Biscayne Boulevard in downtown Miami, the city’s foyer, functions today as little more than a funnel for cars and trucks: eight or nine lanes of careening traffic and six blocks of median parking leave scant room for people, at a time when thousands of new residents are moving into the neighborhood’s growing concrete jungle.

What if the proportions were reversed? Would it be better instead to turn over much of that valuable public space to people, to pedestrians and cyclists and basketball players, to diners and playing children and music-lovers?

That’s just what the Downtown Development Authority has proposed, and Miamians will get a taste of how it all might work starting Friday. For three weeks, three blocks of parking under the Metromover guideway straddling Flagler Street will be temporarily occupied by pop-up public plazas enlivened by a program of concerts, movie screenings, dance and yoga lessons, and food and beer tastings.