Wednesday, November 3, 2010

The Economics of Frontal-Bus-Squishage

Have you ever gotten onto a city bus and immediately been stuck in a huge cluster of people at the front of the bus, when there is plenty of space, and maybe even seats in the back? I have often struggled with this curious phenomenon, and my inner economist seeks a reason for, and maybe a solution to this problem. I have come to the conclusion that the problem of front-of-bus squishage can be easily understood through an examination of the unique costs and benefits that riders face in different parts of the bus.

When people think of prices, they often think only of money given in exchange for something else of value. But everything of value has a price, often not paid in money, but with other assets, such as personal space, comfort or dignity. Personal space is the asset that bus riders often give up when they are crammed together in the front of the bus, even when there are unused assets towards the back that could make everyone’s ride more pleasant.
Why do these assets go unused? After careful consideration, I've realized that bus blockage situations happen because of two things:
1. The bus riders who would most benefit from the extra space on the bus are those who would face the most costs in acquiring it. And,
2. Bus riders who would face the least costs in acquiring more space on the bus are those who would least benefit from more space.
To put this more simply, those who can more easily access the extra space have less need for it. Thus the extra space in the back goes unused.
Allow me to explain.
Envision an empty bus. As riders get on the bus, they immediately take the seats. Once all of the seats are taken, riders have no choice but to stand. In the absence of external forces, people will tend to want to stay put. In more common usage this can be categorized as "laziness". Because of this law of behavioral inertia, riders who come onto a bus with no available seats, rather than moving immediately to the back to clear space for new riders, will tend to stand in the front, relatively close to where they got on. There is, when entering a non-crowded bus with no available seats, no direct and universal incentive for bus riders to move further back, and because of this, as more riders get on the bus, clusters of frontal-bus-squishage form. And because of the different costs and benefits facing bus riders at different parts of the bus, once they form, these clusters are hard to break up. To help explain, take a look at this diagram I have artfully put together:

The diagram singles out two bus riders, person A and person B. Person A is stuck in the middle of a cluster of people (zone A), while person B is at the edge of the cluster, (in the spacious zone B). In this formation, Person A would greatly benefit from the extra space at the back of the bus, but would face the costs of squishing past three people in order to get there.
If you think the word "cost" is inappropriate to describe what person A faces here, ask yourself: do you enjoy squishing past people in thick crowds? Probably not, both for your sake, and out of a polite desire not to squish others. Thus you would face a cost in getting from zone A to zone B. The unpleasant squishing would be the price you’d pay for more space.

So person A, in order to benefit himself, and indirectly the people around him (in econ-speak, a positive externality), would pay a relatively high price for moving to zone B. Person A would need to press up against other riders, and awkwardly slide and slither through. This is a cost, as real to person A as the cost of a loaf of bread. Person B however, who is already at the edge of zone B, has plenty of space in front of him. And for the relatively low cost of simply moving his feet for a few steps, Person B could move further into zone B, and thus help lighten the blockage for everyone in zone A. But because person B is not being squished from both sides like everyone in zone A, he won't personally benefit much from moving towards the back. Person B's needs for space have largely been satisfied.
In the act of moving towards the back, Person A and other riders like him, face high costs and high benefits, while Person B and other riders like him face low costs and low benefits.
And there we have it. A cluster of front-of-bus-squishage. The cluster will break only if:
1. person B and/or others like him realize that they need to move back, or
2. if a few brave (or rude?) souls in Zone A decide it is better to squish past everyone to get to zone B, than to remain in the cluster. This is an altogether less pleasant solution than in 1, which involves no extra squishage.

So far there is only one tool in use that I know of for preventing or resolving the frontal bus squishage problem: Shame. The bus driver needs to shame the "person B"s of the world into moving back, usually by yelling "move back, everybody". (Even more effective is "I'm not moving this bus until you move to the back!") But maybe an automated system would be more effective. If money were no object, engineers could design a bus that uses sensors to detect clusters of frontal bus squishage. Upon detection, a polite yet insistant robot voice could ask the "person B"s to "please move back" over and over until the situation was resolved. If need be, it could also give them mild electric shocks until they do. Here is a diagram of how that would work:

(I sure hope anyone reading this has a sense of irony. For the record, I am not a psycho.)

But what about carrots rather than sticks? Adding extra benefits in exchange for moving to the back could work just as well, or even better than shame or electrocution. How about a free snack dispenser, or a gentle foot-massaging floor that activates in the back when the sensors detect a squishage?
All kidding aside, to solve this problem, the costs and benefits must be realligned, either by making it more costly to create a blockage, or more beneficial to prevent one. In econ-speak this would "internalize the externality." Snacks, electric shocks, or massages could theoretically all be used. But in reality, it seems we can only rely upon the shame that a good and forceful bus-driver can inflict on Person B. That, and hopefully, bus riders' courtesy to their fellow passengers will help too.

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