Why building more roads doesn’t stop rush hour

JDN 2457362

The topic of this post was selected based on the very first Patreon vote (which was albeit limited because I only had three patrons eligible to vote and only one of them actually did vote; but these things always start small, right?). It is what you (well, one of you) wanted to see. In future months there will be more such posts, and hopefully more people will vote.

Most Americans face an economic paradox every morning and every evening. Our road network is by far the largest in the world (for three reasons: We’re a huge country geographically, we have more money than anyone else, and we love our cars), and we continue to expand it; yet every morning around 8:00-9:00 and every evening around 17:00-18:00 we face rush hour, in which our roads become completely clogged by commuters and it takes two or three times as long to get anywhere.

Indeed, rush hour is experienced around the world, though it often takes the slightly different form of clogged public transit instead of clogged roads. In most countries, there are two specific one-hour periods in the morning and the evening in which all transportation is clogged to a standstill.

This is probably such a familiar part of your existence you never stopped to question it. But in fact it is quite bizarre; the natural processes of economic supply and demand should have solved this problem decades ago, so why haven’t they?

There are a number of important forces at work here, all of which conspire to doom our transit systems.

The first is the Tragedy of the Commons, which I’ll likely write about in the future (but since it didn’t win the vote, not just yet). The basic idea of the Tragedy of the Commons is similar to the Prisoner’s Dilemma, but expanded to a large number of people. A Tragedy of the Commons is a situation in which there are many people, each of whom has the opportunity to either cooperate with the group and help everyone a small amount, or defect from the group and help themselves a larger amount. If everyone cooperates, everyone is better off; but holding everyone else’s actions fixed, it is in each person’s self-interest to defect.

As it turns out, people do act closer to the neoclassical prediction in the Tragedy of the Commons—which is something I’d definitely like to get into at some point. Two different psychological mechanisms counter one another, and result in something fairly close to the prediction of neoclassical rational self-interest, at least when the number of people involved is very large. It’s actually a good example of how real human beings can deviate from neoclassical rationality both in a good way (we are altruistic) and in a bad way (we are irrational).

The large-scale way roads are a Tragedy of the Commons is that they are a public good, something that we share as a society. Except for toll roads (which I’ll get to in a moment), roads are set up so that once they are built, anyone can use them; so the best option for any individual person is to get everyone else to pay to build them and then quite literally free-ride on the roads everyone else built. But if everyone tries to do that, nobody is going to pay for the roads at all.

And indeed, our roads are massively underfunded. Simply to maintain currently-existing roads we need to spend about an additional $100 billion per year over what we’re already spending. Yet once you factor in all the extra costs of damaged vehicles, increased accidents, time wasted, and the fact that fixing things is cheaper than replacing them, in fact the cost to not maintain our roads is about 3 times as large as that. This is exactly what you expect to see in a Tragedy of the Commons; there’s a huge benefit for everyone just sitting there, not getting done, because nobody wants to pay for it themselves. Michigan saw this quite dramatically when we voted down increased road funding because it would have slightly increased sales taxes. (Granted, we should be funding roads with fuel taxes, not general sales taxes—but those are hardly any more popular.)

Toll roads can help with this, because they internalize the externality: When you have to pay for the roads that you use, you either use them less (creating less wear and tear) or pay more; either way, the gap between what is paid and what is needed is closed. And indeed, toll roads are better maintained than other roads. There are downsides, however; the additional effort to administrate the tolls is expensive, and traffic can be slowed down by toll booths (though modern transponder systems mitigate this effect substantially). Also, it’s difficult to fully privatize roads, because there is a large up-front cost and it takes a long time for a toll road to become profitable; most corporations don’t want to wait that long.

But we do build a lot of roads, and yet still we have rush hour. So that isn’t the full explanation.

The small-scale way that roads are a Tragedy of the Commons is that when you decide to drive during rush hour, you are in a sense defecting in a Tragedy of the Commons. You will get to your destination sooner than if you had waited until traffic clears; but by adding one more car to the congestion you have slowed everyone else down just a little bit. When we sum up all these little delays, we get the total gridlock that is rush hour. If you had instead waited to drive on clear roads, you would get to your destination without inconveniencing anyone else—but you’d get there a lot later.

The second major reason why we have rush hour is what is called induced demand. When you widen a road or add a parallel route, you generally fail to reduce traffic congestion on that route in the long run. What happens instead is that driving during rush hour becomes more convenient for a little while, which makes more people start driving during rush hour—they buy a car when they used to take the bus, or they don’t leave as early to go to work. Eventually enough people shift over that the equilibrium is restored—and the equilibrium is gridlock.

But if you think carefully, that can’t be the whole explanation. There are only so many people who could start driving during rush hour, so what if we simply built enough roads to accommodate them all? And if our public transit systems were better, people would feel no need to switch to driving, even if driving had in fact been made more convenient. And indeed, transportation economists have found that adding more capacity does reduce congestion—it just isn’t enough unless you also improve public transit. So why aren’t we improving public transit? See above, Tragedy of the Commons.

Yet we still don’t have a complete explanation, because of something that’s quite obvious in hindsight: Why do we all work 9:00 to 17:00!? There’s no reason for that. There’s nothing inherent about the angle of sunlight or something which requires us to work these hours—indeed, if there were, Daylight Savings Time wouldn’t work (which is not to say that it works well—Daylight Savings Times kills).

There should be a competitive market pressure to work different hours, which should ultimately lead to an equilibrium where traffic is roughly constant throughout the day, at least during the time when a large swath of the population is awake and outside. Congestion should spread itself out over time, because it is to the advantage of all involved if each driver tries to drive at a time when other driver’s aren’t. Driving outside of rush hour gives us an opportunity for something like “temporal arbitrage”, where you can pay a small amount of time here to get a larger amount of time there. And if there’s one thing a competitive economy is supposed to get rid of, it’s arbitrage.

But no, we keep almost all our working hours aligned at 09:00-17:00, and thus we get rush hour.

In fact, a lot of jobs would function better if they weren’t aligned in this way—retail sales, for example, is most successful during the “off hours”, because people only shop when they aren’t working. (Well, except for online shopping, and even then they’re not supposed to.) Banks continually insist on making their hours 9:00 to 17:00 when they know that on most days they’d actually get more business from 17:00 to 19:00 than they did from 9:00 to 17:00. Some banks are at least figuring that out enough to be open from 17:00 to 19:00—but they still don’t seem to grasp that retail banking services have no reason to be open during normal business hours. Commerce banking services do; but that’s a small portion of their overall customers (albeit not of their overall revenue). There’s no reason to have so many full branches open so many hours with most of the tellers doing nothing most of the time.

Education would be better off being later in the day, when students—particularly teenagers—have a chance to sleep in the way their brains are evolved to. The benefits of later school days in terms of academic performance and public health are actually astonishingly large. When you move the start of high school from 07:00 to 09:00, auto collisions involving teenagers drop 70%. Perhaps should be the new slogans: “Early classes cause car crashes.” Since 25% of auto collisions occur during rush hour, here’s another: “Always working nine to five? Vehicular homicide.”

Other jobs could have whatever hours they please. There’s no reason for most forms of manufacturing to be done at any particular hour of the day. Most clerical and office work could be done at any time (and thanks to the Internet, any place; though there are real benefits to working in an office). Writing can be done whenever it is convenient for the author—and when you think about it, an awful lot of jobs basically amount to writing.

Finance is only handled 09:00-17:00 because we force it to be. The idea of “opening” and “closing” the stock market each day is profoundly anachronistic, and actually amounts to granting special arbitrage privileges to the small number of financial institutions that are allowed to do so-called “after hours” trading.

And then there’s the fact that different people have different circadian rhythms, require different amounts of sleep and prefer to sleep at different times—it’s genetic. (My boyfriend and I are roughly three hours phase-shifted relative to one another, which made it surprisingly convenient to stay in touch when I lived in California and he lived in Michigan.)

Why do we continue to accept such absurdity?

Whenever you find yourself asking that question, try this answer first, for it is by far the most likely:

Social norms.

Social norms will make human beings do just about anything, from eating cockroaches to murdering elephants, from kilts to burqas, from waving giant foam hands to throwing octopus onto ice rinks, from landing on the moon to crashing into the World Trade Center, from bombing Afghanistan to marching on Washington, from eating only raw foods to using dead pigs as sex toys. Our basic mental architecture is structured around tribal identity, and to preserve that identity we will follow almost any rule imaginable. To a first approximation, all human behavior is social norms.

And indeed I can find no other explanation for why we continue to work on a “nine-to-five” 09:00-17:00 schedule (or for that matter why it probably feels weird to you that I say “17:00” instead of the far less efficient and more confusion-prone “5:00 PM”). Our productivity has skyrocketed, increasing by a factor of 4 just since 1950 (and these figures dramatically underestimate the gains in productivity from computer technology, because so much is in the form of free content, which isn’t counted in GDP). We could do the same work in a quarter the time, or twice as much in half the time. Yet still we continue to work the same old 40-hour work week, nine-to-five work day. We each do the work of a dozen previous workers, yet we still find a way to fill the same old work week, and the rich who grow ever richer still pay us more or less the same real wages. It’s all basically social norms at this point; this is how things have always been done, and we can’t imagine any other way. When you get right down to it, capitalism is fundamentally a system of social norms—a very successful one, but far from the only possibility and perhaps not the best.

Thus, why does building more roads not solve the problem of rush hour? Because we have a social norm that says we are all supposed to start work at 09:00 and end work at 17:00.
And that, dear readers, is what we must endeavor to change. Change our thinking, and we will change the norms. Change the norms, and we will change the world.


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