I am in a tiny steel cage attached to a motorcycle, stuttering through traffic in Dhaka, Bangladesh. In the last ten minutes, we have moved forward maybe three feet, inch by inch, the driver wrenching the wheel left and right, wriggling deeper into the wedge between a delivery truck and a rickshaw in front of us.

Up ahead, the traffic is jammed so close together that pedestrians are climbing over pickup trucks and through empty rickshaws to cross the street. Two rows to my left is an ambulance, blue light spinning uselessly. The driver is in the road, smoking a cigarette, standing on his tiptoes, looking ahead for where the traffic clears. Every once in awhile he reaches into the open door to honk his horn.

This is what the streets here look like from seven o’clock in the morning until ten o’clock at night. If you’re rich, you experience it from the back seat of a car, the percussion muffled behind glass. If you’re poor, you’re in a rickshaw, breathing in the exhaust.

Me, I’m sitting in the back of a CNG, a three-wheeled motorcycle shaped like a slice of pie and covered with scrap metal. I’m here working on a human rights project related (inevitably) to the garment factories, but whenever I ask people in Dhaka what their main priority is, what they think international organizations should really be working on, they tell me about the traffic.

It might not be as sexy as building schools or curing malaria, but alleviating traffic congestion is one of the defining development challenges of our time. Half the world’s population already lives in cities, and the United Nations estimates that proportion will rise to nearly 70 percent by 2050.