In most cities, traffic is something to look away from. In Dhaka it is the exhibition. Every cycle rickshaw carries a painted world on its hood, seat-back and mudguards: film stars mid-song, peacocks in impossible gardens, waterfalls that exist nowhere in the delta, the domes of dream mosques. Multiplied by several hundred thousand rickshaws, it amounts to a folk art movement with no gallery, no critics and an audience of millions stuck in traffic.

An art of the workshop yard

Rickshaw painting is produced in workshops where owners bring new vehicles for decoration the way others bring cars for a respray. A master painter and his apprentices divide the panels: one hand for faces, another for flowers, the lettering of blessings and film titles left to whoever has the steadiest wrist.

Speed is the aesthetic's engine. A rickshaw earns nothing in the workshop, so panels are painted fast, from memory, in enamel, with motifs the painters have executed ten thousand times and can vary the way musicians vary a standard tune.

What the pictures mean

The iconography is a census of popular desire. Film and television stars promise glamour; peacocks and roses, beauty; the great mosques and the Kaaba, piety; waterfalls and pine forests, a cool elsewhere that the delta's heat makes delicious. Birds crowd every empty corner, because the painters dislike emptiness and the customers love birds.

Owners choose motifs the way they choose everything about their vehicle: to be noticed, blessed and remembered in the traffic. A beautiful rickshaw rents for more and is forgiven more at junctions.

Art that works for a living

Unlike gallery art, rickshaw painting is maintained by use. Panels fade, crack and are repainted; styles migrate from city to village workshops; a popular film can repaint the fleet's hoods within a season. Scholars who once dismissed the work as kitsch now archive it as Bangladesh's most democratic art form.

The painters occupy the bottom of the art world's economy and the top of its output tables. A master may paint more faces in a year than a portraitist manages in a lifetime, for wages that make the comparison sting.

Pressure from print and policy

Printed vinyl, cheaper and faster than enamel, has eaten the simpler work, and periodic drives to reduce rickshaw numbers threaten the fleet itself. The workshops adapt: painters take house walls, shop shutters and wedding stages, carrying the style onto any flat surface the city offers.

Collectors and museums abroad have begun buying panels, which delights and baffles the painters in roughly equal measure. A hood painted for the street now hangs in Berlin. The street, meanwhile, orders another.

The moving exhibition

At evening the traffic thickens and the gallery glows: thousands of painted hoods under the streetlights, each with its star, its bird, its impossible waterfall, all of them inching home through the beautiful jam.

Dhaka may be the only city whose worst problem is upholstered in masterpieces. The painters, packing their brushes in the workshop yards, are in no doubt about the arrangement. The city gave them its traffic. They gave it back its pictures.