Montreal's Musical Swings Only Work When Strangers Cooperate

Picture this: you're walking through downtown Montreal when you spot a row of glowing swings. You sit down, push off, and suddenly—music. Each swing triggers a different note, and as you pump your legs higher, the melody shifts. But something's missing. The tune sounds incomplete, almost lonely.

Then a stranger sits on the swing next to you. They start swinging too. And suddenly, the notes blend into something beautiful.

An Instrument for Strangers

This is 21 Balançoires (21 Swings), an interactive art installation that transforms a Montreal plaza into a giant musical instrument every spring. Created by design firm Daily tous les jours, the installation first appeared in 2011 and has become a beloved annual tradition in the Quartier des Spectacles.

The genius is in the design constraint: the music only works through cooperation. Each swing controls one musical element, but a single person can only create fragments. The full composition emerges only when multiple people swing in rhythm together—strangers forced into accidental collaboration.

How It Actually Works

• 21 swings arranged in a row, each lit with LED lights
• Motion sensors detect swinging patterns and speed
• Each swing triggers different sounds—some melodic, some percussive
• The algorithm blends sounds based on multiple swingers' movements
• Peak harmony only achievable with coordinated group effort

The technical side involves accelerometers in each swing feeding data to a central computer, which processes the movements in real-time to generate layered soundscapes. But you don't need to understand the engineering to feel the magic.

Designing for Connection

The creators had a specific goal: combat urban isolation. In a city where people rush past each other daily, 21 Balançoires forces interaction. You can't experience the full piece alone. You need the person next to you.

What happens is remarkable. Strangers start timing their swings. They laugh when the harmony clicks. Conversations spark between people who would never have spoken otherwise. Kids swing alongside grandparents. Tourists meet locals.

The installation has won multiple design awards and been replicated in cities worldwide, from London to Dubai. But Montreal remains home base, where the swings return each spring as a signal that winter is finally, mercifully, over.

Not Just a Bus Stop

While the installation is sometimes located near transit areas in the Quartier des Spectacles, it's not technically a bus stop—it's a dedicated public art space. But that detail matters less than the experience itself: mundane urban infrastructure transformed into something playful, collaborative, and genuinely joyful.

In an age of headphones and phone screens, 21 Balançoires does something radical. It makes strangers need each other, even if just for a song.