Metros in the World: Providing Clean Mass Transit, Reducing Congestion and Car Emissions in Cities

Metros in the World: Providing clean mass transit, reducing congestion and car emissions, and improving safety are important considerations for implementing sustainable transport policies in cities.

Dependence of our mobility and life style on fossil fuel consumption is definitely not sustainable. Fossil fuel sources are diminishing, greenhouse gas emissions are reaching to an extremely high level, and migration of people from rural areas to urban areas and mobility needs are all accelerating these adverse impacts on the environment. There is a strong need to implement sustainable transportation policies for reducing dependence on fossil fuel, resulting emissions, congestion, and crashes.

Building more roads for relieving congestion due to car traffic is not a sustainable solution. Many cities are still trying to relieve congestion and accommodate higher rates of car ownership by building wider roads with more interchanges. But as the former mayor of Bogota, Enrique Peñalosa, said, “Trying to solve traffic problems by building more roads is like putting out a fire with gasoline.”

Fossil fuel free electric-powered metro (including electric tramways/buses, subways, light rails, and railways) and biofuel transit busses are sustainable and efficient solutions for mobility needs in cities. These mass transit technologies replace hundreds of thousands of car trips reducing congestion, greenhouse gas emissions, and demand on transportation related fossil fuel consumption. As shown in these figures, many cities have implemented metro transport infrastructure and/or expanding their metro networks (data credit: Wikipedia).

São Paulo Metro, August 2011: (left) Metro Station, (center) Metro Wall Art, (right) Metro Central Control Center

World’s largest metro systems:

  • The Tokyo Subway is the most highly used rapid transit system in the world.
  • The Shanghai Metro is the fourth busiest system in the world and the busiest in China.
  • The Hong Kong MTR is the tenth busiest system in the world and fourth in China.
  • The Beijing Subway is the fifth busiest system in the world.
  • The Guangzhou Metro is the sixth busiest system in the world and third in China.
  • The Moscow Metro is the busiest system in Europe and is known for its deep, beautifully decorated stations.
  • The New York City Subway is the busiest in the Americas and has more stations than any other, with 468 (or 423 counting transfer stations once) stations.
  • The Mexico City Metro is the busiest metro system in Latin America and the second busiest in the Americas
  • The London Underground, popularly known as the “Tube,” is the oldest system in the world, operating since 1863.

Sustainable Transportation: New York and Tokyo subways (video credit:

Videotect 2: Sustainable Transportation from Architecture Minnesota on Vimeo

Tokyo transportation system prioritizes pedestrian traffic by providing large crosswalks/bridges. (video credit: AIA, Minnesota)

Videotect 2: Tokyo Transportation from Architecture Minnesota on Vimeo

Dr. Uddin’s note:  I had the privilege of riding in rail track based metro in the following  cities worldwide including:  U.S. (New York, Washington DC, Atlanta, Chicago, San Francisco), Canada (Toronto), Mexico City, France (Paris), U.K. (London), Portugal (Lisbon), Italy (Rome), Turkey (Istanbul), Brazil (São Paulo, Rio de Janeiro), Hong Kong, China (Beijing, Shanghai’s Maglev train), Singapore, Malaysia (Kuala Lumpur), and Thailand (Bangkok). Additionally, I have traveled on commuter trains in Japan (Kyoto), Denmark (Copenhagen), Norway, China (Shanghai), Pakistan, and India. I can attest that most of the time I found these trips pleasant, safe, and stress free, except some time crowded condition.

I discuss in detail the impact of area and transportation sources on greenhouse gas and other air pollution in prior posts. More info is reviewed in Uddin’s Chapter 23 of Climate Change Mitigation Handbook, Springer, 2012.  


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