Enrique Peñalosa, mayor of Bogotá, Colombia, once said the following:

“A developed country is not a place where the poor have cars, but where the rich use public transportation.”

That simple, yet compelling statement resonated strongly with me since my idea of public transportation has varied with every city I’ve lived in. In my native Mexico City, public transportation is regarded as a cumbersome and dangerous alternative to those who cannot afford a car. In Tel Aviv, the cost of owning a car is so high that people of all socioeconomic backgrounds have to put up with the often chaotic and unreliable bus system to get around. On the other hand, in San Diego the distances are so large and public transportation is so partial that it is virtually impossible to depend on it.

One morning, as I was waiting in the crowded Berkeley BART Station on my way to San Francisco, I began to think about what makes public transportation efficient. Of course, an efficient system has to be:

comprehensive enough to take you between two arbitrary points within a city,

enough to take you between two arbitrary points within a city, reliable enough that you can trust it to take you to your destination reasonably on time,

enough that you can trust it to take you to your destination reasonably on time, fast enough to warrant not spending more money in order to use a car instead.

Using this somewhat naive definition of efficient, I set out to briefly determine which public transportation systems around the world are the most efficient.

In order to find a quantifiable measure of efficient, I looked back to Peñalosa’s words. As such, the most important metric that makes a public transportation system efficient is how much better of an alternative it is to driving. Commuters who cannot afford a car are forced to take public transit regardless of how slow, unreliable, or inaccessible it is. However, in order to convince wealthier people to also commute by transit, the system must be as fast to driving as possible. Of course, if a system existed which was always a faster alternative to driving, no one would need a car!

Here are two examples illustrating this point. Both of the following were taken directly from the dataset.