Children’s Streets” consist in pedestrianizing the streets around nursery and elementary school. The aim is to make the route between home and school safer for children, but also to combat pollution.
Removable barriers are installed wherever possible. They allow the passage of emergency vehicles and services (garbage trucks, etc.), but prohibit the passage of other motorized vehicles.
More picture and before/after sliders at the bottom: https://www.paris.fr/pages/57-nouvelles-rues-aux-ecoles-dans-paris-8197#des-rues-aux-enfants-avec-un-amenagement-specifique
Take heart, 20th-century car culture has no future. There’s no going back when people see the alternative. The USA is behind the curve but it will happen there too eventually.