Some Observations About Stanford Campus Traffic

Traffic delays are an injury that the public inflicts upon itself. The instrument is the herd of bureaucrats who, being motivated only to retain their jobs with a minimum of hassle, cannot think carefully or creatively about what they control. Among the many foolish strategies that plague the driver, the top of my list has:

  1. Traffic lights that are controlled by bumpers, rather than being staggered to allow unimpeded flow along the main road.

  2. NIMBY-ism: town councils that respond positively to every neighborhood's desire to increase their comfort and property values by impeding traffic, thereby lowering every other person's comfort and the value of their homes. If you think about it, this game isn't even 0-sum, it's negative-sum, so on average our lives become harsher, even if there are a few winners.

  3. Four-way stop signs, perhaps the most irrational concept of all, and the topic of this essay.

How We Got 4-way Stop Signs on Campus

Once upon a time, Stanford was a cozier place. Rents in the local area were affordable by students and staff, and a large fraction of students were housed on campus. Bikes were the preferred mode of transportation, even for those living off-campus, because no one had to travel too far. There was a certain wisdom in encouraging bicycle use and even walking: they're good exercise, they're good for the environment, and they reduce the level of traffic. Then, it probably made sense to discourage the use of cars on campus, and the 4-way stop sign is one of the best ways, since it delays cars and thereby changes the equation in favor of biking or walking (well I suppose technically bikes are supposed to stop at these stop-signs too, but that doesn't seem to happen).

However, we live in different times. Rents are so high that for students and staff not given on-campus housing, the only options are often to live so far away that they have to drive to campus each day. Stanford victimizes these people in several ways. They are forced either to pay an incredible fee to park near their offices, or to pay with a wasted half-hour per day to park so far away that they have to take a shuttle to their office. These costs are not figured in, BTW, when Stanford compares its salaries with those at local industry, where parking is generally free and convenient. And of course the existence of myriad 4-way stop signs assures that those driving to campus will suffer additionally, even though they have no choice but to drive.

The True Cost of the 4-way Stop Sign

It bugs me to waste my time stopping unnecessarily. For me, that factor alone would be enough that I'd rip them out if I could. But for the more rational and temperate of you, here are some other factors that you should consider.

  1. Unnecessary stops waste gas.

  2. Unnecessary stops add to pollution.

  3. 4-way stop signs create confusion and increase the risk of accidents.

To begin, let's do a back-of-the-envelope calculation to see how much gas is wasted at 4-way stop signs on the Stanford campus. Here are my best guesses at the parameters of the problem; feel free to inform me if you have better estimates.

With these numbers, we can estimate the amount of gas wasted at 4-way stop signs each day. There are 40,000 trips per day, each with 10 unnecessary stops, for a total of 400,000 unnecessary stops per day. These stops use 800,000 ounces, or about 6000 gallons of gas per day. What does that number mean in practical terms?

  1. At $1.30/gallon, that's almost $3,000,000 paid for wasted gasoline per year.

  2. Assuming 35 gallons of gasoline obtained from a 42-gallon barrel of oil, that's 60,000 barrels per year we wouldn't have to import from some country that really doesn't have our best interests at heart.

  3. Since the vast majority of the pollution due to burning hydrocarbons occurs when accelerating the engine, we are probably creating pollution on campus something like burning that 6,000 gallons/day in an open field.

  4. And if the vague risk to our health due to increased polition were not enough, we can argue that unnecessary stops actually cost lives directly. Suppose each unnecessary stop wastes 15 seconds of your life. 400,000 such stops consume 6 million seconds per day. If you are lucky, you will live 3 billion seconds. That means campus stop signs waste a lifetime every year and a half.

Added Aug. 1, 2003: I found the following Analysis From the City of Winnipeg. It looks at first like it is advocating 4-way stop signs, but if you read to the end, you see that they outline the same sort of arguments against that I presented here. They also assert that a stop sign increases the yearly operating cost of a vehicle that crosses that intersection daily (presumably 730 stops/year) is $50. Even assuming that is Canadian dollars, their number is about 5 cents (US) per stop, considerably above my estimate. They may be including more than gas, e.g., wear-and-tear on the brakes, which must be replaced eventually.

The Dangers of 4-way Stop Signs

Nothing will protect us against the driver who doesn't care or doesn't notice a stop sign; they're going to cause an accident no matter what approach to traffic control we take. However, we can at least make sure that rational drivers are not induced to make an error.

At a 2-way stop sign, the rule is simple. If the sign is against you, you are burdened to make sure nothing bad happens. You may proceed only if you are certain there are no cars in the other direction that could hit you. It's hard to make a mistake if you are paying attention.

At a 4-way stop sign, it's not so simple. The rule is that the car arriving first can proceed first. If two cars arrive at the same time, you must yield on your right. But what does it mean to "arrive at the same time"? What if one driver, on the left, thinks they arrived 0.01 second before the driver on the right, while the one on the right calls the arrival "simultaneous." Each thinks they have the right of way. To make things worse, what does "arrive" actually mean? Can you "arrive" before you actually stop? Is crossing or touching the stop line equivalent to "arriving"? All this confusion draws the drivers' attention away from other matters, such as a bike or pedestrian trying to cross at the same time. The bottom line is that 4-way stop signs are an invitation to commit driving errors. Let's get rid of them.

Fixing the Problem

Here is a "modest" proposal for making things better.