The last mile problem is the critical utilization barrier for many transit networks. It occurs when the origin or destination of a trip is difficult to access by a short walk. This bottleneck can outweigh the benefits of even the fastest, most comfortable transit systems. Travelers who lack access to (or knowledge of) solid options for getting to and from transit hubs will not even consider public transit as a viable option–– and rightly so. The choice between a transit journey requiring a long walk that might double the length of the trip to simply get to the station versus a convenient, single-mode trip in your car is a foregone conclusion. The vast majority of Americans, even the transit lovers amongst us, will opt for the car ride.

We all make transportation decisions like these every day, so it is not surprising to learn that ridership is negatively correlated with walking distance to stations. As a general rule of thumb, people are willing to walk up to 400m (1/4 mile) to transit. Any further, and most people won't even consider that transit as a viable option. With this in mind, there are two ways to solve the last mile problem and in turn to increase ridership:

  1. Extend existing networks (subway lines, bus routes, etc.) to increase the number of homes and destinations within that 400m range.
  2. Widen the corridor within which people are willing to travel to transit.

The first option is feasible only in the most dense urban areas like Manhattan. In sprawling metropolitan areas (which describes the communities in which the vast majority of Americans live), neighborhoods are too sparse to justify the high cost and complexity of additional transit lines. For public transit to be a viable substitute to cars, we must focus on maximizing the width of the corridor it serves.

In other words, we need to focus our efforts on decreasing the downward slope that maps the relationship between ridership and distance to transit. This goal can only be achieved with a multi-pronged approach, with a diversity of solutions to fit a wide variety of needs. Traditional solutions have included buses, taxis, bicycles, and ridesharing. In the case of long rail trips, some people even solve that last-mile problem by driving to the train station. More recently, private companies like Uber, Lyft, and Zipcar have come into this space as well, enabling people to renounce car ownership despite living farther than 400m away from transit.

In parallel to the expanding array of last mile solutions, Americans have opted for an increasingly urban lifestyle, and young people in particular have welcomed a lifestyle that is less car-dependent than that of their parents. We must widen the transit corridors of existing networks with innovative last mile solutions in order to best capitalize on this cultural shift. The cultural and technical potential is there–– now, it's up to urban planners to jump on this opportunity to shift America away from its dependence on cars.

The Bay Area is a good case study of the challenges and some of the solutions I mentioned above. I'll expand upon how the region has tackled this problem (and how it could improve!) in another post soon.