Cities everywhere suffer from traffic congestion. One way to combat this problem has been to find ways to increase the number of people in each vehicle. According to the U.S. Department of Energy the average number of people in a car is 1.59. Actually it’s worse than that because many of the people you see in cars are not trying to go anywhere themselves, they’re just drivers. They may be chauffeuring the kids to the soccer game, or taking grandma to the doctor, or picking up the spouse at the airport. Designers of Automated Transit Networks (ATNs) expect to see more actual travelers per vehicle than is typical of cars. Why? The easiest way to explain that is with an example.
Let’s say that Mary and John are co-workers, and they have decided to go out to dinner together after work. Will they share a ride? If they each drove to work in their own car, and shared a ride to the restaurant, then after dinner they would have to drive back to work to retrieve the other car. It’s just easier for Mary and John to each drive their own car to the restaurant. So even though they are starting from the same place, and going to the same place, at the same time, for the purpose of being together, they still won’t share a ride. But if they’ve come to work on an ATN, it’s only natural for them to share a ride to the restaurant.
The point of this is that, generally speaking, people will only choose to share a car if they plan to start and end at the same place, and visit all the same places at the same times. Or to put it it another way, if you want to have the use of your car at any point during the day, you have to keep it nearby all the time. By contrast, with an ATN, since you can catch a pod anywhere and leave it anywhere, people will spontaneously share a ride whenever their travels coincide, without the need for any coercion or incentives. With small four-seater pods, this level of ride sharing should be sufficient to make good use of the available capacity. And the example above is not an unusual one. There are countless other scenarios that illustrate this same phenomenon. What if you are going to an event together, but one of you might need to leave early? Or you’re on a first date, and you want the opportunity to escape if it doesn’t go well? Or you and your spouse are meeting somewhere, and going home together?
There are certain unusual situations where it may be practical and worthwhile to facilitate ride sharing. For example at a convention center where a great many people leave at the same time, and most will be traveling to one of a small number of locations – the convention hotels. This can be easily accomplished with a multi-berth station in which each berth is dedicated to a single destination. People could queue up at the appropriate berth and the line will move as quickly as pods can pull in, load, and pull out. Experience with existing ATN systems has shown that in these circumstances nearly every seat will be filled. This could provide better service at lower cost that the usual fleet of hotel busses. But beyond these special cases, we believe that facilitated ride sharing, where strangers are grouped into vehicles by a computer, introduces complexity, delays, and security concerns that are not outweighed by the small increase in capacity they might provide.