Mike Wooldridge and Tanzanian development worker Mary Ndaro report on the opportunities and challenges for Dar es Salaam, Tanzania's commercial centre, and one of Africa’s fastest growing cities. Some six million people currently call Dar es Salaam home, but the city’s population has grown by a whopping 40% in just a decade. By the 2030s it is projected to become a megacity with a population of more than 10 million. Getting around cities like Dar es Salaam can be not only stressful but expensive, negotiating roads clogged with cars and choked with fumes, but the city is now investing in transport infrastructure to keep people moving.