Getty Images / Gavin Hellier Urban mobility is fast becoming a major challenge for many large cities. Traffic jams, air pollution, and faulty infrastructures can make navigating cities a real struggle. By 2050, around 68% of the world's population will live in urban areas, placing even more strain on cities' transport systems. Consulting firm Oliver Wyman has ranked the top 15 cities based on the overall quality of their public transport systems. Visit Business Insider's homepage for more stories. Urban mobility is fast becoming a major challenge for many large cities.