An intersection with traffic in downtown Hanoi, Vietnam.

The streets of Hanoi are increasingly awash in motorbikes. The old streets of the city’s French and Ancient Quarters are perceived to be especially chaotic because the streets are narrower and rules are guided by informal norms.

“Foreigners see chaos when they look at these narrow streets filled with weaving motorbikes,” said in a recent interview. “When I first arrived, I had no idea how to get across a street.”

But those who live there do. Pedestrians do not look both ways before stepping into the street. They walk slowly and steadily while the ubiquitous motorbikes swarm around them, “like a river swirling past a stone.”

Visitors unaware of this system wait for a gap in traffic then dash across the street, which causes confusion among those on motorbikes who don’t know what to make of someone running erratically across the road.