking advantage by closing streets to cars, opening others to bicycles and widening sidewalks to help residents maintain the six-foot distancing recommended by global health authorities.

Like jellyfish returning to Venice’s canals or flamingos flocking to Mumbai, pedestrians and cyclists are venturing out to places they previously hadn’t dared.

In Oakland, California, almost 10% of roadways have been closed to through-traffic, while Bogota, Colombia, has opened 47 miles of temporary bike lanes. New York has begun trialing seven miles of “open streets” to ease crowding in parks, with Auckland, Mexico City and Quito among the dozens of other cities experimenting with similar measures.

There are many purported benefits of “reclaiming” the streets during a pandemic.