In a previous post on Big Think, An Phung explored the rise of 'megacities,' the economic powerhouses that generate about 60 percent of the world’s GDP. 

Today we are looking at the reasons why the unprecedented scale of growth in urbanization, particularly in the developing world, necessitates smart planning. The urban population in Africa and Asia, for instance, is expected to double by 2030. 

We have known about this trend for some time. A United Nation Population Fund report in 2007 argued for "a revolution in thinking" about this demographic shift that has upset a balance between rural and urban populations "that has lasted for millennia." This represents both a crisis and an opportunity. For instance, will we see an unprecedented rise in urban poverty? Will we strain the planet's resources past the breaking point? On the other hand, urban centers offer populations better access to infrastructure, information and opportunity in today's knowledge economy. 

So the question remains: will we burry our heads in the sand or plan wisely for the future? What is the best way to accomodate the 5 billion people who will be living in cities in 18 years? Today we are focusing on urban transportation solutions. Big Think is presenting perspectives from leading scientists, economists and urban theorists who dare to dream big about the future of the city. 

1. 1 Bill Nye: Scientist on Wheels
2. 2 The True Cost of Congestion
3. 3 Faster, More Urban, More Diverse
4. 4 Dude, Where’s My Bike?