  In the wake of the pandemic, the inadequacy of urban sidewalks to comply with
social distancing remains untackled in academy. Beyond isolated efforts (from
sidewalk widenings to car-free Open Streets), there is a need for a large-scale
and quantitative strategy for cities to handle the challenges that COVID-19
poses in the use of public space. The main obstacle is a generalized lack of
publicly available data on sidewalk infrastructure worldwide, and thus city
governments have not yet benefited from a complex systems approach of treating
urban sidewalks as networks. Here, we leverage sidewalk geometries from ten
cities in three continents, to first analyze sidewalk and roadbed geometries,
and find that cities most often present an arrogant distribution of public
space: imbalanced and unfair with respect to pedestrians. Then, we connect
these geometries to build a sidewalk network --adjacent, but not assimilable to
road networks, so fertile in urban science. In a no-intervention scenario, we
apply percolation theory to examine whether the sidewalk infrastructure in
cities can withstand the tight pandemic social distancing imposed on our
streets. The resulting collapse of sidewalk networks, often at widths below
three meters, calls for a cautious strategy, taking into account the
interdependencies between a city's sidewalk and road networks, as any
improvement for pedestrians comes at a cost for motor transport. With notable
success, we propose a shared-effort heuristic that delays the sidewalk
connectivity breakdown, while preserving the road network's functionality.
